EPA-600/R-09/130 

October 2009 

Characterization of Emissions 

from Commercial Aircraft 

Engines during the Aircraft 

Particle Emissions eXperiment 

(APEX) 1 to 3 

Characterization of Emissions from Commercial 
 

Aircraft Engines during the Aircraft Particle 
 

Emissions eXperiment (APEX) 1 to 3 
 

John S. Kinsey, QEP 
 

Principal Investigator
 


Office of Research and Development 
 

National Risk Management Research Laboratory 
 

Research Triangle Park, NC 27711
 


Office of Research and Development 
 

U.S. Environmental Protection Agency 
 

Washington DC 
 

October 2009 
 
EPA Review Notice 

This report has been peer and administratively reviewed by the U.S. Environmental Protection Agency 

and approved for publication. Mention of trade names or commercial products does not constitute 

endorsement or recommendation for use. 

This document is available to the public through the National Technical Information Service, Springfield, 

Virginia 22161. 
Foreword 

The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's 

land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to 

formulate and implement actions leading to a compatible balance between human activities and the ability 

of natural systems to support and nurture life. To meet this mandate, EPA's research program is providing 

data and technical support for solving environmental problems today and building a science knowledge 

base necessary to manage our ecological resources wisely, understand how pollutants affect our health, 

and prevent or reduce environmental risks in the future. 

The National Risk Management Research Laboratory (NRMRL) is the agency's center for investigation of 

technological and management approaches for preventing and reducing risks from pollution that threaten 

human health and the environment. The focus of the laboratory's research program is on methods and 

their cost-effectiveness for prevention and control of pollution to air, land, water, and subsurface 

resources; protection of water quality in public water systems; remediation of contaminated sites, 

sediments and ground water; prevention and control of indoor air pollution; and restoration of 

ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that 

reduce the cost of compliance and to anticipate emerging problems. NRMRL's research provides 

solutions to environmental problems by: developing and promoting technologies that protect and improve 

the environment; advancing scientific and engineering information to support regulatory and policy 

decisions; and providing the technical support and information transfer to ensure implementation of 

environmental regulations and strategies at the national, state, and community levels. 

This publication has been produced as part of the laboratory's strategic long-term research plan. It is 

published and made available by EPA's Office of Research and Development to assist the user 

community and to link researchers with their clients. 

Sally Gutierrez, Director 

National Risk Management Research Laboratory 
Acknowledgements 

Technical support for the preparation of this report was provided by ARCADIS-US, Inc., 4915 Prospectus 

Drive, Suite F, Durham, NC under EPA Contract No. EP-C-04-023, Work Assignments 3-14 and 4-14 and 

EPA Contract No. EP-C-09-027, Work Assignment 0-2. ARCADIS personnel participating in the research 

included Dr. Yuanji Dong, Mr. Craig Williams, Ms. Kim Egler, Mr. Rus Hames and Mr. Russell Logan. 
Table of Contents 

Table of Contents ........................................................................................................................................... i
 


List of Appendices ......................................................................................................................................... iv
 


List of Figures ................................................................................................................................................ v
 


List of Tables ................................................................................................................................................ xii
 


List of Acronyms, Initializations, and Abbreviations .................................................................................... xiv
 


Executive Summary .................................................................................................................................... xix
 


1. Introduction ......................................................................................................................................... 1
 


1.1 Background..................................................................................................................................... 1
 


1.2 Research Objectives ...................................................................................................................... 2
 


1.3 Organization of this Report............................................................................................................. 2
 


2. Test Site Description and Engine Specifications ............................................................................... 5
 


2.1 APEX-1 Site Description and Setup ............................................................................................... 5
 


2.2 APEX-2 Site Description and Setup ............................................................................................... 7
 


2.3 APEX-3 Site Description and Setup ............................................................................................... 9
 


2.4 Engines Tested ............................................................................................................................. 12
 


3. Experimental Apparatus ................................................................................................................... 15
 


3.1 General Description ...................................................................................................................... 15
 


3.2 Sampling System .......................................................................................................................... 16
 


3.3 Instrumentation ............................................................................................................................. 24
 


3.3.1 Tapered Element Oscillating Microbalance Monitors .............................................................. 24
 


3.3.2 Quartz Crystal Microbalance ................................................................................................... 24
 


3.3.3 Electrical Low Pressure Impactor ............................................................................................ 24
 


3.3.4 Engine Exhaust Particle Sizer ................................................................................................. 24
 


3.3.5 Scanning Mobility Particle Sizer .............................................................................................. 25
 


3.3.6 Condensation Particle Counter ............................................................................................... 25
 


3.3.7 Aethalometer........................................................................................................................... 25
 


3.3.8 Photoelectric Aerosol Sensor .................................................................................................. 26
 


3.3.9 Tracer Gas Analyzer ............................................................................................................... 26
 


3.3.10 Thermal Denuder .................................................................................................................... 26
 


3.3.11 Carbon Dioxide Analyzer ........................................................................................................ 27
 


3.4 Data Acquisition System ............................................................................................................... 27
 


4. Experimental Procedures ................................................................................................................. 29
 


4.1 General Sampling Approach ........................................................................................................ 29
 


4.2 Pre-test Procedures ...................................................................................................................... 29
 


4.2.1 System Cleaning and Leak Checks ........................................................................................ 29
 


4.2.2 Sampling Media Preparation ................................................................................................... 30
 


4.2.3 Particle Instrument Calibration ................................................................................................ 31
 


4.2.4 Gas Analyzer Calibration ........................................................................................................ 31
 


4.3 Field Sampling Procedures .......................................................................................................... 31
 


4.3.1 Continuous Analyzer Operation .............................................................................................. 31
 


4.3.2 Instrumental Quality Control Checks ...................................................................................... 31
 


4.3.3 Gas Analyzer QC Checks ....................................................................................................... 36
 


4.3.4 Time-Integrated Sampling ....................................................................................................... 36
 


i 
4.3.5 Documentation ........................................................................................................................ 37
 


4.4 Laboratory Analysis Procedures................................................................................................... 37
 


4.5 Sample Preservation and Storage................................................................................................ 38
 


4.6 Post-Test Laboratory Procedures ................................................................................................. 38
 


4.6.1 PM Gravimetric Analysis ......................................................................................................... 38
 


4.6.2 Elemental Analysis .................................................................................................................. 39
 


4.6.3 Analysis of Water-Soluble Inorganic Ions ............................................................................... 39
 


4.6.4 Analysis of Organic and Elemental Carbon ............................................................................ 40
 


4.6.5 Analysis of Particle Phase Organic Compounds .................................................................... 40
 


4.6.5.1	 Solvent Extraction Methodology...................................................................................... 42
 


Sample Extraction and Concentration .......................................................................................... 42
 


Extract Methylation ....................................................................................................................... 42
 


GC/MS Analysis ............................................................................................................................ 42
 


4.6.5.2	 Thermal Desorption Methodology................................................................................... 43
 


Sample Preparation ...................................................................................................................... 43
 


Thermal Desorption ...................................................................................................................... 43
 


GC/MS Analysis ............................................................................................................................ 43
 


4.6.5.3 Analysis of PUFs ............................................................................................................. 44
 


4.7 Analysis of Gas Phase Samples .................................................................................................. 44
 


4.7.1 Analysis of SUMMA Canister Samples ................................................................................... 44
 


4.7.2 Analysis of DNPH-Impregnated Silica Gel Cartridges ............................................................ 44
 


4.8 Determination of Particle Line Losses .......................................................................................... 44
 


4.8.1 Experimental Setup and Preparations .................................................................................... 45
 


4.8.2 Sampling Procedures .............................................................................................................. 46
 


5.	 Data Analysis ................................................................................................................................... 49
 


5.1 Data Reduction Procedures ......................................................................................................... 49
 


5.1.1 Total PM-2.5 Mass Concentration ........................................................................................... 49
 


5.1.2 Elemental Carbon/Organic Carbon ......................................................................................... 50
 


5.1.3 Semivolatile Organics ............................................................................................................. 51
 


5.2	 Calculation of Count and Mass Emission Indices for PM, Gas-Phase and Particle-Phase
 


Compounds .................................................................................................................................. 52
 


5.2.1 PM Calculations ...................................................................................................................... 52
 


5.2.2 Gas-Phase Calculations .......................................................................................................... 53
 


5.2.3 Particle-Phase Calculations .................................................................................................... 53
 


5.3 Determination of Particle Size Distribution ................................................................................... 53
 


5.4 Calculation of Data Quality Indicator Goals .................................................................................. 54
 


5.5 Particle Loss Correction ............................................................................................................... 55
 


6. Test Matrix, Fuel Composition, and Engine Operation .................................................................... 59
 


6.1 Test Matrix and Run Times .......................................................................................................... 59
 


6.2 Fuel Type and Composition .......................................................................................................... 59
 


6.3 Engine Power Settings ................................................................................................................. 62
 


6.3.1 APEX-1 Engine Test Cycles ................................................................................................... 62
 


6.3.2 APEX-2 Engine Test Cycles ................................................................................................... 63
 


6.3.3 APEX-3 Engine Test Cycles ................................................................................................... 67
 


7.	 Environmental and Engine Operating Data ..................................................................................... 73
 


7.1 Wind Speed and Direction ............................................................................................................ 73
 


ii 
7.2 Fuel Flow Rate.............................................................................................................................. 74
 


7.3 Carbon Dioxide Monitoring ........................................................................................................... 77
 


8. Particulate Matter Mass Emissions .................................................................................................. 85
 


8.1 Effect of Fuel Flow Rate and Engine Thrust................................................................................. 87
 


8.2 Effect of Fuel Composition ........................................................................................................... 95
 


8.3 Effect of Engine Type ................................................................................................................... 98
 


8.4 Effect of Cold and Warm Engine Conditions .............................................................................. 100
 


8.5 Comparison of Particle Mass Emission Indices Obtained from Different Instruments............... 100
 


8.6 Teflon Filter Integrated Sampling Results .................................................................................. 105
 


9. PM Number Emissions ................................................................................................................... 109
 


9.1 Effect of Fuel Flow Rate ............................................................................................................. 110
 


9.2 Effect of Fuel Composition ......................................................................................................... 117
 


9.3 Effect of Engine Type ................................................................................................................. 119
 


9.4 Effect of Cold and Warm Engine Conditions .............................................................................. 120
 


9.5 Comparison of Particle Number Emission Indices Obtained from Different Instruments ........... 124
 


10. Particle Size Distribution and Geometric Mean Diameter .............................................................. 127
 


10.1 Particle Size Results for APEX-1 ................................................................................................ 127
 


10.2 Particle Size Results for APEX-2 ................................................................................................ 128
 


10.3 Particle Size Results for APEX-3 ................................................................................................ 128
 


10.4 Effects of Particle Loss Correction on PSD Results ................................................................... 153
 


10.5 Effect of Engine Power and Fuel Flow Rate ............................................................................... 155
 


10.6 Effects of Fuel Type .................................................................................................................... 165
 


10.6 Effects of Engine Type ............................................................................................................... 165
 


10.7 Effects of Cold and Warm Engine Conditions ............................................................................ 172
 


10.8 Effect of Probe Position on PSD ................................................................................................. 172
 


10.9 Comparison of PSDs Measured by Different Instruments ......................................................... 179
 


11. Black Carbon and PAH Emissions ................................................................................................. 181
 


11.1 Black Carbon Emissions ............................................................................................................. 181
 


11.1.1 Effect of Fuel Flow Rate and Engine Thrust ......................................................................... 191
 


11.1.2 Effect of Fuel Composition .................................................................................................... 197
 


11.1.3 Effect of Engine Type ............................................................................................................ 199
 


11.1.4 Effect of Cold and Warm Engine Conditions ......................................................................... 199
 


11.1.5 Effect of Probe Position ......................................................................................................... 199
 


11.1.6 Test-Average Black Carbon Emission Index ........................................................................ 201
 


11.2 PAH Emissions ........................................................................................................................... 204
 


11.2.1 Effect of Fuel Flow Rate ........................................................................................................ 214
 


11.2.2 Effect of Fuel Composition .................................................................................................... 214
 


11.2.3 Effect of Engine Cycle ........................................................................................................... 219
 


11.2.4 Effect of Engine Type ............................................................................................................ 219
 


11.2.5 Effect of Cold and Warm Engine Conditions ......................................................................... 219
 


11.2.6 Effect of Probe Position ......................................................................................................... 223
 


11.2.7 Test-Average PAH Emission Index ....................................................................................... 224
 


12. Gas-Phase Chemical Composition ................................................................................................ 227
 


13. Particle-Phase Chemical Composition ........................................................................................... 237
 


13.1 Element and Ion Emissions ........................................................................................................ 237
 


13.2 Organic and Elemental Carbon Emissions ................................................................................. 244
 


iii 
13.3 Particle-Phase Organic Compounds .......................................................................................... 246
 


14. Quality Assurance .......................................................................................................................... 253
 


14.1 Data Quality Indicator Goals ....................................................................................................... 253
 


14.1.1 Photoacoustic Analysis (APEX-1) ......................................................................................... 254
 


14.1.2 Infrared CO2 Gas Analyzers (APEX-2 and APEX-3) ............................................................ 255
 


14.1.3 DQI Measurements for Volumetric Air Flow Rates ............................................................... 257
 


14.1.4 Temperature (Thermocouples) ............................................................................................. 258
 


14.1.5 DQI Measurements for Differential Pressure ........................................................................ 258
 


14.2 Post-Test Laboratory Analysis .................................................................................................... 258
 


14.2.1 Gravimetric Analysis of Teflon Filter Samples ...................................................................... 258
 


14.2.2 PM Organic Speciation Analysis ........................................................................................... 262
 


14.2.2.1 Solvent Extraction - GC/MS .......................................................................................... 262
 


14.2.2.2 Thermal Desorption – GC/MS ....................................................................................... 263
 


14.2.2.3 IC Analyses ................................................................................................................... 265
 


14.2.2.4 XRF Analyses ................................................................................................................ 265
 


14.2.2.5 EC/OC Analyses ........................................................................................................... 265
 


15. Conclusions and Recommendations .............................................................................................. 267
 


16. References ..................................................................................................................................... 271
 


List of Appendices 

Appendix A	 	 Description of the Dilution Sampling System (DSS) 

Appendix B	 	 Target Analytes and Detection Limits for SUMMA Canister Samples 

Appendix C 	 Target Carbonyl Compounds and Detection Limits for DNPH-Impregnated Silica Gel 

Cartridge Samples 

Appendix D 	 Tables for Section 8 - Particulate Matter Mass Emissions 

Appendix E	 	 Tables for Section 9 - PM Number Emissions 

Appendix F	 	 Tables for Section 10 - Particle Size Distribution and Geometric Mean Diameter 

Appendix G	 	 Tables for Section 11 - Black Carbon and PAH Emissions 

Appendix H 	 Tables for Section 13 - Particle-Phase Chemical Composition 

iv 
List of Figures 

Figure 2-1. APEX-1 experimental setup. .................................................................................................. 5
 


Figure 2-2. DEAL 30-m exhaust plume probe assembly for APEX-1. ...................................................... 6
 


Figure 2-3. Sample line enters DEAL floor downstream of horizontal slipjoint and two 45°
 


bends...................................................................................................................................... 7
 


Figure 2-4. APEX-2 experimental setup. .................................................................................................. 8
 


Figure 2-5. DEAL 30-meter exhaust plume probe assembly for APEX-2. ............................................... 9
 


Figure 2-6. APEX-3 experimental setup. ................................................................................................ 10
 


Figure 2-7. Valve arrangement used for multi-point sampling during APEX-3. ...................................... 11
 


Figure 2-8. DEAL’s “wing probe”. ........................................................................................................... 12
 


Figure 2-9. CFMI Model CFM56-2C1 jet engine tested during APEX-1. ................................................ 13
 


Figure 2-10. CFMI Model CFM56 engines: CFM56-2 (left), CFM56-3 (center), and CFM56-7
 


(right). ................................................................................................................................... 13
 


Figure 3-1. Electrical power skid used during APEX-2 and APEX-3. ..................................................... 16
 


Figure 3-2. Representative DEAL exhaust plume measurement equipment configuration, 
 

speciated test. ...................................................................................................................... 17
 


Figure 3-3. Representative DEAL background measurement equipment configuration, 
 

speciated test. ...................................................................................................................... 19
 


Figure 4-1. Open burn facility. ................................................................................................................ 45
 


Figure 4-2. Line loss sample location at probe inlet. .............................................................................. 46
 


Figure 4-3. Sampling locations for particle line loss experiments. ......................................................... 47
 


Figure 5-1. Particle loss experimental results as a function of particle size........................................... 56
 


Figure 6-1. Proposed APEX-1 EPA test cycle. ....................................................................................... 62
 


Figure 6-2. Engine operating cycles for the EPA tests during APEX-1. ................................................. 64
 


Figure 6-3. Engine operating cycles for Tests NASA-1, -1a, and -2 during APEX-1. ............................ 65
 


Figure 6-4. Engine operating cycles for Tests NASA-3, -4, and -5 during APEX-1. .............................. 66
 


Figure 6-5. Engine operating cycles for APEX-2. ................................................................................... 68
 


Figure 6-6. Operating cycles for CFM56-3B1 engines during APEX-3. ................................................. 68
 


Figure 6-7. Operating cycles for CJ610-8ATJ engine during APEX-3. .................................................. 68
 


Figure 6-8. Operating cycles for AE3007A1 engines during APEX-3. ................................................... 69
 


Figure 6-9. Operating cycles for P&W 4158 engine during APEX-3. ..................................................... 70
 


Figure 6-10. Operating cycles for RB211-535E4-B engines during APEX-3. .......................................... 71
 


Figure 7-1. Effect of fuel sulfur and aromatic content on fuel consumption during APEX-1. ................. 76
 


Figure 7-2. Effect of engine type on fuel consumption during APEX-3. ................................................. 76
 


Figure 7-3. Effect of cold and warm engine operating conditions on fuel consumption during 
 

APEX-2 and -3. .................................................................................................................... 77
 


Figure 7-4. Correlation between CO2 concentration and fuel flow rate during Test NASA-1 of 
 

APEX-1................................................................................................................................. 78
 


Figure 7-5. Effects of fuel type on CO2 emissions for CFM56-2C1 engine during APEX-1. .................. 81
 


Figure 7-6. Effects of engine operation cycle on CO2 emissions for CFM56-2C1 engine during 
 

APEX-1................................................................................................................................. 81
 


Figure 7-7. Effects of cold and warm engine conditions on CO2 emissions for multiple engine 
 

types. .................................................................................................................................... 82
 


v 
Figure 8-1. PM-2.5 emission index as a function of fuel flow rate by Nano-SMPS for the 
 

CFM56-2C1 engine. Data shown are corrected for sampling line particle losses. .............. 88
 


Figure 8-2. PM-2.5 mass emission index as a function of fuel flow as determined by the Nano-
 

SMPS for: (a) APEX-2 T2; and (b) APEX-2 T4. Data corrected for sampling line 
 

Figure 8-3. PM-2.5 mass emission index as a function of fuel flow rate as determined by the
 


Nano-SMPS for the CJ610-8ATJ jet engine in APEX-3 T5. Data shown are 
 

Figure 8-4. PM-2.5 mass emission index as a function of fuel flow rate as determined by the
 


Nano-SMPS for the AE3007A1/1 jet engine in APEX-3 T10. Data shown are 
 

Figure 8-5. PM-2.5 mass emission index as a function of fuel flow rate as determined by the
 


Nano-SMPS for P&W 4158 jet engine in APEX-3 T6 and T7. Data shown are 
 

Figure 8-6. PM-2.5 mass emission index as a function of fuel flow rate as determined by the
 


Nano-SMPS for RB211-535E4-B jet engine in APEX-3 T8 and T9. Data shown are 
 

Figure 8-7. Effect of engine operating mode on PM-2.5 mass emissions for a CFM56-3B1
 


Figure 8-8. Effect of engine operating mode on particle mass emissions for a CJ610-8ATJ 
 

Figure 8-9. Effect of engine operating mode on particle mass emissions for an AE3007A1/1 
 

Figure 8-10. Effect of engine operating mode on particle mass emissions for a RB211-535E4-B 
 

Figure 8-11. Effects of fuel type on: (a) mass emission index (CFM56-2C1) and (b) mass EI as a
 


function of fuel sulfur (all CFM56 derivatives). Based on Nano-SMPS loss-
 

Figure 8-12. Effect of engine type on the PM-2.5 mass emission index for ICAO LTO power 
 

Figure 8-14. Comparison of the mass emissions indices between the Nano-SMPS and EEPS for 
 

Figure 8-15. Comparison of the mass emissions indices between the Nano-SMPS and TEOM 
 

Figure 8-16. Comparison of the mass emissions indices between the Nano-SMPS and QCM for: 
 

loss. ...................................................................................................................................... 89
 


corrected for sampling line particle losses. .......................................................................... 90
 


corrected for sampling line particle losses. .......................................................................... 91
 


corrected for sampling line particle losses. .......................................................................... 91
 


corrected for sampling line particle losses. .......................................................................... 92
 


engine. Based on Nano-SMPS loss corrected data............................................................. 93
 


turbojet engine. Based on Nano-SMPS loss-corrected data. .............................................. 94
 


engine. Based on Nano-SMPS loss-corrected data. ........................................................... 94
 


engine. Based on Nano-SMPS loss corrected data............................................................. 95
 


corrected results................................................................................................................... 97
 


conditions. Based on the line loss corrected Nano-SMPS results....................................... 99
 


Figure 8-13. Effect of cold and warm engine temperature on PM mass emission index. ...................... 100
 


different tests. ..................................................................................................................... 101
 


for different tests in APEX-2 and -3.................................................................................... 102
 


(a) APEX-2 tests and (b) APEX-3 tests. ............................................................................. 103
 


Figure 8-17. Effects of fuel type on test-average PM mass emission index from the Teflon filter 
 

Figure 8-18. Effects of engine type on test-average PM mass emission index from the Teflon
 


filter integrated sampling. Note that the percent volatile fraction is also shown in the
 


Figure 8-19. Comparison of the test-average emission indices between Teflon filter and Nanofor APEX-1 tests. Note that the percent volatile fraction is also shown in the figure. ........ 107
 


figure................................................................................................................................... 107
 


SMPS measurements. ....................................................................................................... 108
 


vi 
Figure 9-1. Particle number emission indices as a function of fuel flow as determined by the
 


Nano-SMPS during APEX-1 for: (a) base fuel; (b) high-sulfur fuel; and (c) high-
 

aromatic fuel....................................................................................................................... 111
 


Figure 9-2. Particle number emission indices as a function of fuel flow as determined by the
 


Nano-SMPS for two CFM56 engine models during: (a) APEX-2 T2; (b) APEX-3 
 

Figure 9-3. Particle number emission index as a function of fuel flow rate as determined by the 
 

Nano-SMPS for the CJ10-8ATJ turbojet engine. Data shown are corrected for 
 

Figure 9-4. Particle number emission index as a function of fuel flow as determined by the 
 

Nano-SMPS for: AE3007A1E; and AE3007A1/1 engines. Data are corrected for 
 

Figure 9-5. Particle number emission index as a function of fuel flow as determined by the 
 

Nano-SMPS for a PW4158 engine during: Test 6; and Test 7 of APEX-3. Data are 
 

Figure 9-6. Particle number emission index as a function of fuel flow as determined by the 
 

Nano-SMPS for two different RB211-535E4B engines during: Test 8; and Test 9 of
 


Figure 9-7. Logarithmic correlation between particle number emission index measured by 
 

Figure 9-8. Effects of fuel type on particle number emissions index as determined during
 


Figure 9-10. Particle number emission index as a function of fuel flow (power) for different 
 

Figure 9-11. Comparison of particle number emission indices for different engines at: idle; take-
 

Figure 9-12. Comparison of particle number emission indices by EEPS for different engines 
 

Figure 9-14. Comparison of particle number emission indices as obtained from the Nano-SMPS 
 

Figure 9-15. Comparison of particle number emission indices as obtained from the Nano-SMPS 
 

Figure 10-1. Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-1, (a) with
 


Figure 10-2. Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-2, (a) with
 


Figure 10-3. Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-3, (a) with
 


Figure 10-4. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-1, (a) with
 


Figure 10-5. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-1a, (a) 
 

Figure 10-6. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-2, (a) with
 


T11; and (c) APEX-2 T4. Data shown are corrected for line losses. ................................. 112
 


sampling line particle losses. ............................................................................................. 113
 


particle line losses.............................................................................................................. 114
 


corrected for particle line losses......................................................................................... 115
 


APEX-3. Data are corrected for particle line losses. .......................................................... 116
 


EEPS and fuel flow rate. .................................................................................................... 117
 


APEX-1 (Nano-SMPS). ...................................................................................................... 118
 


Figure 9-9. Particle number emission index as a function of fuel sulfur for all CFM56 variants. ......... 119
 


engines (Nano-SMPS). ...................................................................................................... 121
 


off; climb-out; and approach power (Nano-SMPS). ........................................................... 122
 


under the idle power condition. .......................................................................................... 123
 


Figure 9-13. Effect of engine operating temperature on particle number emission index. ..................... 123
 


and EEPS instruments. ...................................................................................................... 124
 


and long DMA SMPS. ........................................................................................................ 125
 


line loss correction; and (b) without line loss correction. .................................................... 129
 


line loss correction; and (b) without line loss correction. .................................................... 130
 


line loss correction; and (b) without line loss correction. .................................................... 131
 


line loss correction; and (b) without line loss correction. .................................................... 132
 


with line loss correction; and (b) without line loss correction. ............................................ 133
 


line loss correction; and (b) without line loss correction. .................................................... 134
 


vii 
Figure 10-7. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-3, (a) with 

line loss correction; and (b) without line loss correction. .................................................... 135 

Figure 10-8. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-4, (a) with 

line loss correction; and (b) without line loss correction. .................................................... 136 

Figure 10-9. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-5, (a) with 

line loss correction; and (b) without line loss correction. .................................................... 137 

Figure 10-10. Average PSD for a CFM56-7B24 engine measured by the Nano-SMPS during 

APEX-2, Test T1, (a) with line loss correction; and (b) without line loss correction........... 138 

Figure 10-11. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during 

APEX-2, Test T2, (a) with line loss correction; and (b) without line loss correction........... 139 

Figure 10-12. Average PSD for a CFM56-3B2 engine measured by the Nano-SMPS during 

APEX-2, Test T3, (a) with line loss correction; and (b) without line loss correction........... 140 

Figure 10-13. Average PSD for a CFM56-7B24 engine measured by the Nano-SMPS during 

APEX-2, Test T4, (a) with line loss correction; and (b) without line loss correction........... 141 

Figure 10-14. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during 

APEX-3, Test T1, (a) with line loss correction; and (b) without line loss correction........... 142 

Figure 10-15. Average PSD for a CJ610-8ATJ turbojet engine measured by the Nano-SMPS 

during APEX-3, Test T2, (a) with line loss correction; and (b) without line loss 

correction. ........................................................................................................................... 143 

Figure 10-16. Average PSD for an AE3007-A1E engine measured by the Nano-SMPS during 

APEX-3, Test T3, (a) with line loss correction; and (b) without line loss correction........... 144 

Figure 10-17. Average PSD for an AE3007-A1E engine measured by the Nano-SMPS during 

APEX-3, Test T4, (a) with line loss correction; and (b) without line loss correction........... 145 

Figure 10-18. Average PSD for a CJ610-8ATJ turbojet engine measured by the Nano-SMPS 

during APEX-3, Test T5, (a) with line loss correction; and (b) without line loss 

correction. ........................................................................................................................... 146 

Figure 10-19. Average PSD for a PW4158 engine measured by the Nano-SMPS during APEX-3, 

Test T6, (a) with line loss correction; and (b) without line loss correction. ........................ 147 

Figure 10-20. Average PSD for a PW4158 engine measured by the Nano-SMPS during APEX-3, 

Test T7, (a) with line loss correction; and (b) without line loss correction. ........................ 148 

Figure 10-21. Average PSD for a RB211-535E4B engine measured by the Nano-SMPS during 

APEX-3, Test T8, (a) with line loss correction; and (b) without line loss correction........... 149 

Figure 10-22. Average PSD for a RB211-535E4B engine measured by the Nano-SMPS during 

APEX-3, Test T9, (a) with line loss correction; and (b) without line loss correction........... 150 

Figure 10-23. Average PSD for an AE3007-A1/1 engine measured by the Nano-SMPS during 

APEX-3, Test T10, (a) with line loss correction; and (b) without line loss correction. ....... 151 

Figure 10-24. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during 

APEX-3, Test T11, (a) with line loss correction; and (b) without line loss correction. ....... 152 

Figure 10-25. Effects of line particle loss correction on PSD for a CFM56-2C1 during APEX-1 

(Nano-SMPS results). ........................................................................................................ 153 

Figure 10-26. Comparison of total particle number, GMD and GSD before and after loss 

correction for all tests conducted based on: (a) total particle concentration and (b) 

GMD and (c) GSD. ............................................................................................................. 154 

Figure 10-27. Two typical results of GMD as a function of fuel flow rate for (a) a CFM56-2C1 

engine during APEX-1, Test EPA-2; and (b) for a CFM56-3B1 engine during APEX3, Test T1. .......................................................................................................................... 156 

viii 
Figure 10-28. The (a) GMD and (b) GSD of the PM emissions measured during APEX-1 for a 

CFM56-2C1 engine as a function of fuel flow. ................................................................... 157
 


Figure 10-29. The (a) GMD and (b) GSD of the PM emissions measured for three derivatives of 
 

the CFM56 engine during APEX-2 as a function of fuel flow. Engines operated 

during cold portion of test cycle.......................................................................................... 158
 


Figure 10-30. The (a) GMD and (b) GSD of the PM emissions measured for three derivatives of 
 

the CFM56 engine during APEX-2 as a function of fuel flow. Engines operated 

during warm portion of test cycle. ...................................................................................... 159
 


Figure 10-31. The (a) GMD and (b) GSD of the PM emissions measured for the small engines 
 

during APEX-3 as a function of fuel flow. Engines operated during the cold portion 

of the test cycle. ................................................................................................................. 160
 


Figure 10-32. The (a) GMD and (b) GSD of the PM emissions measured for the large engines 
 

during APEX-3 as a function of fuel flow. Engines operated during the cold portion 

of the test cycle. ................................................................................................................. 161
 


Figure 10-33. The (a) GMD and (b) GSD of the PM emissions measured for the small engines 
 

during APEX-3 as a function of fuel flow. Engines operated during the warm portion 

of the test cycle. ................................................................................................................. 162
 


Figure 10-34. The (a) GMD and (b) GSD of the PM emissions measured for the large engines 
 

during APEX-3 as a function of fuel flow. Engines operated during the warm portion 

of the test cycle. ................................................................................................................. 163
 


Figure 10-35. Comparison of: (a) GMD and (b) GSD under four ICAO power conditions for 
 

different engine types......................................................................................................... 164
 


Figure 10-36. Effects of fuel type on PSD for different engine power conditions during APEX-1 
 

Figure 10-37. Comparison of the loss-corrected: (a) GMDs; and (b) GSDs for different power 
 

for: (a) idle (7%), (b) climb-out (85%), and (c) approach (30%)......................................... 166
 


conditions and fuels during APEX-1. .................................................................................. 167
 


Figure 10-38. Comparison of GMDs for different engines........................................................................ 168
 


Figure 10-39. Comparison of GSDs for different engines. ....................................................................... 169
 


Figure 10-40. Comparison of GMD produced by different engines at: (a) idle, (b) takeoff, (c) 
 

climb, and (d) approach power........................................................................................... 170
 


Figure 10-41. Comparison of GSD produced by different engines at: (a) idle, (b) takeoff, (c) climb, 
 

Figure 10-42. Effect of engine operating temperature on: (a) PM number concentration; (b) GMD; 
 

and (d) approach power. .................................................................................................... 171
 


and (c) GSD. ...................................................................................................................... 173
 


Figure 10-43. Comparisons of: (a) particle number concentration; (b) GMD; and (c) GSD 
 

measured by the 15- and 30-m probes during APEX-3 T5 (Nano-SMPS; line-loss 

corrected). .......................................................................................................................... 174
 


Figure 10-44. Comparisons of: (a) particle number concentrations; (b) GMD; and (c) GSD 
 

measured by the 30- and 43-m probes during APEX-3 T8 (EEPS; line-loss 

corrected). .......................................................................................................................... 176
 


Figure 10-45. Effects of probe position on particle number emission indices for a: CJ610-8ATJ 
 

turbojet; and RB211-535E4B turbofan engine. .................................................................. 177
 


Figure 10-46. Effects of probe position on particle mass emission indices for a: CJ610-8ATJ 
 

Figure 10-47. Comparison of the GMD and GSD as obtained from Nano-SMPS and EEPS 
 

turbojet; and RB211-535E4B turbofan engine. .................................................................. 178
 


measurements during all tests conducted during APEX-2 and -3. .................................... 180
 


ix 
Figure 11-1. Time-series black carbon concentration data for the tests EPA-1, EPA-2, NASA-1, 
 

and NASA-1a of APEX-1 campaign for the CFM56-2C1 engine with base fuel. ............... 182
 

Figure 11-2. Time-series black carbon concentration data for the tests NASA-4 and NASA-5 of 
 

APEX-1 campaign for the CFM56-2C1 engine with high-aromatic fuel. ............................ 183
 

Figure 11-3. Time-series black carbon concentration data for the tests T1 and T4 of APEX-2 
 

campaign for the CFM56-7B24 engine. ............................................................................. 184
 

Figure 11-4. Time-series black carbon concentration data for the tests T2 and T3 of APEX-2 
 

and T1 and T11 of APEX-3 for the CFM56-3B series engine............................................ 185
 

Figure 11-5. Time-series black carbon concentration data for the APEX-3 T2 and T5 for the 
 

CJ610-8ATJ turbojet engine. ............................................................................................. 186
 

Figure 11-6. Time-series black carbon concentration data for the APEX-3 T3 and T4 for the 
 

AE3007A1E engine and T10 for the AE3007A1/1 engine. ................................................ 187
 

Figure 11-7. Time-series black carbon concentration data for the APEX-3 T6 and T7 for the 
 

P&W 4158 engine. ............................................................................................................. 188
 

Figure 11-8. Time-series black carbon concentration data for the APEX-3 T8 and T9 for the 
 

RB211-535E4-B engine. .................................................................................................... 189
 

Figure 11-9. Black carbon emission index as a function of fuel flow rate for the CFM56-2C1
 

engine during APEX-1. ....................................................................................................... 192
 

Figure 11-10. Black carbon emission index as a function of fuel flow rate for the CFM56-7B24 
 

engine. ................................................................................................................................ 193
 

Figure 11-11. Black carbon emission index as a function of fuel flow rate for the CFM56-3B series 
 

engine. ................................................................................................................................ 193
 

Figure 11-12. Black carbon emission index as a function of fuel flow rate for the CJ610-8ATJ 
 

turbojet engine. ................................................................................................................... 194
 

Figure 11-13. Black carbon emission index as a function of fuel flow rate for the AE3007A1/1
 

engine.Figure 11-14. Black carbon emission index as a function of fuel flow rate for 

the P&W 4158 engine. ....................................................................................................... 194
 

Figure 11-14. Black carbon emission index as a function of fuel flow rate for the P&W 4158
 

engine. ................................................................................................................................ 195
 

Figure 11-15. Black carbon emission index as a function of fuel flow rate for the RB211-535E4B 
 

engine. ................................................................................................................................ 195
 

Figure 11-16. Effect of engine cycle on BC emission index for multiple engine types. ............................ 197
 

Figure 11-17. Comparison of black carbon emission indices obtained from different types of fuel 
 

for the CFM56-2C1 engine during APEX-1........................................................................ 198
 


Figure 11-18. Effect of sulfur content in fuel on BC emission index for all CFM56 engines tested.......... 198
 


Figure 11-19. Effect of engine type on BC emission index for multiple engine types. ............................. 200
 


Figure 11-20. Effect of engine cold and warm condition on BC emission index. ..................................... 201
 


Figure 11-21. Effect of probe position on BC emission index for the CJ610-8ATJ and 
 

RB211-535E4B engines. .................................................................................................... 202
 

Figure 11-22. Time-series PAH concentration data for tests EPA-1, EPA-2, NASA-1, and NASA1a of APEX-1 campaign for the CFM56-2C1 engine with base fuel. ................................. 205
 

Figure 11-23. Time-series PAH concentration data for tests NASA-4 and NASA-5 of APEX-1 
 

campaign for the CFM56-2C1 engine with high-aromatic fuel. .......................................... 206
 

Figure 11-24. Time-series PAH concentration data for tests T1 and T4 of APEX-2 campaign for 
 

the CFM56-7B24 engine. ................................................................................................... 207
 


x 
 
Figure 11-25. Time-series PAH concentration data for tests T2 and T3 of APEX-2 and T1 and 

T11 of APEX-3 for the CFM56-3B series engines. ............................................................ 208
 


Figure 11-26. Time-series PAH concentration data for the APEX-3 T2 and T5 for the CJ610-8ATJ
 


turbojet engine. ................................................................................................................... 209
 


Figure 11-27. Time-series PAH concentration data for the APEX-3 T3 and T4 for the AE3007A1E
 


engine and T10 for the AE3007A1/1 engine...................................................................... 210
 


Figure 11-28. Time-series PAH concentration data for the APEX-3 T6 and T7 for the P&W 4158 
 

engine................................................................................................................................. 211
 


Figure 11-29. Time-series PAH concentration data for the APEX-3 T8 and T9 for the RB211­

535E4-B engine. ................................................................................................................. 212
 


Figure 11-30. PAH emission index as a function of fuel flow for the CFM56-2C1 engine while 
 

burning: (a) base fuel; and (b) high-aromatic fuel. ............................................................. 215
 


Figure 11-31. PAH emission index as a function of fuel flow for CFM56-7B24 engines. ......................... 216
 


Figure 11-32. PAH emission index as a function of fuel flow for CFM56-3B series engines. .................. 216
 


Figure 11-33. PAH emission index as a function of fuel flow for the CJ610-8ATJ turbojet engine. ......... 217
 


Figure 11-34. PAH emission index as a function of fuel flow for the AE3007-A1/1 engine...................... 217
 


Figure 11-35. PAH emission index as a function of fuel flow for the PW4158 engine. ............................ 218
 


Figure 11-36. Comparison of PAH emission indices for different fuel types during APEX-1. .................. 218
 


Figure 11-37. Effect of engine power on the PAH emission index for different engine types. ................. 221
 


Figure 11-38. Effect of engine type on (a) idle, (b) take-off, (c) climb-out and (d) approach PAH 
 

emissions. .......................................................................................................................... 222
 


Figure 11-39. Effect of engine operating temperature on PAH emissions. .............................................. 223
 


Figure 11-40. Effect of probe position on PAH emission index for the CJ610-8ATJ engine during
 


APEX-3............................................................................................................................... 224
 


Figure 11-41. Comparison of the average PAH emission indices obtained from the tests with 
 

different types of jet engines. ............................................................................................. 226
 


Figure 12-1. Mass EIs of individual NMVOCs from SUMMA canister sampling. ................................... 231
 


Figure 12-2. Mass EIs of individual carbonyl compounds from DNPH cartridge sampling.................... 233
 


Figure 12-3. Emission indices of total NMVOCs and carbonyls for different engines............................ 234
 


Figure 12-4. Comparison of EIs for individual gas phase species as produced by different 
 

engine types. ...................................................................................................................... 235
 


Figure 13-1. Elemental emission indices for each test. .......................................................................... 238
 


Figure 13-2. Comparison of elemental emission indices for different engines....................................... 239
 


Figure 13-3. Correlation of sulfur emission index with fuel sulfur content for CFM56 engines. ............. 241
 


Figure 13-4. Water-soluble ion emission indices for each test. .............................................................. 242
 


Figure 13-5. Comparison of water-soluble ion emission indices for different engines........................... 243
 


Figure 13-6. Correlation of SO4 emission index with fuel sulfur content for CFM56 engines. ............... 244
 


Figure 13-7. Comparison of OC and EC emission indices for: (a) organic carbon; and 
 

(b) elemental carbon. ......................................................................................................... 247
 


Figure 13-8. Relative contribution of individual organic compounds to the total speciated
 


Figure 13-9. Relative contribution of classes of organic compounds to the total speciated
 


Figure 13-10. Effects of quartz-filter sampling-artifact correction on emission indices of individual
 


particle-phase EI. ............................................................................................................... 248
 


particle-phase EI. ............................................................................................................... 249
 


organic groups: (a) before backup correction; and (b) after backup correction................. 250
 


xi 
Figure 13-11. Effects of background correction on emission indices of individual organic groups 

for: (a) n-Alkanes; and (b) PAHs. ....................................................................................... 251
 


Figure 14-1. Sample losses from the comparison of weights measured on 1/16/06 and 1/20/06. ........ 262
 


List of Tables 

Table 2-1. Engines Tested in APEX-1, -2 and -3 .................................................................................. 14
 


Table 3-1. Specifications of the DEAL ................................................................................................... 15
 


Table 3-2. Measurement Configuration for the Plume Sample Tunnel................................................. 20
 


Table 3-3. Measurement Configuration for the Background Sample Tunnel ........................................ 21
 


Table 3-4. Measurements Performed by the DEAL during APEX-1, -2, and -3.................................... 22
 


Table 4-1. General Analytical Plan ........................................................................................................ 30
 


Table 4-2. PM Instrument Calibration Schedule.................................................................................... 32
 


Table 4-3. Gas Analyzer Calibration Schedule ..................................................................................... 32
 


Table 4-4. Available MOPs for On-Line Analyzers ................................................................................ 33
 


Table 4-5. Field Sampling Equipment QC Checks ................................................................................ 34
 


Table 4-6. Photoacoustic Analyzer Response Checks Performed during APEX-1 .............................. 36
 


Table 4-7. Analytical Procedures for Chemical Characterization .......................................................... 38
 


Table 4-8. GC, MS and TD Operating Conditions ................................................................................. 41
 


Table 4-9. Particle Line Loss Sampling Location Descriptions and Sequence ..................................... 47
 


Table 5-1. Particle Loss Penetration Equations Obtained from the EEPS Measurementsa

 ................. 56
 


Table 6-1. APEX Test Matrix ................................................................................................................. 60
 


Table 6-2. Composition of Fuel Used in APEX Campaigns .................................................................. 61
 


Table 7-1. Average and Relative Standard Deviation of Wind Speed and Direction for 
 

Individual Tests .................................................................................................................... 73
 


Table 7-2. Summary of Fuel Flow Rates Measured at Different Engine Power Levels ........................ 75
 


Table 7-3. Average Background Corrected CO2 Concentrations at Different Power Settings for 
 

APEX-1 and -2 ..................................................................................................................... 79
 


Table 7-4. Average Background Corrected CO2 Concentrations at Different Power Settings for 
 

APEX-3................................................................................................................................. 80
 


Table 7-5. Test-Average Background Corrected CO2 Concentrations for Each Test........................... 83
 


Table 8-1. Particle Loss Correction Coefficient Determined from Nano-SMPS Measurements 
 

for Each Test ........................................................................................................................ 86
 


Table 8-2. Effect of Engine Power on Average Emission Index for Different Engines .......................... 93
 


Table 8-3. Comparison of Emission Indices by Different Type of Fuels (Based on Nano-SMPS 
 

particle loss-corrected results) ............................................................................................. 96
 


Table 8-4. Comparison of Instruments Used for Mass Emissions Measurements ............................. 104
 


Table 8-5. Test-Average PM Mass Emission Indices Derived from Measurements of Various 
 

Instruments ......................................................................................................................... 106
 


Table 9-1. Particle Number Emission Indices at Each of Four Engine Power Settings for 
 

Different Engines (Nano-SMPS results) ............................................................................. 121
 


Table 11-1. Black Carbon Monitoring in APEX Tests............................................................................ 190
 


Table 11-2. BC Emission Indices at the LTO Power Levels for Different Engines ............................... 196
 


Table 11-3. Test-average PM and BC EIs and BC Fraction in PM ....................................................... 203
 


xii 
Table 11-4. PAH Monitoring in APEX Tests .......................................................................................... 213
 


Table 11-5. PAH Emission Indices at the Four ICAO Engine Power Levels for Different Engines....... 220
 


Table 11-6. Comparison between the PAH Emission Indices Obtained by the PAS 2000 
 

Measurements and the Quartz Filter Integrated Sampling ................................................ 225
 


Table 12-1. Emission Indices of Individual VOCs Obtained by SUMMA Sampling for Different 
 

Engines............................................................................................................................... 228
 


Table 12-2. Emission Indices of Individual Carbonyl Compounds Obtained by DNPH Sampling
 


for Different Engines ........................................................................................................... 232
 


Table 12-3. Comparison of NMVOC and Carbonyl Emission Indices for Different Engines ................. 233
 


Table 13-1. Total Elemental Emission Index Derived from the XRF Analyses ..................................... 238
 


Table 13-2. Elemental Emission Indices for Different Engines ............................................................. 239
 


Table 13-3. Sulfur Emission Indices for Individual Tests as Determined from the XRF Analyses 
 

and Their Associated Fuel Sulfur Contents ........................................................................ 241
 


Table 13-4. Water Soluble Ion Emission Indices Derived from the IC Analyses for Each Test............ 242
 


Table 13-5. Water Soluble Ion Emission Indices for Different Engines ................................................. 243
 


Table 13-6. Sulfate Emission Indices from the IC Analyses and Their Fuel Sulfur Contents ............... 244
 


Table 13-7. Organic and Elemental Carbon Emission Indices for Each Test ....................................... 245
 


Table 13-8. Organic Carbon and Elemental Carbon Emission Indices for Different Engines ............... 246
 


Table 14-1. DQI Goals for DEAL Instrumentation ................................................................................. 253
 


Table 14-2. INNOVA 1314 Photoacoustic Multigas Analyzer Calibrations ........................................... 254
 


Table 14-3. DQI Values for Photoacoustic Analyzer Gas Measurements for All Tests ........................ 254
 


Table 14-4. Carbon Dioxide Analyzer Calibrations ............................................................................... 255
 


Table 14.5 DQI Values for Infrared CO2 Gas Analyzer Measurements for All Tests ........................... 256
 


Table 14.6 Variations in Environmental Conditions and Balance Stability for APEX-3 Teflon 
 

Filter Gravimetric Analysis.................................................................................................. 259
 


Table 14-7. Standard Deviation of Replicate Tare Weight Measurement for Each of APEX-3 
 

Teflon Filters ....................................................................................................................... 260
 


Table 14-8. Replicate Final Weight Measurement for Each APEX-3 Teflon Filter ................................ 261
 


Table 14-9. Recoveries of Individual Components by Solvent Extraction Analysis .............................. 264
 


Table 14-10. Relative Standard Deviation in IC Measurements ............................................................. 265
 


xiii 
xiv 

List of Acronyms, Initializations, and Abbreviations 

40CFR Title 40 of the Code of Federal Regulations 

acfm actual ft3

/min 

AEC Aircraft Emissions Characterization 

AEDC U.S. Air Force’s Arnold Engineering Development Center 

AIM Aerosol Instrument Manager 

APEX Aircraft Particle Emissions eXperiment 

ARCADIS ARCADIS U.S., Inc. 

ARI Aerodyne Research, Inc. 

B&K Brüel and Kjær 

BC black carbon 

CD compact disc 

CFMI CFM International 

C/O climb-out 

CO carbon monoxide 

CO2 carbon dioxide 

CPC condensation particle counter 

CPU central processing unit 

DAS data acquisition system 

DEAL Diesel Emissions Aerosol Laboratory 

DFRC Dryden Flight Research Center 

DI deionized 

DMA differential mobility analyzer 

DNPH 2,4-dinitrophenylhydrazine 

DQI data quality indicator 

DSS dilution sampling system 

EC elemental carbon 

EEPS engine exhaust particle sizer 

EI emission index 

ElM PM-2.5 mass emission index 

EIN PM-2.5 number emission index 
ELPI electrical low pressure impactor 

EPA U.S. Environmental Protection Agency 

EPC electronically programmable control 

ERG Eastern Research Group 

ESP electrostatic precipitator 

FAA Federal Aviation Administration 

FID flame ionization detector 

FPCL Fine Particle Characterization Laboratory 

GC/MS gas chromatography/mass spectrometry 

GMD geometric mean diameter 

GRE ground run-up enclosure 

GSD geometric standard deviation 

GVW gross vehicle weight 

H2O water 

HAP hazardous air pollutant 

HEPA High-Efficiency Particulate Air 

Hg mercury 

HP Hewlett-Packard 

HPLC high performance liquid chromatography 

I/O input/output 

IC ion chromatography 

ICAO International Civil Aviation Organization 

ID inside diameter 

IR infrared 

KVM keyboard-video-monitor 

LTO landing and take-off 

MDL method detection limit 

MFC mass flow controllers 

MnO2 manganese dioxide 

MOP(s) miscellaneous operating procedure(s) 

MSD mass selective detection 

NAAQS National Ambient Air Quality Standard 

xv 
NaCI sodium chloride 

NASA National Aeronautics and Space Administration 

NERL National Exposure Research Laboratory 

NIOSH National Institute for Occupational Safety and Health 

NIST National Institute of Standards and Technology 

NMOC nonmethane organic compound 

NMVOC nonmethane volatile organic compound 

NOX nitrogen oxides 

NRMRL National Risk Management Research Laboratory 

OC organic carbon 

OD outside diameter 

OTAQ Office of Transportation and Air Quality 

PA photoacoustic analyzer 

PAH polycyclic aromatic hydrocarbon 

PAS photoelectric aerosol sensor 

PM particulate matter 

PM-2.5 particles ≤2.5 μm in aerodynamic diameter 

PQL practical quantitation limit 

PSD particle size distribution 

PTV programmable temperature vaporizing 

PUF polyurethane foam 

QA quality assurance 

QAPP quality assurance project plan 

QC quality control 

QCM quartz crystal microbalance 

R2

 correlation coefficient 

R&P Rupprecht and Patashnick 

RSD relative standard deviation 

RTP Research Triangle Park 

SAE Society of Automotive Engineers 

SD standard deviation 

SIP State Implementation Plan 

xvi 
SM smoke number 

SMPS scanning mobility particle sizer 

SN smoke number 

SNMOC speciated non-methane organic compound 

SOP standard operating procedure 

SUMMA SUMMA-polished stainless steel canisters 

SVOC(s) semi-volatile organic compound(s) 

T/O take-off 

TCD thermal conductivity detector 

TD thermal desorption 

TEOM tapered element oscillating microbalance 

THC total hydrocarbons 

TWA time-weighted average 

UMR Missouri University of Science and Technology Center of Excellence 

UPS uninterruptible power supply 

UV ultraviolet 

VOC volatile organic compound 

XRF x-ray fluorescence 

xvii 
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Executive Summary 

The fine particulate matter (PM) emissions from aircraft operations at large airports located in areas of the 

U. S. designated as non-attainment for the National Ambient Air Quality Standard (NAAQS) for PM-2.5 

(particles <2.5 μm in aerodynamic diameter) are of major environmental concern. In general, the majority 

of the available PM emissions data for commercial aircraft engines is limited and does not completely 

characterize volatile components resulting from atmospheric cooling and dilution. There is, therefore, the 

need for a comprehensive PM emissions database for aircraft turbine engines which includes massbased emission factors and chemical speciation data, and which also relates the PM emissions to key 

engine operating parameters and fuel characteristics. 

To address the need for improved aircraft PM emissions data, the Aircraft Particle Emissions eXperiment 

(APEX) was organized in 2003. The APEX program is a major collaborative effort between the National 

Aeronautics and Space Administration (NASA) and a number of other research organizations including 

the U.S. Environmental Protection Agency’s (EPA’s) National Risk Management Research Laboratory 

(NRMRL) in Research Triangle Park, North Carolina. The objectives of the three APEX sampling 

campaigns (APEX-1, -2, and -3) were to update and improve emission factors (indices) and chemical 

source profiles for aircraft-generated fine PM and, if possible, to assess the effect of fuel properties (e.g., 

sulfur content) and engine operating conditions (e.g., cold vs. warm) on PM formation. 

During APEX-1, -2 and -3, ground level measurements were conducted by EPA in the engine exhaust 

plume, primarily at a single point located a distance of 30 m behind the engine exit. The system was 

configured as a beveled nozzle connected to a 5-cm outside diameter (OD) polished stainless steel 

sampling line that ran from the plume centerline to the inlet of EPA’s Diesel Emissions Aerosol Laboratory 

(DEAL) instrumented sampling tunnel. Thoroughly cleaned stainless steel tubing and uncontaminated 

fittings were used for the entire system. The sampling probe was constructed from 5-cm diameter 

stainless steel tubing with a tapered inlet nozzle which was attached to a rigid stand anchored to the 

tarmac. The exact length and configuration of the sampling line running from the probe to the DEAL 

depended on the engine type and sampling campaign. 

The DEAL uses two centrifugal blowers, each controlled by a variable frequency drive and mass flow 

meter, to continuously extract 1.1 (actual) m3

 min-1 of sample gas from the plume. After extraction, the 

plume sample flows through a 5-cm diameter stainless steel sampling tube into a PM-2.5 “cut point” (i.e., 

particle diameter representing a 50% collection efficiency for equivalent unit density spheres ≤2.5 μm in 

aerodynamic diameter) virtual impactor, and then into an 8.8-m long, 15-cm inside diameter (ID) stainless 

steel sampling tunnel. A series of “buttonhook” stack sampling nozzles, staggered in height inside the 

tunnel to minimize aerodynamic interference, is used to extract samples from the tunnel. The sample flow 

captured by each nozzle exits the sampling tunnel through custom designed four-way flow splitters that 

direct the flow from the tunnel to the various instruments. Either grounded stainless steel or conductive 

xix 
 

silicone rubber lines connect the instruments to the appropriate sample splitter. A similar sampling system 

was also used for determination of the ambient background. 

The DEAL was outfitted and configured to accommodate the sample collection and continuous monitoring 

requirements of the APEX monitoring plan. Both continuous monitoring and time-integrated sampling 

were conducted during the three APEX campaigns for both particle- and gas-phase air pollutants. 

Continuous monitoring was conducted for PM mass and number concentration, particle size distribution, 

black carbon, particle surface polycyclic aromatic hydrocarbons, carbon dioxide, carbon monoxide 

(APEX-1), total volatile organic compounds (APEX-1), plume temperature and velocity (APEX-2), and 

ambient wind speed/direction. Time-integrated sampling was also performed for PM mass concentration 

(Teflon filter), total volatile PM (i.e., Teflon filter sampling downstream of a thermal denuder), 

elemental/organic carbon, speciated semivolatile organic compounds, speciated water-soluble ions, 

elemental composition, gas-phase nonmethane volatile organic compounds, and gas-phase carbonyls. 

Emission indices (factors) were calculated from the experimental data in terms of mass (or number) of 

pollutant per mass of fuel burned using a carbon balance involving the percent carbon in the fuel 

determined by fuel analysis and the concentration of carbon dioxide measured in the sample stream (note 

that CO and total hydrocarbons are generally insignificant compared to CO2). The experimental data are 

always presented in terms of the engine fuel flow recorded during each test, but sometimes are shown 

relative to nominal percent rated thrust for ease of comparison between different engine types. 

There was a total of 24 tests conducted during the three APEX campaigns. A CFM56-2C1 engine 

mounted on a DC-8 airframe was used throughout the nine APEX-1 tests to investigate the effects of fuel 

composition on emissions at various power settings. Three types of fuel were used: a base fuel (JP-8 or 

Jet-A1), a high-sulfur fuel (JP-8 doped with approximately four times the sulfur content of the base fuel), 

and a higher-aromatic JP-8. 

During APEX-2 and -3, each engine was run with the available Jet-A fleet fuel it would use during normal 

commercial operations. The same engine family used during APEX-1, the CFM56 mounted on B737 

airframes, was also included in all four APEX-2 tests and two of the eleven APEX-3 tests. These tests 

provided further characterization of the fine particulate emissions from these widely-used jet engines. 

Five additional turbine engines of various sizes were also studied in APEX-3. These additional turbine 

engines included a General Electric CJ610-8ATJ turbojet (in use on a Lear Model 25), Rolls Royce 

AE3007A1E and AE3007A1P mixed turbofans (in use on the Embraer ERJ145), a Pratt and Whitney 

PW4158 turbofan (in use on the Airbus A300), and a Rolls Royce RB211-535E4-B mixed turbofan (in use 

on the B757). 

In general, the test engines were operated at a series of steady-state power conditions which were set for 

the ambient conditions using the expertise of the on-site engine company representative. During APEX-1, 

two engine test matrices were used. The “EPA” test matrix followed the landing and take-off (LTO) cycle 

defined by the International Civil Aviation Organization (ICAO) to simulate aircraft emissions at an airport. 

This matrix consisted of approximately four repetitions of the following power settings: 26 min at idle (7% 

rated thrust), 0.7 min at takeoff (100%), 2.2 min at climb (85%), and 4 min at approach (30%). The 

“NASA” test matrix was designed to investigate the effects of engine operating parameters on particle 

emissions and included 11 power settings. Except for the 100 percent thrust level, where run-time was 

xx 
 

limited to 1.5 min, approximately 10 min were provided at each power setting to allow for samples to be 

adequately analyzed. 

For APEX-2 and -3, the engines were operated in cycles encompassing a series of steady state power 

settings to investigate the effects of these power settings on particle emissions. The power levels 

included those used during engine certification, simulated cruise, engine start/stop, and transitions 

between throttle settings. During these tests, the thrust was changed in a stepwise fashion from the 

lowest thrust level to highest under the “cold” engine condition, and then decreased in a similar fashion 

under the “warm” engine condition. The specific power conditions and fuel flow varied slightly by both 

campaign and engine type. 

Based on the experimental data collected, the following conclusions were reached: 

•	 The testing of aircraft turbine engine emissions is difficult, requiring long sampling lines with their 

associated high residence time and particle losses. Corrections were made for particle losses, but the 

impact of the long residence time has yet to be established. 

•	 The PM mass emission index ranged from approximately 10 to 550 mg/kg of fuel burned, depending 

on engine and fuel type, operating power, and environmental conditions. 

•	 For the turbofan engines tested, the relationship of ElM (the PM-2.5 mass emission index expressed 

in particulate mass per kg of fuel burnt) to fuel flow (engine power) followed a characteristic U-shape 

with the emissions high at idle, dropping off to a minimum at mid-range power, and rising again at 

high engine thrust. 

•	 The particle number emission indices observed in the program ranged from approximately 1(10)15 to 

1(10)17 particles/kg of fuel burned, again depending on engine and fuel type, operating power, and 

environmental conditions. 

•	 For most of the turbofan engines tested, a logarithmic relationship of EIN (the PM-2.5 number 

emission index expressed in number of particles per kg of fuel burned) to fuel flow (engine power) 

was determined in the general form: 

EI = m(ln fuel flow) + b 

where 

m 	 = slope of the regression line = -2(10)15 to -3(10)16 

b 	 = intercept of the regression line = 2(10)16 to 2(10)17 

• Both ElM and EIN were found to increase with increasing fuel sulfur content. For ElM, the PM emission 

increased linearly with fuel sulfur, whereas for EIN, the increase appears to be more of an exponential 

function. 

•	 It was also observed that engine operating temperature had a measurable effect on both ElM and EIN. 

In both cases, the emissions were slightly lower (i.e., ~8%) when the engine was warm. 

xxi 
 

•	 The particle size distributions of the emissions found in the study were generally unimodal and 

lognormally distributed with electrical mobility diameters ranging from ~3 to slightly larger than 100 

nm. At higher power levels, a small accumulation mode was also observed. 

•	 Both the geometric mean diameter (GMD) and geometric standard deviation (GSD) of the particle 

size distribution (PSD) also varied with engine and fuel type, thrust, and environmental conditions. 

The GMD ranged from approximately 10 to 30 nm (electrical mobility diameter) and the GSD ranged 

from 1.4 to 2. 

•	 In general, the largest GMDs and GSDs were obtained at high power conditions. The observations 

suggest that the PSDs produced by the engines tested under power conditions of <30% rated thrust 

were unimodal and consisted of primary nuclei particles, whereas for thrust levels >85%, 

accumulation mode particles were formed, and the PSD curves became broader. 

•	 A comparison of measurement techniques for PM mass, number, and size indicated significant 

discrepancies between instruments. Of particular note is a comparison of the ElM obtained by the 

Nano-Scanning Mobility Particle Sizer (SMPS) and the time-integrated Teflon filter sampling. The 

filter-based method always produced higher values than the SMPS-based method and there was no 

linear correlation between the two techniques. 

•	 Of the various instruments used to measure PM mass, number, and size, the SMPS appears to be 

the most reliable. The lack of correlation with the filter-based technique is disturbing, however, and an 

area worthy of further investigation. 

•	 The emission indices for black carbon (BC) and particle surface-bound PAHs (polycyclic aromatic 

hydrocarbons) generally follow trends similar to ElM discussed above except that: (1) BC was always 

highest at high power, and (2) fuel composition had no measureable effect on either BC or PAH 

emissions. Note, however, that the BC and PAH on-line measurements were highly variable and 

oftentimes did not track well with power changes. 

•	 The chemical composition of the gas-phase nonmethane volatile organic compounds (NMVOCs) and 

carbonyls varied by engine type as measured on a time-integrated basis over all power conditions. 

However, significant quantities of a number of compounds listed in the Clean Air Act as hazardous air 

pollutants (HAPs) were found in some or all engines including formaldehyde, acetaldehyde, benzene, 

acrolein, toluene, and 1,3-butadiene. 

•	 The elemental composition of the PM samples collected on Teflon filters was dominated by sulfur. In 

some samples, however, significant amounts of crustal elements such as silicon were also found due 

to the resuspension of concrete cuttings generated during installation of the sampling probes and 

lines. 

•	 Sulfate was by far the most abundant water-soluble ion determined from the Teflon filter samples. 

Calculations of the transformation of S(IV) in the fuel to S(VI) indicate conversion rates in the range of 

2 to 4%, which compare favorably to the values obtained by other investigators. 

•	 The emission indices determined in the program for organic carbon (OC) and elemental carbon (EC) 

as determined from quartz filter sampling ranged from 37 to 83 mg/kg fuel for OC and 21 to 98 mg/kg 

fuel for EC, respectively. The ratio of EC to OC ranged from 0 to almost 2 depending on the engine 

type and fuel being tested. 

•	 Over 70% of the particle-phase organic compounds, also determined from the quartz filters, consisted 

of n-alkanes and PAHs. Also, of the engines tested, the CFM56-3B1 and AE3007A1E had the highest 

xxii 
emission indices of total speciated organic compounds, whereas the P&W 4158 and CFM56-7B24 

had the lowest. 

•	 The results obtained in the study are at least generally comparable to the results obtained by other 

APEX investigators. However, a report of the APEX-3 results from the other groups has not as yet 

been released. 

From the above conclusions, the following recommendations for future research are offered for 

consideration for funding: 

•	 One major issue to be resolved in future work is the effect of the sampling system on the 

experimental results. These effects include both particle losses in the sampling lines, as well as the 

potential transformation of the aerosol from the point of collection to the point of measurement. A 

standardized sampling system with well-characterized performance should be employed in all future 

testing. Also, the issue of representative plume sampling should be addressed. 

•	 The lack of good agreement between instruments is also a significant issue warranting additional 

research. Of particular importance is the lack of correlation between on-line SMPS and filter-based 

methods for determining ElM. 

•	 Although particle losses through the sampling system can be characterized using traditional aerosol 

science techniques [e.g., sodium chloride (NaCI) aerosol], a reliable soot calibration source is needed 

that is both reproducible and stable. Although work is underway under both NASA and EPA Office of 

Transportation and Air Quality sponsorship to develop the necessary calibration equipment, additional 

research and development is definitely needed in this regard. 

•	 A reliable on-line method for the direct determination of PM mass emissions is needed. Neither the 

Tapered Element Oscillating Microbalance (TEOM) nor the Quartz Crystal Microbalance (QCM) 

appears capable of conducting these measurements in a reliable manner. The TEOM is generally not 

sensitive enough and the QCM produces values higher than other methods and has limited sampling 

times due to crystal saturation. 

•	 The effect of fuel composition is also an area worthy of additional investigation. In particular, the 

further examination of the influence of sulfur and aromatics on sulfate and organic emissions is 

needed to assess the impact of future aviation fuels on local air quality and global climate change. 

•	 Further work is needed in the characterization of plume aging. To date, all measurements have been 

performed in the near-field plume < 50 m from the engine exit. Many issues related to fence-line and 

neighborhood air quality need to be addressed at distances far greater than 50 m and multiple points 

downstream. For the plume aging tests, the instrumentation should be positioned directly in the plume 

to avoid problems with long sampling lines. 

•	 Additional chemical characterization of both the gas- and particle-phase emissions by power 

condition is needed. The data provided are representative of all thrust levels during a particular test. 

However, specific data for at least the four ICAO-specified power conditions are needed in order to 

make a determination of the local air quality impacts from airports. 

xxiii 
xxiv
 

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1. Introduction 

1.1 Background 

The fine particulate matter (PM) emissions from aircraft operations at large airports in National Ambient 

Air Quality Standards (NAAQS) nonattainment areas are of major environmental concern. Like diesel 

engines, the PM emissions generated by aircraft gas turbine engines are nanometer in size, contain a 

variety of toxic air pollutants, and are carbonaceous in nature. In addition, very little chemical source 

profile data currently exist for aircraft engines; these data are critical for use in receptor modeling, which is 

used during the State Implementation Plan (SIP) development process. 

The fine PM generated from aircraft gas turbine engines can be classified into two major components, 

non-volatile and volatile PM. Non-volatile PM (or soot) is produced in the combustor and is present at 

engine exit temperature and pressure whereas volatile PM is formed in the near-field plume downstream 

of the engine through the gas-to-particle conversion of sulfur and organic gases. Total PM is the 

combination of both volatile and non-volatile components. In the true sense, total PM can only be 

characterized by sampling of the exhaust plume after natural cooling and dilution in the atmosphere. 

There is, however, considerable controversy as to the definition of volatile PM as it applies to both local 

air quality and global climate impacts. 

For a new gas turbine engine used for aero-propulsion (a jet engine), the exhaust gas emissions must 

comply with applicable regulations promulgated by the International Civil Aviation Organization (ICAO) for 

unburned total hydrocarbons (THC), carbon monoxide (CO), nitrogen oxides (NOX), and smoke number 

(SN). The current range of certifiable operating conditions includes four power (thrust) settings (7, 30, 85 

and 100%) indicative of the landing and take-off (LTO) cycle at commercial airports. Since there is 

currently no emission standard for PM, ICAO is interested in setting a certification limit for this pollutant to 

address both local air quality and global climate issues. 

In general, the majority of the available PM emissions data for commercial aircraft engines is limited and 

does not completely characterize volatile components resulting from atmospheric cooling and dilution. 

There is, therefore, a real need for a comprehensive emissions data set for aircraft turbine engines. 

These data need to include mass-based emission factors and chemical speciation data, which relate the 

PM emissions to engine operating parameters and key fuel characteristics. This data set must also 

consider the formation of volatile components in the near-field plume. 

To address the need for better PM emissions data for aircraft, the Aircraft Particle Emissions eXperiment 

(APEX) was organized in 2003. The APEX program is a major collaborative effort between the National 

Aeronautics and Space Administration (NASA) and a number of other research organizations including 

the U.S. Environmental Protection Agency’s (EPA) National Risk Management Research Laboratory 

(NRMRL) in Research Triangle Park (RTP), North Carolina. Other APEX collaborators include the Federal 

1 
 
 

Aviation Administration (FAA), the U.S. Air Force’s Arnold Engineering Development Center (AEDC), 

California Air Resources Board, General Electric, Pratt & Whitney, Rolls-Royce, three commercial airlines, 

two international airports, the Missouri University of Science and Technology Center of Excellence 

(UMR), the University of California-Riverside, and Aerodyne Research, Inc. (ARI). 

The APEX program is a high visibility, major research priority for EPA’s Office of Transportation and Air 

Quality (OTAQ). The need for emission factors and source profiles has also been expressed by EPA 

Region 9 for use in air quality analyses around the Los Angeles International Airport. In addition, the 

program is also part of ongoing efforts by the Society of Automotive Engineers (SAE) E-31 Committee to 

develop a standard PM test method for aircraft engine certification as requested by ICAO. The APEX 

tests also support the FAA “Aircraft Emissions Characterization (AEC) Research Road Map” for 

commercial aircraft. 

1.2 Research Objectives 

The three sampling campaigns presented in this report (APEX-1, -2, and -3) focused on collecting the 

data necessary to update and improve emission factors (indices) and source profiles for commercial 

aircraft-generated PM. The specific objectives of this program were to: 

•	 Develop PM emission factors (indices) and chemical profiles for representative commercial aircraft 

engines (primary objective) and 

•	 Determine the effect of fuel properties (e.g., sulfur and aromatic content) and engine operating 

conditions (e.g., cold vs. warm) on the PM emissions (secondary objective). 

Measurements conducted by NRMRL during APEX-1, -2 and -3 were conducted in the plume, mostly at 

30 m behind the engine, and as such represent the total PM emissions present at that location. This 

testing was conducted using the Diesel Emissions Aerosol Laboratory (DEAL), and resulted in the first 

EPA-generated emission factors for commercial aircraft engines since the late 1970s. Samples extracted 

at other distances were analyzed by APEX collaborators. 

This program was originally designed to also provide critical PM emissions data for artificially diluted 

exhaust (measured 1 m behind the engine) as well as for the plume after natural atmospheric dilution and 

cooling. This comparison of methods was conducted during the first two tests of APEX-1 using the 

NRMRL Dilution Sampling System (DSS). However, because of the aggressive scope of the remainder of 

the project, limited availability of the DSS, and the disparate results produced between the two methods 

in APEX-1, this portion of the study was deferred for further investigation at a future date. 

1.3 Organization of this Report 

This report describes three related field campaigns for characterizing the PM emissions from engines 

manufactured by CFM International (CFMI), General Electric, Pratt & Whitney, and Rolls Royce under the 

auspices of the APEX program. Engines manufactured by CFMI were tested during all three field tests. 

The first campaign, APEX-1, was conducted in April 2004 at NASA’s Dryden Flight Research Center 

(DFRC) on Edwards Air Force Base (AFB), California. The second field campaign, APEX-2, was 

conducted in August 2005 at the Oakland International Airport in Oakland, California. The final campaign, 

APEX-3, was conducted in November 2005 at NASA’s Glenn Research Center at the Cleveland-Hopkins 

International Airport in Cleveland, Ohio. 

2 
 
Although the APEX research team conducted collaborative testing efforts, with the data being shared 

among the various project participants, this document addresses only the measurements conducted by 

EPA-NRMRL. The fuel flow rate at each power setting (i.e., percent rated thrust) was provided to NRMRL 

by APEX collaborators. Also, except for the carbon content of the fuels used in APEX-2, the chemical 

analysis of each fuel tested was also provided by others. Meteorological data were supplied by NASA for 

APEX-1 and The University of Central Florida (Volpe National Transportation Center) for APEX-3. Volpe 

also supplied background and ambient CO2 measurements during APEX-2 and -3. ARCADIS U.S., Inc. 

(ARCADIS) collected the weather data for APEX-2. 

Following this introduction, Section 2 describes the test sites and engine specifications for each of the 

three campaigns. The experimental apparatus and testing procedures are detailed in Sections 3 and 4, 

respectively. Section 5 details the post-test data analysis conducted. The test matrix, fuel composition 

and engine operation are discussed in Section 6, and the environmental and engine operating data are 

provided in Section 7. Sections 8 through 13 present, respectively, the data comparison of PM mass 

emissions, PM number emissions, particle size distribution (PSD) and geometric mean diameter (GMD), 

instrumental black carbon and particle surface-bound polycyclic aromatic hydrocarbon (PAH) emissions, 

gas-phase chemical composition, and PM-phase chemical composition. Each data section presents a 

comparison of results between the three campaigns, as well as selected comparisons to other available 

data collected by collaborators. A discussion of quality assurance (QA) is presented in Section 14, and 

the conclusions of this three-part sampling campaign are found in Section 15. Finally, all experimental 

data will be archived either on the NASA public website (http://particles.grc.nasa.gov) and/or a suitable 

EPA website to be established for this purpose. 

3 
 
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4 
 
2. Test Site Description and Engine Specifications 

2.1 APEX-1 Site Description and Setup 

The CFMI model CFM-56-2C1 jet engine, used throughout APEX-1, was mounted on a Boeing DC-8 

airframe at NASA’s DFRC, Edwards AFB, California. Figure 2-1 illustrates the experimental setup, located 

on PAD 14 at Edwards AFB. EPA extracted a sample from the centerline of the exhaust plume of the 

inside starboard engine at a distance of 30 m behind the engine exit plane. The location is indicated in the 

figure by the dot farthest from the engine with the label “3 sample rakes.” The dot closest to the engine 

represents a 1-m probe location, and the middle dot represents a 10-m probe location. Samples extracted 

from these locations were analyzed by other organizations collaborating on this research campaign. 

Figure 2-1. APEX-1 experimental setup. 

5 
 
Although spatially-integrated, multi-point sampling is normally preferred for most emissions 

measurements, based on the prior experience of APEX collaborators, the DEAL’s sample extraction 

system (described in detail in Section 3) was used to collect an air stream from a single point at the 

center line of the jet engine exhaust plume 30 m downstream from the engine exit. The concurrent 

measurement of CO2 at this measurement location allowed the normalization of the emissions to a fuelspecific basis using a carbon balance as described in Section 5. 

The sampling system was configured as a beveled nozzle connected to a 5-cm (2-in) outside diameter 

(OD) stainless steel tube that ran from the center of the plume (30 m behind the engine) to the inlet of the 

virtual impactor positioned in the DEAL trailer. The sample extraction system for the 30-m probe location 

consisted of the probe itself, two 90° turns (each fabricated from two 45° elbows), 18 m (60 ft) of straight 

tubing, and a Teflon “pop-off” valve for pressure relief at high engine power. The tubing entered the DEAL 

through the trailer floor and connected to the virtual impactor and the DEAL’s instrumented sampling 

tunnel. Thoroughly cleaned 5-cm (2-in) stainless steel tubing and uncontaminated fittings were used for 

the entire system, from the virtual impactor to the probe. The probe, shown in Figure 2-2, was constructed 

from 5-cm (2-in) diameter stainless steel tubing with a tapered inlet nozzle. The probe was attached to a 

tripod stand that was anchored to the tarmac. Three 6-m (20-ft) pieces of the 5-cm stainless steel tubing 

were used for the 18-m run from the probe to the trailer. 

Figure 2-2. DEAL 30-m exhaust plume probe assembly for APEX-1. 

A vertical slipjoint was fabricated to enable small height adjustments of the probe. A similar horizontal 

slipjoint (Figure 2-3) was located near the trailer to allow for small adjustments of the sample line length 

without having to relocate the trailer. Teflon gaskets and sanitary clamps were used to establish leak-tight 

joints at all connections (Kinsey et al., 2006a). The nozzle at the inlet of the assembly was positioned to 

face directly into the sample gas stream (i.e., the jet engine exhaust plume). The probe feet and the 

sections of tube closest to the probe were anchored to the tarmac and the remaining tube was either 

anchored or weighted down with sand bags. Based on the prior experience of APEX collaborators, no 

attempt was made to insulate the sampling line or otherwise condition the sample. 

6 
 
Figure 2-3. Sample line enters DEAL floor downstream of horizontal slipjoint and two 45° bends. 

Measurements were also made during APEX-1 using the dilution sampling system (DSS) which is 

described in Appendix A. However, the data obtained were generally inconsistent between the two tests 

conducted and with other APEX-1 data and, therefore, were deemed questionable and not included in 

any further analysis. The DSS was not used during APEX-2 or -3. 

2.2 APEX-2 Site Description and Setup 

During APEX-2, two CFMI model CFM56-7B24 jet engines were tested while mounted on a Boeing 737­

700 airframe, and CFM56-3B1 and -3B2 jet engines were tested while mounted on a Boeing 737-300 

airframe. Figure 2-4 illustrates the experimental setup, which was located inside a three-sided noise 

abatement enclosure, known as a ground run-up enclosure (GRE), at the Oakland International Airport in 

Oakland, California. As was done during APEX-1, EPA extracted a sample from the exhaust plume of the 

starboard engine at a distance of 30 m behind the engine exit plane. Additional probes were located at 

distances of 1 and 54 m behind the starboard engine. Samples extracted from these locations were 

analyzed by other APEX collaborators. 

A plume sampling system was used to collect an air sample from the jet engine exhaust for subsequent 

analysis using instrumentation located in the DEAL trailer. The plume sampling system was composed of 

a probe located at the exhaust centerline 30 m behind the starboard engine. The probe was connected to 

the inlet of the virtual impactor in the DEAL by a 5-cm (2-in) OD stainless steel sampling line. The 

configuration of the plume sample extraction system for the 30-m probe was exactly the same 

configuration used during APEX-1, with one exception. The system consisted of the probe and two 90° 

turns (each fabricated from two 45° elbows), but there was an additional 3 m of sample line length (21 m 

total). This tubing entered the DEAL through the trailer floor, after which the tubing connected to the 

virtual impactor and the DEAL’s instrumented sampling tunnel. Clean 5-cm stainless steel tubing and 

uncontaminated fittings were again used for the entire system from the virtual impactor to the probe. 

Again, the line was not insulated. 

7 
 
Figure 2-4. APEX-2 experimental setup. 

The 30-m probe stand used during APEX-2 is shown in Figure 2-5. The cone-shaped High-Efficiency 

Particulate Air (HEPA) filter fitted on the probe nozzle inlet was used in a pre-test particle leak check. An 

array of nine T-type thermocouples and a pitot tube mounted on the probe stand provided additional 

information on the structure of the plume during testing. The pitot tube and associated differential 

pressure cell is shown in Figure 2-5 mounted directly under the probe inlet. The thermocouple array 

consisted of five thermocouples mounted on the vertical member and four mounted on the horizontal 

member. Also shown in Figure 2-5 is the vertical slipjoint used during both APEX-1 and APEX-2 that 

allowed small height adjustments of the probe. The associated mounting apparatus and most of the 

sampling line were hard-mounted to the tarmac of the GRE using a series of drilled anchors and bolts. 

Outside the jet exhaust, the sampling line was secured with sand bags. 

8 
 
Figure 2-5. DEAL 30-meter exhaust plume probe assembly for APEX-2. 

Note: the sandbags in the photo were later replaced with anchors and bolts drilled into the tarmac up to 

the point that the sample line was outside the jet exhaust. 

2.3 APEX-3 Site Description and Setup 

During APEX-3, two CFMI model CFM56-3B1 engines, tested during APEX-2 on a Boeing 737-300 

airframe, were tested again. In addition, five other jet engines of various sizes were studied. These 

engines included the following: 

• General Electric CJ610-8ATJ turbojet on a Lear Model 25 airframe 

• Rolls Royce AE3007A1E and AE3007A1/1 turbofans on Embraer ERJ-145 airframes 

• Pratt and Whitney PW4158 turbofan on an Airbus A300 airframe 

• Rolls Royce RB211-535E4-B turbofan on a Boeing 757 airframe. 

Figure 2-6 illustrates the experimental setup at NASA’s Glenn Research Center at the Cleveland-Hopkins 

International Airport. The aircraft engine test pad was located on the eastern extension of the airport and 

across the street from the NASA aircraft hangar. A chain link fence serves as a boundary between the 

airport property and the road to the west of the pad; the fence then continues between the airport property 

and the UPS distribution center and their parking lot. 

9 
 
Figure 2-6. APEX-3 experimental setup. 

In APEX-3, EPA extracted a sample from the engine exhaust plume at a distance of 30 m behind the exit 

plane. In addition, samples were sometimes collected from either a 15-m or 43-m probe location 

depending on aircraft type. An additional probe was located 1 m behind the engine. Samples extracted 

from this location were analyzed by other organizations collaborating on this research campaign. 

A plume sampling system was used to collect an air sample from the jet engine exhaust for subsequent 

sampling and analysis using instrumentation located in the DEAL trailer. The plume sampling system was 

composed of three probes located at the plume centerline 15 m, 30 m, and 43 m behind the starboard 

engine. In all three locations, the probe tip was a 5-cm stainless steel tube with a tapered end, identical to 

the probe tips used in APEX-1 (Figure 2-2) and APEX-2 (Figure 2-5). 

For the APEX-3 campaign, new probe stands were specially designed for the 15-, 30-, and 43-m 

sampling locations. The new designs were required so that the probe tip with a large T-type thermocouple 

array and pitot tubes could be positioned at different heights to accommodate the various aircraft being 

10
 

 

43    m Probe

studied. During the first test, the probe stands were observed to be unstable and all three stands had to 

be removed from the test pad. Therefore, the probe stands from APEX-1 and APEX-2 were used for the 

30-m location, and a second stand was fabricated from parts on-hand at the NASA Glenn machine shop. 

This stand was alternated between the 15- and 43-m sampling locations. The replacement probe stands 

were positioned on the pad and secured with anchors, allowing the testing campaign to continue. 

However, the replacement stands did not have the ability to raise the probe tips to always be in the center 

of the exhaust plume of some of the engines tested, nor could they accommodate the thermocouples and 

pitot tubes that were to be used to collect additional information on the structure of the plume. Like 

APEX-1 and -2, uninsulated, 5-cm diameter stainless steel sampling lines ran from the probe to the 

DEAL. 

Since more than one sampling point was used during certain tests, a special valving system was 

developed specifically for APEX-3. This system allowed sample to flow to the DEAL as well as the NASA 

trailer on an as-needed basis. Figure 2-7 illustrates the valve system used for the three sampling points 

during APEX-3. The layout of the sample lines was previously shown in Figure 2-6. End-of–runway 

sampling of advected (wind transported) aircraft plumes was also attempted during APEX-3, but later 

abandoned due to poor wind conditions. The DEAL’s “wing” probe used to extract these samples is 

shown in Figure 2-8. 

Figure 2-7. Valve arrangement used for multi-point sampling during APEX-3. 

11
 

Figure 2-8. DEAL’s “wing probe”. 

2.4 Engines Tested 

A single engine was tested during APEX-1: a CFMI model CFM-56-2C1 mounted on a NASA-owned 

Boeing (formerly McDonnell-Douglas) DC-8 jet aircraft (Figure 2-9). The engines were originally installed 

in 1986 but had recently been rebuilt. The aircraft was located at NASA’s DFRC on Edwards AFB, 

California. During APEX-2, three engine dash numbers of the same CFMI engine model were tested: 

CFM56-3B1, CFM56-3B2 and CFM56-7B24. These engines were mounted on a Boeing 737-300 (-3B1 

and -3B2) and a Boeing 737-700 (-7B24) airframe, respectively. The aircraft were owned and operated by 

Southwest Airlines at Oakland International Airport, Oakland, California. During APEX-3, testing of the 

CFMI CFM56 family of engines continued. Two of the eleven tests were conducted with a model CFM56­

3B1, which had been tested during APEX-2. 

Figure 2-10 shows the CFM56 engines tested during the three field campaigns. This family of engines 

includes four fan sizes and thrusts ranging from 18,500 to 34,000 pounds, with applications in short-, 

medium- and long-range aircraft. The CFM-56-2 model engine first entered commercial service in 1982 

on the DC-8 airframe. The CFM-56-2 engine is the predecessor of the CFM-56-3 model, which was 

introduced into commercial service in 1984 and which retained the core and the low pressure turbine of 

the earlier model. The CFM-56-7 engine was introduced into commercial service in 1997. The CFM-56 

family is one of the most widely used engines in the commercial fleet. 

During APEX-3, engines from three additional manufacturers were tested: General Electric, Pratt & 

Whitney, and Rolls Royce. Table 2-1 details the engines tested during the three campaigns. 

12
 
13
 


Figure 2-9. CFMI Model CFM56-2C1 jet engine tested during APEX-1. 

Figure 2-10. CFMI Model CFM56 engines: CFM56-2 (left), CFM56-3 (center), and CFM56-7 (right). 
 

 

 

Rated ICAO Smoke Numberc 

Bypass Tail Enginea Airframe Thrustb Test Site/Test # Ratiob Number (kN) T/O C/O App Idle 

Boeing CFMI CFM56-2C1 6 97.86 6.0 3.0 2.6 2.2 N817NA APEX-1 / All Tests DC-8 

Boeing N435WN; CFMI CFM56-7B24 5.2 107.7 12.6d NA NA NA APEX-2 / Test # 1 & 4 737-700 N429WN 

N353SW; Boeing APEX-2 / Test # 2; CFMI CFM56-3B1 5.1 89.41 4.0 2.5 2.5 2.2 N14324; 737-300 APEX-3 / Test # 1 & 11 N70330 

Boeing CFMI CFM56-3B2 5.1 98.3 6.0 3.0 2.5 2.2 N695SW APEX-2 / Test # 3 737-300 

c CJ610

8ATJ (Turbojet) Starboard Model 25 

Embraer 

General Electri ­ Lear na 13.12 NA NA NA NA — APEX-3 / Test # 2 & 5 

Rolls Royce AE3007A1Ee 4.8 33.7 1.0 0 0 0 N11193 APEX-3 / Test # 3 (Starboard) 

ERJ145 & 4 (Port) 

Pratt & Whitney 4158 

Starboard 

Rolls Royce RB211­

535E4-B Starboarde 

Rolls Royce RB211­

535E4-B Starboarde 

Rolls Royce AE3007A1/1 

Starboarde 

Airbus 

A300 4.6 258.0 8.1d NA NA NA N729FD APEX-3 / Test # 6 & Test #7 

Boeing 

757-324 4.1 191.7 7.3d NA NA NA N75853 APEX-3 / Test # 8 

Boeing 

757-324 4.1 191.7 7.3d NA NA NA N74856 APEX-3 / Test # 9 

Embraer 

ERJ145 4.8 34.74 1.0 0 0 0 N16927 APEX-3 / Test # 10 

Table 2-1. Engines Tested in APEX-1, -2 and -3 

 

a. All engines are turbofan except as noted. 

b. Civil Turbojet/Turbofan Specifications http://www.jet-engine.net/civtfspec.html or ICAO Databank Issue 15-C. 

c. Data from ICAO Engine Emissions Databank Issue 15-C. 

T/O = take-off 

C/O = climb-out

 App = approach 

NA = not available 

d. Maximum SN; no power specified. 

e. These engines are internally mixed-flow turbofan engines. 

14
 

 

3. Experimental Apparatus 

3.1 General Description 

The DEAL consists of a Kenworth T-800 diesel-powered tractor and a 45-ft Great Dane trailer. General 

specifications of the DEAL are outlined in Table 3-1. A detailed description of the construction and 

operation of the DEAL and the various instruments may be found in the approved quality assurance 

project plan (QAPP) for each of the three studies (EPA, 2004; EPA, 2005a; EPA, 2005b). 

Table 3-1. Specifications of the DEAL 

Vehicle Parameter Specification 

SAE Vehicle Classification 3-S2 

Gross Vehicle Weight (GVW) Classification 8 

Service Classification D 

Gross Train Weight or GVW 36,284 kg (80,000 lb) 

Tractor Wheelbase 6.1 m (20 ft) 

Length of Trailer 14 m (45 ft) 

Tire Size/Type Michelin 11R24.5 radial 

Engine 2000 Detroit Diesel Series 60 

Engine Displacement 12.7 L 

Engine Power Output 373 kW (500 hp) @ 2100 rpm 

Engine Emission Limit 

(Measured at West Virginia University) 0.13 g/kW·hr (0.1 g/bhp·hr) 

Electric power is supplied to the trailer through two panel boxes from which individual circuits are run to 

various locations inside the trailer to support the power requirements of all the instruments, pumps, 

blowers and other equipment. The panel boxes can receive power from a conventional power source or 

from two 12-kW diesel-powered generators mounted to the underside of the trailer. When the DEAL is in 

its staging configuration, it can accept external (i.e., utility) power and additional calibration gases can be 

connected to the Continuous Emission Monitoring System. All instruments are supplied conditioned 

power via an uninterruptible power supply (UPS). Pumps and other equipment that do not contain 

delicate electronics do not receive conditioned power from the UPS. 

For APEX-2 and -3, a rental tractor was used instead of EPA’s Kenworth T-800 tractor to pull the DEAL 

trailer to the test site. Because the main computer operator’s station used to monitor and control the 

sampling instruments and equipment was located in the Kenworth sleeper, a new desktop computer 

15
 

station was set up inside the DEAL trailer. To simplify the electrical setup for the DEAL and the other 

participants during APEX-2 and -3, a single power station was designed and fabricated to make the 

electrical setup and tear-down more efficient for the entire research team. The electrical power skid is 

shown in Figure 3-1. 

Figure 3-1. Electrical power skid used during APEX-2 and APEX-3. 

3.2 Sampling System 

The DEAL uses two centrifugal blowers, each controlled by a variable frequency drive and mass flow 

meter, to continuously extract 1.1 actual m3

/min — 40 actual ft3/min (acfm) — of sample gas from the 

plume. After extraction, the plume sample flows through a 5-cm diameter stainless steel sampling tube 

into a PM-2.5 “cut point” (i.e., particle diameter representing a 50% collection efficiency for equivalent unit 

density spheres ≤2.5 μm in diameter) virtual impactor, and then into an 8.8-m long, 15-cm inside diameter 

(ID) stainless steel sampling tunnel. A series of “buttonhook” sampling nozzles, which are staggered in 

height inside the tunnel to minimize aerodynamic interference, is used to extract samples from the tunnel. 

The sample flow captured by each nozzle exits the plume tunnel through flow splitters that direct the flow 

from the sampling tunnel to various instruments. The tunnel is supported from the trailer floor by columns 

integrated into the plume instrument rack. Conductive silicone rubber lines connect the instruments to the 

appropriate sample splitter. 

The DEAL was outfitted and configured to accommodate the sample collection and continuous monitoring 

requirements of the APEX monitoring plan. Figure 3-2 is representative of the DEAL exhaust plume 

measurement equipment configuration used for speciated testing during the APEX campaigns. In this 

context, “speciated” refers to those tests designated for the determination of gas- and particle-phase 

chemical characteristics by time-integrated sampling. 

16
 
17 

Figure 3-2. Representative DEAL exhaust plume measurement equipment configuration, speciated test.
During the three measurement campaigns, the plume sampling instrument configuration varied slightly 

from that shown in Figure 3-2. For APEX-1, the configuration shown changed only in that there were two 

instrument substitutions. On splitter 2, a tracer gas analyzer (B&K Model 1302 Photoacoustic Analyzer) 

was used to measure CO2 instead of the continuous online Milton Roy Model 5300A analyzer. On splitter 

3, the TSI Model 3936 (Long DMA—Differential Mobility Analyzer) Scanning Mobility Particle Sizer 

(SMPS) was substituted for the TSI Model 3090 Engine Exhaust Particle Sizer (EEPS). Note also that 

during APEX-1, the Quartz Crystal Microbalance (QCM) failed to function properly. Therefore, no data 

were recorded from this instrument during APEX-1. 

The background was sampled by an independent sample extraction and analysis system. The 

background sample air enters the system through a “rain hat” to an elevated transfer line. The sample 

stream is then routed into two parallel PM-10/PM-2.5 (particles ≤10 μm or ≤2.5 μm in aerodynamic 

diameter, respectively) pre-collectors and into a sampling tunnel from which the instruments draw their 

sample through staggered probes and flow splitters. Figure 3-3 is representative of the DEAL background 

measurement equipment configured for speciated testing during the APEX campaigns. 

During APEX-1, the configuration shown in Figure 3-3 changed only because there were two instrument 

substitutions. On splitter 1, an integrated bag sampler was used instead of the Milton Roy Model 5300A 

CO2 analyzer, and the older 3934 SMPS was used instead of the 3936 (Long DMA) SMPS. 

For non-speciated tests, whether for plume or background sampling, there again were only minor 

differences in the DEAL configuration. First, no sampling was conducted off splitter 1: the SUMMA 

canister and the 2,4-dinitrophenylhydrazine (DNPH) and potassium iodide (KI)-DNPH cartridges were 

removed. Second, during APEX-1, the dual series of polyurethane foam (PUF) cartridges was replaced 

with two quartz filters for both plume and background sampling. Third, during APEX-3, no sample 

collection media were run during the non-speciated tests. 

In APEX-1, three of the nine tests were speciated. During APEX-2, all sampling equipment configurations 

in the DEAL were for speciated tests. Finally, six of the eleven tests conducted during APEX-3 were also 

speciated. Recall that the end-of-runway sampling in APEX-3 was unsuccessful due to poor wind 

conditions. 

Tables 3-2 and 3-3 present detailed information about the sampling location of each instrument inside the 

DEAL for the plume and background sample tunnels, respectively, for all three APEX sampling 

campaigns. Any instrument substitutions or the removal of any instruments between campaigns has been 

reflected in this table. Note that Tables 3-2 and 3-3 also distinguish between tests in which samples were 

collected for speciation and tests in which no samples were collected for speciation. Table 3-4 presents 

descriptions of the measurement capabilities of the DEAL and is followed by descriptions of each 

individual instrument. 

18
 

19 

Figure 3-3. Representative DEAL background measurement equipment configuration, speciated test.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3-2. Measurement Configuration for the Plume Sample Tunnel 

Campaign Splitter 1 Splitter 2 Splitter 3 Splitter 4 

APEX Test # DNPH SUMMA CO2 

PAS 

2000 QCM 1105a TEOM CPC Aethalometer 

3936L 

SMPS EEPS Nano SMPS 

Thermal 

Denuder ELPI Teflon + 2Q 

Quartz 

+ PUF 

1 EPA-1 X X PA X X X X X X X X X X 

EPA-2 X X PA X X X X X X X X X X 

NASA-1 PA X X X X X X X X 2Q 

NASA-1a PA X X X X X X X X 2Q 

EPA-3 X X PA X X X X X X X X X X 

NASA-2 

NASA-3 

PA X X 

PA X X 

X X X X 

X X X X C 

X 

C C2Q X 

NASA-4 

NASA-5 

PA X X 

PA X X 

X X X X 

X X X X C 

X 

C C2Q X 

2 T1 

T2 

T3 

T4 

X X 

C 

X 

X 

X X 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

C 

X 

C C X 

X X X X 

3 T1 X X X X X X X X X 

T2 X X X X X X X X X 

T3 

T4 

X X 

X X 

X X X X 

X X X X 

X X X X 

X X X X 

C 

X 

C C

X 

T5 X X X X X X X X X 

T6 

T7 

C 

X 

X 

X X X X 

X X X X 

X X X X 

X X X X 

C 

X 

C C

X 

T8 

T9 X X 

X X X X 

X X X X 

X X X X 

X X X X 

C 

X 

X X X 

T10 X X X X X X X X X 

T11 X X X X X X X X X X X X X X 

2Q = Double quartz backup filters (NASA runs) PUF = Polyurethane foam 

CPC = Condensation Particle Counter QCM = Quartz Crystal Microbalance 

DNPH = 2,4-Dinitrophenylhydrazine SMPS = Scanning Mobility Particle Sizer 

EEPS = Engine Exhaust Particle Sizer SUMMA = SUMMA-polished stainless steel canisters 

ELPI = Electrical Low Pressure Impactor TEOM = Tapered Element Oscillating Microbalance 

PA = Photoacoustic analyzer 

C = Cartridges were composited for both runs to collect sufficient sample mass (see Section 6) 

20
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3-3. Measurement Configuration for the Background Sample Tunnel 

Campaign Splitter 1 Splitter2 Splitter 3 

APEX Test # CPC 1400 

TEOM 

3934 

SMPS 

3936L 

SMPS 

Bag 

Samp. CO2 

Teflon 

+2Q 

Quartz 

+ PUF ELPI SUMMA DNPH 

1 EPA-1 X X X X X X X X X 

EPA-2 X X X X X X X X X 

NASA-1 X X X X X 2Q X 

NASA-1a X X X X X 2Q X 

EPA-3 X X X X X X X X X 

NASA-2 

NASA-3 

X X X X 

X X X X C* C2Q 

X 

X 

NASA-4 

NASA-5 

X X X X 

X X X X C C2Q 

X 

X 

2 T1 

T2 

T3

 T4 

X X X X 

X X X X 

X X X X 

X X X X 

X X X X 

C C X X 

X X 

X X X X 

X 

C 

X 

3 T1 X X X X X 

T2 X X X X X 

T3 

T4

 X X X X 

X X X X 

C C 

X X 

X X 

X 

X 

T5 X X X X X 

T6 

T7

 X X X X 

X X X X 

C C 

X X 

X X 

C 

T8 X X X X X 

T9 X X X X X X X X X 

T10 X X X X X 

T11 X X X X X X X X X 

2Q = Double quartz backup filters (NASA runs) PUF = Polyurethane foam 

CPC = Condensation Particle Counter QCM = Quartz Crystal Microbalance 

DNPH = 2,4-Dinitrophenylhydrazine SMPS = Scanning Mobility Particle Sizer 

EEPS = Engine Exhaust Particle Sizer SUMMA = SUMMA-polished stainless steel canisters 

ELPI = Electrical Low Pressure Impactor TEOM = Tapered Element Oscillating Microbalance 

PA = Photoacoustic analyzer * = Teflon filter was not composited 

C = Cartridges were composited for both runs to collect sufficient sample mass (see Section 6) 

21
 

Parameter Sampling 

Location 

Measurement Technique Type of Sample Instruments and Sampling Media 

PM-2.5 mass concentration Background 

Background Plume Plume Plume 

Microbalance 

Gravimetric analysis 

Microbalance 

APEX-2 & -3: QCM 

Gravimetric analysis 

Continuous 

Time-integrated 

Continuous 

Continuous 

Time-integrated 

Rupprecht and Patashnick Series 1

47-mm Teflon filter with double qua

phase “blow off” a 

Rupprecht and Patashnick (now Th

SEMTECH Model RPM-100 particu

47-mm Teflon filter with double qua

Particle size distribution Background 

Background 	 

Low pressure cascade impactor (aerodynamic 

diameter) Electrical mobility classifier/condensation nuclei counter (electrical mobility diameter) 

Continuous / time-integrated Continuous 

Dekati ELPI APEX-1: TSI Model 3934 SMPS, MCPC APEX-2 & -3: TSI Model 3936 SMPModel 3025a CPC, Model 3081 DM

Plume Plume Plume 

Low-pressure cascade impactor (aerodynamic 

diameter) 

Electr cal mobility ci lassifier/condensation nuclei 

counter (electrical mobility counter) 

APEX-1: electrical mobility classifier/condensation 

nuclei counter (electrical mobility counter) APEX-2 & -3: electrical mobility classifier/electrometers (electrical mobility counter) 

Continuous /  time-integrated 

Continuous 

Continuous 

Dekati ELPI TSI Model 3936 SMPS (Nano). MoCPC, Model 3085 DMA 

APEX-1: TSI Model 3936 SMPS (lo

3025 CPC, Model 3081 DMA APEX-2 & -3: TSI Model 3090 EEP

PM-2.5 number concentrationc Background 

Plume 

Condensation nuclei counter 

Condensation nuclei counter 

Continuous 

Continuous 

Model 3025a CPC 

Model 3025a CPC + diluter 

Elemental(EC/OC) 

 carbon/organic carbon Background 

Plume 

Plume 

Thermo-optical analysis (NIOSH Method 5040) 

Thermo-optical analysis (NIOSH Method 5040) 

Optical attenuation/UV absorption (black carbon) 

Time-integrated 

Time-integrated 

Continuous 

Prefired 47 mm quartz filter 

Prefired 47 mm quartz filter 

TSI 3302a Diluter +Magee Model A

PM semivolatile organic compounds (SVOCs) 

Background 

Background 

Plume Plume Plume 

GC/MS 

Low-pressure cascade impactor 

GC/MS Low-pressure cascade impactor 

UV analyzer (particle surface PAHs) 

Time-integrated 

Time-integrated 

Time-integrated 

Time-integrated 

Continuous 

Prefired 47 mm quartz filter with 4 P

12 aluminum foil ELPI stages + pre

Prefired 47 mm quartz filter with 4 P

12 aluminum foil ELPI stages + pre

EcoChem Model PAS 2000 

Table 3-4. Measurements Performed by the DEAL during APEX-1, -2, and -3 

22
 

23
 


Parameter Sampling 

Location 

Measurement Technique Type of Sample Instruments and Sampling Media 

PM volatile compounds (VOCs) Plume Gravimetric/thermo-optical analysis Time-integrated Dekati Model EKA-111 thermal den

prefired quartz filters 

PM inorganic water-soluble ions Background Ion chromatography Time-integrated Teflon filter 

Plume Ion chromatography Time-integrated Teflon filter 

PM elemental composition Background XRF Time-integrated Teflon filter

 Plume XRF Time-integrated Teflon filter APEX-1 CO, CO2, total VOCs Background IR absorption Integrated bage Brüel & Kjær Model 1302 Photoaco

Plume IR absorption Continuous Brüel & Kjær Model 1302 Photoaco

APEX-2 & -3 CO2 Background IR absorption Continuous Milton-Roy (CA Analytical) Model 5

Plume IR absorption Continuous Milton-Roy (CA Analytical) Model 5

Gas-phase NMOCs Background GC/MS/FID Time-integrated SUMMA-passivated canister Plume GC/MS/FID Time-integrated SUMMA-passivated canister 

Gas-phase carbonyl compounds Background HPLC Time-integrated DNPH impregnated silica gel cartrid

Plume HPLC Time-integrated DNPH impregnated silica gel cartrid

Sample temperaturef Plume tunnel Thermocouple Continuous K-Type thermocouples; T-Type onl

APEX-2 plume temperature Plume Thermocouples Continuous Multiple T-type thermocouples 

APEX-2 plume velocity Plume Pitot tube Continuous Standard pitot tube plus differential 

APEX-2 wind speed/direction Background Propeller anemometer & wind vane Continuous Vaisala MAWS weather station 

a Filter holder design per Federal Test Procedure (FTP) published in 40 Code of Federal Regulations (CFR), Part 86. “Blow off” are gas-phase semivolatile species that have b

deposited on the primary filter by the air flow passing through the medium. 

b Aluminum foil substrates from the ELPI were not analyzed due to insufficient mass. c These measurements were redundant and these data were not used. d The aethalometer measures “black” carbon which approximates elemental carbon content as determined from diesel engine testing at West Virginia University (Kinsey et al.e Post-test analysis of time-integrated Tedlar bag sample collected over the entire test period. f Temperature was not monitored in sampling lines. 

CPC = Condensation Particle Counter NMOC = Nonmethane Organic Compound 

DMA = Differential Mobility Analyzer NIOSH = National Institute for Occupational Safety and Health DNPH = 2,4-Dinitrophenylhydrazine PAH = Polycyclic Aromatic Hydrocarbon EEPS = Engine Exhaust Particle Sizer PUF = Polyurethane Foam ELPI = Electrical Low Pressure Impactor QCM = Quartz Crystal Microbalance FID = Flame Ionization Detector SMPS = Scanning Mobility Particle Sizer GC/MS = Gas Chromatography/ Mass Spectrometry TEOM = Tapered Element Oscillating Microbalance HPLC = High Performance Liquid Chromatography UV = Untraviolet IR = Infrared XRF = X-ray Fluorescence 
In addition to the above equipment, exit plane sampling was also attempted at a location of 1 m during 

APEX-1 using EPA’s Dilution Sampling System (DSS). This system is based on the dilution stack sampler 

developed by Hildeman et al. (1991) and described in Appendix A. As stated previously, no useful data 

were obtained from the DSS and thus the measurement results are not presented in this report. 

3.3 Instrumentation 

3.3.1 Tapered Element Oscillating Microbalance Monitors 

The Rupprecht and Patashnick (R&P) Tapered Element Oscillating Microbalance (TEOM) Series 1105 

Diesel Particulate Monitor and Series 1400a Ambient Particulate Monitor incorporates a patented inertial 

balance that directly measures the mass collected on an exchangeable filter cartridge. The TEOM 

monitors the change in the natural oscillating frequency of a tapered element as additional mass collects 

on the filter. The sample flow passes through the filter, where PM collects, and then continues through the 

hollow tapered element on its way to a dynamic flow control system and vacuum pump. 

The TEOM mass transducer does not normally require recalibration because it is specially designed and 

constructed from non-fatiguing materials. The mass calibration of the TEOM was verified before sampling 

using an optional Mass Calibration Verification Kit that contains a filter of known mass. A flow controller 

maintains the sample flow rate input by the user. TEOM Series 1105 interfaces with the multicomputer via 

an input/output (I/O) card, cable, and software supplied by the manufacturer, Thermo Electron, Inc. The 

TEOM Series 1400a monitor incorporates the same technology as the 1105a, but incorporates an internal 

microprocessor and data storage system. 

3.3.2 Quartz Crystal Microbalance 

An older instrument, which has recently been reintroduced, is the QCM. The harmonic oscillator principle 

used in the QCM is similar to the TEOM, except that the collected PM is actually deposited onto a crystal 

element using an electrostatic precipitator (ESP). Due to its high-frequency operation, the QCM exhibits 

far less instrumental noise than the TEOM, but the QCM also can overload in a relatively short period. To 

offset this problem, a dilutor was used with the instrument to extend the useful life of the crystal element. 

The QCM was operated and the data collected using the software provided by the manufacturer. 

3.3.3 Electrical Low Pressure Impactor 

The Dekati Electrical Low Pressure Impactor (ELPI) is a real-time particle size spectrometer designed for 

real-time monitoring of aerosol particle size distribution. The ELPI measures airborne particle size 

distributions (PSD) with 12 channels in the size range of 0.03 to 10 μm. The principle is based on 

charging, inertial classification, and electrical detection of the aerosol particles. The instrument consists 

primarily of a corona charger, low pressure cascade impactor, and multi-channel electrometer. The ELPI 

communicates with the multicomputer via a serial port using the ELPI VI software provided with the 

instrument. The software is used for setup and configuration and to view data. 

3.3.4 Engine Exhaust Particle Sizer 

The TSI Model 3090 EEPS measures the size distribution and number concentration of exhaust particle 

emissions in the range from 5.6 to 560 nm. The instrument continuously draws a sample of the exhaust 

flow into the inlet, and the particles in the flow are positively charged to a predictable level using a corona 

charger. These charged particles are then introduced to the measurement region near the top-center of a 

high-voltage electrode column surrounded by a stack of electrometers and the particles are transported 

24
 

 

 

 

down the column in a sheath of HEPA-filtered air. A positive voltage is applied to the electrode and 

creates an electric field that repels the positively charged particles outward according to their electrical 

mobility. 

Charged particles strike the respective electrometers and transfer their charge. A particle with higher 

electrical mobility strikes an electrometer near the top, whereas a particle with lower electrical mobility 

strikes an electrometer lower in the stack. This multiple detector arrangement using highly sensitive 

electrometers allows for simultaneous concentration measurements of multiple particle sizes. 

3.3.5 Scanning Mobility Particle Sizer 

The TSI Model 3934 SMPS is a system that measures the size distribution of aerosols in the size range 

from 10 to 1,000 nm. The particles are classified with the Model 3071A Electrostatic Classifier and their 

concentration is measured with the Model 3010 Condensation Particle Counter (CPC). The system 

communicates with the multicomputer via a serial port. The Aerosol Instrument Manager (AIM) software 

Version 5.2 is used for setup and configuration and to view data. 

The TSI Model 3936 Long SMPS is a system that measures the size distribution of aerosols in the size 

range from approximately 9 nm to 1,000 nm. The particles are classified with the Model 3080 Electrostatic 

Classifier with a Model 3081 Long DMA, and their concentration is then measured with the Model 3025A 

CPC. The Long DMA is the traditional length DMA used in the older Model 3071 Electrostatic Classifier. 

The system communicates with the multicomputer via a serial port. 

The TSI Model 3936 Nano-SMPS is a system that measures the size distribution of aerosols in the size 

range from 2 to 150 nm. The particles are classified with the Model 3080 Electrostatic Classifier with a 

Model 3085 Nano-DMA and their concentration is then measured with the Model 3025A CPC. The NanoDMA is optimized for the size range below 20 nm. The system communicates with the multicomputer via 

a serial port. The AIM software Version 5.2 package is used for setup and configuration, and to view data. 

3.3.6 Condensation Particle Counter 

The Model 3025A CPC detects and counts particles larger than 3 nm in diameter by an optical detector 

after a supersaturated vapor (n-butyl alcohol) condenses onto the particles, causing them to grow into 

larger droplets. The range of particle concentrations extends from less than 0.01 to 9.99 × 104 

particles/cm3

. The system communicates with the multicomputer via a serial port. The CPC LOG software 

developed by NRMRL was used to log the data. 

3.3.7 Aethalometer 

The Magee (Andersen) Model AE-2 Aethalometer measures real-time “black” carbon [i.e., elemental 

carbon (EC)] and is designed for fully automatic and unattended operation. The sample is collected as a 

spot on a roll of quartz fiber tape. An optical method is then used to measure the attenuation of a beam of 

light transmitted through the sample. The optical attenuation is linearly proportional to the amount of black 

carbon collected on the quartz fiber tape. The aethalometer communicates with the multicomputer via an 

analog output signal with a voltage range of 0 to 5 volts. Operation of the instrument was checked before 

sampling using an optical test strip. 

25
 

 

3.3.8 Photoelectric Aerosol Sensor 

The PAS 2000 Photoelectric Aerosol Sensor works on the principle of photoionization of particle surfacebound polycyclic aromatic hydrocarbons (PAH). Using an Excimer lamp, the aerosol flow is exposed to 

ultraviolet (UV) radiation. The Excimer lamp offers a high intensity, narrow band source of UV radiation. 

The wavelength of the light is chosen so that only the PAH-coated aerosols are ionized, while gas 

molecules and non-carbon aerosols remain neutral. The aerosol particles that have PAH molecules 

adsorbed on the surface emit electrons, which are subsequently removed when an electric field is 

applied. The remaining positively-charged particles are collected on a filter inside an electrometer, where 

the charge is measured. The resulting electric current establishes a signal that is proportional to the 

concentration of total particle-bound PAHs. 

3.3.9 Tracer Gas Analyzer 

The Brüel and Kjær (B&K) Model 1302 Photoacoustic Analyzer operates on the principle of infrared (IR) 

photoacoustic spectroscopy. A pump draws air from the sampling point through two air filters to flush out 

the "old" air in the measurement system and replace it with a "new" air sample, which is hermetically 

sealed in the analysis cell by closing the inlet and outlet valves. Light from an IR source is reflected off a 

mirror, passed through a mechanical chopper (which pulsates it), and then through one of the optical 

filters in a filter carousel. The light transmitted by the optical filter is selectively absorbed by the gas being 

monitored, causing the temperature of the gas to increase. Because the light is pulsating, the gas 

temperature increases and decreases causing an equivalent increase and decrease in the pressure of 

the gas (an acoustic signal) in the closed cell. Two microphones mounted in the cell wall measure this 

acoustic signal, which is directly proportional to the concentration of the monitored gas present in the cell. 

During APEX-1, the photoacoustic analyzer was used to sample from two different sources. During 

testing, the analyzer recorded the results of a continuous sample of the jet engine exhaust from the plume 

tunnel. After the test was completed, the same instrument was used to analyze an integrated bag sample 

captured from the background tunnel during the test. Whether sampling from the plume tunnel or the bag 

sampler, the same bypass flow configuration and equipment was used to allow the instrument’s internal 

pump to draw its own sample from a slipstream. The bypass flow system consisted of a rotameter, an 

external pump to overcome the negative pressure in the plume tunnel, a three-way valve to switch 

between the calibration line and the sample line, and a second three-way valve to switch between the bag 

sampler line and the plume tunnel sample line. Under all operating scenarios, the gas being introduced to 

the analyzer flowed through the external pump and the rotameter. 

3.3.10 Thermal Denuder 

The Dekati Model EKA-111 Thermodenuder is designed to remove volatile and semivolatile compounds 

from an exhaust sample. These compounds are known to cause variations in particle measurements 

through nucleation and condensation. The Thermodenuder heats the sample gas up to 250 °C and 

therefore vaporizes the unwanted compounds. The vaporized compounds are subsequently collected in 

active charcoal in the adsorber section. Since the particles in the sample have much slower diffusion 

speeds (less than 1/100 for 10 nm particles) than the vaporized compounds, the vaporized volatiles are 

collected efficiently, while the sample aerosol particles follow the gas stream lines unaffected. Chilled 

water driven through the cooling channels cools the sample aerosol in the adsorber. 

26
 

3.3.11 Carbon Dioxide Analyzer 

The Milton-Roy (CA Analytical) Model 5300A analyzer uses a technique based on the IR absorption 

characteristics of gases to measure gas concentration. A single beam of IR energy is modulated and 

passed through a sample cell containing the gas to be measured. The beam emerges attenuated by the 

amount of energy absorbed by the gas in the sample. Changes in the concentration of the gas result in 

changes in the intensity of the beam. The remaining energy in the beam is passed serially through two 

cavities of an IR detector, which is a mass-flow sensor filled with gas of the type to be measured. 

Changes in the intensity of the beam change the pressure differential between the cavities and, 

consequently, the balance of an electrical bridge in the detector circuit. Electronic processing of the 

imbalance signal is used to generate an electrical output signal proportional to the concentration of the 

gas measured. 

3.4 Data Acquisition System 

The data acquisition system (DAS) used in the DEAL consists of a multicomputer network containing up 

to eight CPUs, a monitor, a keyboard, and a mouse as installed in a trailer instrument rack plus a 

separate computer, two flat screen monitors, a keyboard, and a mouse installed in either the tractor 

sleeper compartment (APEX-1) or a stand-alone operator’s station (APEX-2 and -3). The computer at the 

operator’s station is networked via modem to the multicomputer to allow file access and transfers. A 

keyboard-video-monitor (KVM) switch also allows the operator to access and run instrument operating 

software on the multicomputer in the trailer. All instrument measurements are recorded on the DAS and 

stored as individual data files. All calculated quantities are determined post-test from the raw data as 

described in Section 5. A clock card is also installed in the master computer, which is used to timesynchronize the remainder of the computers. The master computer clock is set daily to an atomic clock 

that is traceable to the National Institute of Standards and Technology (NIST). 

27
 

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28
 

 

4. Experimental Procedures 

4.1 General Sampling Approach 

The exhaust plume was sampled at a location approximately 15, 30, or 43 m downstream of the engine 

being tested. Sampling was done at the centerline using a single probe (as described earlier). The 

exhaust was cooled and diluted at this location (no less than 30:1, and possibly more) so that, in most 

cases, no special conditioning was required for gaseous and particulate sampling. In addition to on-line 

analyzers, chemical source profiles were developed from time-integrated measurements. The DEAL also 

sampled ambient background about 1.83 m (6 ft) above the roof of the DEAL with a separate system 

used to continuously monitor ambient background concentrations (physical and chemical). 

Ambient conditions such as wind speed and direction, temperature, and relative humidity were monitored 

continuously by NASA-Dryden during APEX-1, by the NRMRL team during APEX-2, and by the University 

of Central Florida (Volpe Center) during APEX-3. 

4.2 Pre-test Procedures 

4.2.1 System Cleaning and Leak Checks 

Initial cleaning of the sampling tunnels and lines was conducted by power washing the internal surfaces 

using a dilute solution of laboratory detergent in deionized (DI) water, followed by a DI water rise. After 

power washing, the equipment was allowed to air dry. All port plugs were then removed from the tunnels 

to clean out anything that may have fallen into the cavities. Each sampling line was then capped at both 

ends for transport to the field. 

Following the setup of each sampling system in the field, and prior to any sample collection, positive 

pressure system leak checks were performed on the sampling tunnel inside the DEAL. These leak checks 

were done by placing a cap on the end of the tunnel downstream of the virtual impactor. The cap was 

fitted with a 6-mm union and connected to a cylinder of compressed air that was used to pressurize the 

tunnel. The barb fittings on the outlet side of all of the flow splitters were removed and replaced with caps, 

and all the other ports were sealed. A soap and water mixture was used to detect leaks until the tunnel 

could maintain a positive pressure after shutting off the air cylinder. 

Positive pressure sample system leak checks were also performed on the sample line upstream of the 

virtual impactor and up to the probe inlet. In both cases, a section of the 5-cm sample tube that connected 

to the virtual impactor inside the trailer was removed. The section of sample tube was then replaced with 

a cap that was fitted with a 6-mm union and then plumbed to a cylinder of compressed air. A rubber 

stopper was used to seal the probe inlet. The system was pressurized to about 260 mm mercury (Hg) and 

the valve to the air cylinder was shut off. If the pressure dropped to zero, the system was re-pressurized 

and all the uncontaminated flange joints and other fittings were checked for leaks while pressure was 

maintained on the system. A final check was made to ensure that pressure could be maintained. 

29
 

 

 

4.2.2 Sampling Media Preparation 

All sampling media were prepared in NRMRL’s Fine Particle Characterization Laboratory (FPCL) before 

leaving for the field. Prior to and after sampling, the quartz filters and ELPI substrates shown in Table 4-1 

were stored in aluminum-foil lined, plastic petri dishes inside a laboratory freezer maintained at -50 °C. 

The Teflon filters were stored inside plastic petri dishes, also in the -50 °C freezer. The PUF plugs were 

stored and transported in glass jars with Teflon-lined screw caps. Silica gel tubes impregnated with DNPH 

for collection of gaseous carbonyl compounds and cleaned SUMMA canisters were prepared and 

supplied by the analytical subcontractor, Eastern Research Group (ERG). Carbonyl sampling tubes were 

stored in the freezer before and after sampling and SUMMA canisters were stored under ambient 

conditions before and after sampling. 

Table 4-1. General Analytical Plan 

Type of Analysis Sampling Media Analytical Method 

PM-2.5 mass 47-mm Teflon filters Gravimetric 

PM-2.5 mass Aluminum foil ELPI substrates Gravimetric 

EC/OC 47-mm prefired quartz filters NIOSH 5040 (NIOSH, 2003) 

Semivolatile Organic Compounds 47-mm prefired quartz filters Multisolvent extraction, GC/MS or 

thermal desorption, GC/MS 

Semivolatile Organic Compounds PUF plugs Multisolvent extraction, GC/MS 

Semivolatile Organic Compounds Aluminum foil ELPI substratesa

 Thermal desorption, GC/MS 

Water-soluble ions 47-mm Teflon filters Ion chromatography (IC) 

Elemental composition 47-mm Teflon filters XRF spectroscopy 

Gas-phase organics SUMMA canisters GC/MS, GC/FID 

Gas-phase carbonyl compounds DNPH sampling cartridges HPLC 

a. Collected, but not analyzed, due to insufficient mass 

During transport and in the field laboratory, all sampling media were stored in a small portable freezer 

operated at a nominal temperature of approximately -20 °C. This portable freezer was also used as the 

primary shipping container for the sampling media to and from the sampling site (the freezer was 

operated on generator power en route). Carbonyl sampling tubes were stored in the freezer before and 

after sampling; SUMMA canisters were stored under ambient conditions before and after sampling. 

Although field blank samples were collected and analyzed, no special measures were taken to determine 

sample degradation during storage and shipment. 

Sampling system leak tests were performed prior to transporting the sampling systems to the test site to 

assure that the systems had been cleaned properly and were leak free. A post-test plume tunnel blank 

test was also performed by running the entire system with a HEPA filter installed on the inlet and then 

immediately recovering the samples. Monitoring data for tunnel blank samples were then processed 

exactly like samples collected from the emission source and used to determine if any hysteresis effects 

were present during sample collection requiring post-test correction of the experimental data. 

30
 
 

4.2.3 Particle Instrument Calibration 

The preparation and calibration of source sampling equipment and monitoring instrumentation is essential 

in maintaining data quality. The instrumentation / equipment arrived at the test site pre-calibrated 

according to the procedures contained in the approved QAPP. Calibrated measuring devices (e.g., 

thermocouples, pressure transmitters, and flow meters used with the time-integrated sampling equipment) 

and replacement / repair of parts were also provided. In addition, the quality control (QC) checks outlined 

in Section 4.3.2 were performed upon arrival and before each day of sampling. 

The types of calibrations performed on the PM instruments are generally limited to air flow rate and 

similar parameters as outlined in the applicable instrument manual. The scheduled calibrations for each 

instrument and the associated acceptance criterion for each are shown in Table 4-2. 

4.2.4 Gas Analyzer Calibration 

Both the Model 1302 Photoacoustic Analyzer and the Model 3300A CO2 Analyzer were calibrated prior to 

being deployed to the field and checked daily thereafter. Table 4-3 provides the scheduled calibrations for 

each analyzer. 

Calibration of the photoacoustic instrument is a complicated procedure that requires at least 24 hours of 

continuous sampling to complete. Following the manufacturers recommendations, a single-point 

calibration was performed for each of the three optical filters before the sampling campaign. In the case of 

the photoacoustic analyzer, the QC checks performed during the sampling campaign are detailed in 

Section 4.3.3. In the case of the Milton-Roy CO2 Analyzer used in APEX-2 and -3, a multipoint calibration 

was conducted before being deployed to the field. 

4.3 Field Sampling Procedures 

4.3.1 Continuous Analyzer Operation 

A consistent and rigorous routine was followed to ensure proper operation of all the instruments during 

each sampling campaign. Miscellaneous operating procedures (MOP) were developed for each 

instrument type as outlined in the approved QAPP. These MOPs are included here by reference (EPA, 

2004; EPA, 2005a; EPA, 2005b). The specific measurement protocols used during this aircraft engine 

study are summarized in Table 4-4. 

The first thing to be done in the daily test start-up procedure was to power on the instruments to make 

sure all of the clocks were time synchronized. Some instruments, such as the TEOMs, require a 

stabilization period for their heaters and their flows to reach their set points. Most instruments were left 

“on” continuously throughout the campaign since testing occurred on a daily basis. While the instruments 

were stabilizing, their internal clocks, as well as the master clock in the multicomputer, were synchronized 

with an atomic clock supplied for this purpose. 

4.3.2 Instrumental Quality Control Checks 

To assure proper operation of the laboratory in the field, a number of QC checks were established as 

shown in Table 4-5. A daily checklist was prepared for each sampling campaign; this checklist included all 

of the QC measures shown in Table 4-5, as well as other important instrument operating parameters. The 

checklist was used as part of the laboratory start-up and shut-down procedures. These checklists were 

then stored in a ring binder for later reference. 

31
 
 

 

 

 

 

 

 

 

 

 

Table 4-2. PM Instrument Calibration Schedule 

Instrument Calibration Performed Nominal Frequencya Acceptance 

Criterion 

R & P Series 1105a Main air flow audit Before/after sampling campaign + 10% of set-point 

and 1400a TEOM 

R & P Series 1105a Mass transducer verification Before/after sampling campaign KO = ± 2.5% of 

and 1400a TEOM factory calibration 

RPM-100 QCM Sample flow calibration Before/after sampling campaign ± 10% of indicated 

value 

Dekati ELPI Single point flow audit Before/after sampling campaign 10 ± 0.1 L/min 

TSI Model 3025a CPCb “Aerosol” air flow calibration Before/after sampling campaign 0.03 ± 0.003 L/min 

TSI Model 3025a CPCb “Condenser” air flow calibration Before/after sampling campaign 0.3 ± 0.03 L/min 

TSI Model 3025a CPCb Inlet “high” air flow audit Before/after sampling campaign 1.5 ± 0.15 L/min 

TSI Model 3080 

Classifierc “Sheath Air” flow calibration Before/after sampling campaign ± 10% of set-point 

TSI Model 3080 

Classifierc “By-Pass Air” flow calibration Before/after sampling campaign ± 10% of set-point 

TSI Model 3080 

Classifierc “Impactor” air flow calibration Before/after sampling campaign ± 10% of set-point 

TSI Model 3090 EEPS Single point flow audit Before/after sampling campaign ± 10% of set-point 

Aethalometer Sample air flow calibration Before/after sampling campaign ± 10% of set-point 

PAS 2000 PAH analyzer Sample air flow audit Before/after sampling campaign 2 ± 0.2 L/min 

Time-integrated sampler Air flow calibration Multi-point before sampling; single ± 10% of indicated 

MFCs point audit after sampling value 

Sampling tunnel MFCs Air flow calibration Multi-point before sampling; single ± 10% of indicated 

(plume and background) point audit after sampling value 

a. Frequency of calibration is dependent on whether instrument was new or had recently been returned from the factory 

after service. In either case, the factory calibration was used and no flow calibration was performed prior to use. 

b. Both alone and as part of the TSI Model 3936 SMPS. 

c. Part of Model 3936 SMPS and connected to Model 3025a CPC. 

MFCs = Mass flow controllers 

Table 4-3. Gas Analyzer Calibration Schedule 

Gas Analyzer Type of Calibration Frequency Acceptance Criteria 

B&K Model 1302 

Photoacoustic Analyzer 

(APEX-1) 

Single point calibration using CO and 

CO2 in nitrogen and hexane in zero air 

Zero and span check 

Before/after 

sampling campaign 

Daily 

± 5.0% of certified value 

± 5.0% of calibrated value 

Milton-Roy Model 

3300A (APEX-2 & -3) 

Multipoint calibration using CO2 in 

nitrogen 

Before/after 

sampling campaign 

± 5.0% of certified value 

Zero and span check Daily ± 5.0% of calibrated value 

32
 

33
 


Table 4-4. Available MOPs for On-Line Analyzers 

Parameter(s) Measured Instrument Make/Model MOP Number 

PM-2.5 mass concentration R&P Series 1105a Tapered Element Oscillating Microbalance (TEOM) 1414 
 

PM-2.5 mass concentration 
 R&P Series 1400 Tapered Element Oscillating Microbalance (TEOM) 1415 
 

PM-2.5 mass concentration 
 SEMTECH Model RPM-100 Quartz Crystal Microbalance (QCM) 1425 
 

PM-2.5 number concentration TSI Model 3025a Condensation Particle Counter (CPC) 1412 
 

Particle size distribution Dekati Electrical Low Pressure Impactor (ELPI) 1413 
 

Particle size distribution 
 TSI Model 3934 Scanning Mobility Particle Sizer (SMPS) 1411 
 

equipped w/ Model 3071 Differential Mobility Analyzer 
 

Particle size distribution 
 TSI Model 3936 Scanning Mobility Particle Sizer (SMPS) 1412 
 

equipped w/ Model 3081 Differential Mobility Analyzer 
 

Particle size distribution 
 TSI Model 3090 Engine Exhaust Particle Sizer 1426 
 

“Black”/”blue” carbon Magee Model AE-2 Aethalometer 1416 
 

Surface-bound PAHs 
 EcoChem Model PAS 2000 1417 
 

Carbon dioxide, Hexane, CO Operation of B&K 1302 Gas Analyzer for Tracer Gas Measurements 1418 
 Carbon dioxide, Hexane, CO Performing Zero Check of the B&K 1302 Analyzer 1419 
 

Carbon dioxide Milton-Roy Model 3300A 1427 
 
34
 


Table 4-5. Field Sampling Equipment QC Checks 

Experimental 

Parameter Instrument QC Check(s) Frequency Acc

Sample Extraction / 

Collection System 

Background and plume 

sampling system 

Leak check sampling tunnel and instrument sample lines Before field sampling 

Background and plume 

sampling system 

Electrical ground continuity check Upon initial setup 

Background and plume 

sampling system 

Check major/minor air flow rates with Roots Meter Before sampling campaign ± 

All continuous analyzers and 

samplers 

Establish “tunnel blank” using HEPA filter on tunnel inlets After sampling Record and 

DAS All instruments with digital 

outputs 

All software running and communicating with each 

instrument 

Before each test N

All instruments with analog DASYLAB software running and instruments responding Before each test No 

outputs 

Master computer Set time using atomic clock Daily All com

CO2 concentration Model 1302 photoacoustic 

analyzer or Model 3300A IR 

analyzer 

Zero and span checks Twice daily 

Particle mass concentration Time-integrated samplers Leak check Before each test P

Model 1105a and 1400a 

TEOM 

Install new filter and check frequency (1105a) Daily < 1 (10

Check red fault light on front panel Before each test 

Check status indicator on display (1400a only) Before each test S

Model RPM 100 Check status indicators on front panel Before each test 

Change crystal and zero instrument using inlet filter Before each test Instrument 

Particle number concentration 

(alone and in conjunction with 

an SMPS) 

Model 3025a CPC Check indicator lights for optics, condenser, saturator, liquid 

level, aerosol/total flow 

Zero instrument using inlet air filter 

Before each test 

Daily 

Perform side-by-side comparison in laboratory Before sampling campaign ± 
35
 


Experimental 

Parameter Instrument QC Check(s) Frequency Acc

Particle size distribution Model 3936 SMPS (including 

CPC) 

Check polydisperse aerosol, monodisperse aerosol, and 

sheath air flow set points 

Before each test 

Check CPC reading without voltage scanning Before each test 

Check inlet impactor and clean/grease, if necessary Daily 

Dekati ELPI Check instrument flow on display Before each test 

Zero electrometers (“All Zero”) twice and leave purge pump 

“on” until test begins 

Before each test 

Check charger voltage and current Before each test 

Model 3090 EEPS Check for error messages on front panel display Before each test 

Zero instrument using inlet air filter Before each test Particle coun

Black carbon Aethalometer Perform optical test using optical test strip per operating 

manual 

Before sampling campaign ± 

Check status lights on display for faults Before each test 

PAH concentration Photoelectric Aerosol Sensor 

(PAS) 2000 

Check lamp intensity on display 

Check frequency on display 

Before each test 

Before each test 

Check air flow rate on display Before each test 

Plume temperature (APEX-2) T-type thermocouples Check each by holding hand around sensor to assure 

instrument is responding to temperature change 

Daily Rea

Plume air velocity Pitot tubes and dP cells Blow into pitot inlet to assure instrument response Daily Rea

Wind direction (APEX-2) Wind vane on meteorological 

station 

Orient vane to North Before sampling 
4.3.3 Gas Analyzer QC Checks 

During the APEX-1 sampling campaign, the photoacoustic analyzer response was checked with certified 

calibration gases prior to testing using a procedure that required a minimum of 2 hours for warm up and 

the response check. The procedure first required that the analyzer be allowed to sample air or nitrogen 

for a 30-minute warm-up period before checking its response to the certified calibrations gases. Next, the 

analyzer response was checked while sampling one or more of the three certified calibration gases. The 

calibration gas was introduced as close to the analyzer inlet as possible while maintaining the inlet 

conditions as if the instrument were collecting a sample from the plume tunnel or the bag sampler. The 

analyzer is very pressure sensitive, so introducing the calibration gas under any other conditions was not 

an option. The analyzer response was then checked while sampling from the Tedlar bag in the 

background bag sampler that had been prefilled with nitrogen or one of the certified calibration gases. All 

calibration checks that were performed were done prior to starting a test and are listed in Table 4-6. 

Table 4-6. Photoacoustic Analyzer Response Checks Performed during APEX-1 

Date Direct Response Checks Bag Sampler Bias Response Checks 

4/20/2004 CO2, Hexane, CO CO2, Hexane, CO 

4/22/2004 CO2, Hexane, CO CO2, Hexane, CO 

4/23/2004 CO2 -­

4/24/2004 CO2, Hexane, CO CO2, Hexane, CO 

4/25/2004 CO2 CO2 

4/26/2004 CO2 CO2 

4/27/2004 CO2 CO2 

4/28/2004 -­ -­

4/29/2004 CO2 CO2 

4/30/2004 CO2, Hexane, CO CO2, Hexane, CO 

Table 4-3 provides the intended calibration schedule for the photoacoustic analyzer used to measure 

these gases. As can be seen in Table 4-6, it was not possible to perform all necessary calibration checks 

of the analyzer due to logistical restrictions that limited access to the DEAL either before or after the tests. 

In the case of the Milton-Roy CO2 Analyzer during APEX-2 and -3, the instrument was zeroed and 

spanned before and after each day’s testing. In addition, the analyzer was also used to analyze bag 

samples collected by the University of Central Florida (VOLPE) just prior to the post-test zero and span of 

the instrument. 

4.3.4 Time-Integrated Sampling 

Sample substrates (filters, canisters, PUF, DNPH-impregnated silica gel cartridges) were prepared in 

advance in accordance with the number and type of samples designated in the approved QAPP. During 

preparation of the sample collection media, a unique laboratory identification number was provided for 

each type of medium listed in Table 4-1. This number was recorded in a bound laboratory notebook and 

kept in the permanent record for the study. At the time of loading the media into each sampler prior to 

each speciated test, the laboratory identification number was entered on a special media data form. 

36
 

 

 

These forms list the laboratory identification number and sampling system details. These forms, as well 

as the samples collected in the field, were transferred to EPA’s FPCL or the Eastern Research Group 

(ERG) laboratories upon returning from the field. 

4.3.5 Documentation 

A field project notebook or special data forms were used to record operational parameters of the fine 

particulate sampling systems. Setup and calibration of the instruments was also documented in a bound 

laboratory notebook or stored electronically. All test details including QC checks, engine operation, 

environmental conditions, observations made during sampling, etc., were also recorded either in a bound 

laboratory notebook, on checklists, or on log sheets, as appropriate. All such paper records were kept in a 

ring binder and stored as part of the study archive. All electronic data were stored on the DAS as well as 

archived daily on compact disc (CD). 

4.4 Laboratory Analysis Procedures 

Samples collected for speciated test runs included the following: 

•	 Gas-phase nonmethane volatile organic compounds (VOC) using SUMMA-polished stainless steel 

canisters (ERG); 

•	 Gas-phase carbonyl compound emissions using DNPH-impregnated silica gel cartridges (ERG); 

•	 Gas-phase semivolatile organic compounds (SVOC) using PUF plugs as well as quartz filters; 

•	 PM mass and particle-phase elemental/organic carbon (EC/OC), particle-phase SVOCs, elemental 

composition, and water soluble ions using quartz and Teflon filters plus aluminum foil ELPI substrates 

(collected, but not analyzed due to insufficient mass); and 

•	 PM continuous monitoring data and selected fixed gases over the specified monitoring range. 

The chemical analysis of PM samples collected in the field involved the following laboratory operations: 

•	 Preparation of samplers and sampling array components for field deployment, including 

decontamination of sampling media and weighing filters; 

•	 Maintenance of suitable records covering receipt of samples in the laboratory to final sample 

disposition; 

•	 Cold storage of samples from preparation to analysis and archiving samples for possible future 

reanalysis; and 

•	 Data reduction, data archiving, and reporting results. 

A summary of the analytical methods used is provided in Table 4-7. 

37
 

Table 4-7. Analytical Procedures for Chemical Characterization 

Parameter Measured Analytical Method MOP/SOP Number 

PM mass concentration Gravimetric analysis 2503 

EC/OC Thermal-optical transmittance 2511 

SVOC Preparation of blank substrates 2501 

SVOC Cleaning of PUF plugs 2509B 

SVOC Solvent extraction of quartz filters 2504 

SVOC Solvent extraction of PUF plugs 2509 

SVOC Extract methylation 2505 

SVOC Silylation of methylated extracts 2506 

SVOC GC/MS analysis 2507 

Elemental analysis of Teflon filters X-ray fluorescence analysis 2515 

Water soluble inorganic ions Extraction of Teflon filters 2513 

Water soluble inorganic ions Ion chromatography analysis 2512 

Gas phase air toxics and NMOCs SUMMA canister cleaning ERG-MOR-062 

Gas phase air toxics and NMOCs GC/MS and GC/FID analyses ERG-MOR-005 

Gas phase carbonyls Extraction/analysis of DNPH media by HPLC ERG-MOR-024 

Gas phase carbonyls High performance liquid chromatography ERG-MOR-082 

analysis 

MOP = Miscellaneous operating procedure 

SOP = Standard operating procedure 

HPLC = High performance liquid chromatography 

4.5 Sample Preservation and Storage 

After returning from the field, all sampling media (Table 4-1) except the SUMMA canisters were stored 

continuously at -20 °C or below until extraction and analysis. Samples maintained at this temperature in 

sealed containers with aluminum liners may be safely stored without degradation for long periods of time 

prior to analysis. Procedures for storing and transporting the samples from the point of collection to EPA’s 

FPCL are described in the approved QAPP for each campaign. 

4.6 Post-Test Laboratory Procedures 

The samples of fine PM collected during testing by integrated sampling media were transported in a 

freezer (to minimize sample losses) to the laboratory for chemical analysis. Upon return to the laboratory, 

sampling information such as date for testing, test ID, test conditions, and sampling location of individual 

media were collected and recorded into the sample log system. The instruments and procedures for the 

analyses conducted in the laboratory are described in the following sub-sections. 

4.6.1 PM Gravimetric Analysis 

The PM gravimetric analysis was performed by weighing the individual Teflon filters before and after 

sampling on a Sartorius microbalance with a detection limit of ± 3 μg. The filter weighing was done in 

38
 

accordance with a procedure described by Title 40 of the Code of Federal Regulations (40CFR), Part 53 

(EPA, 2008) for ambient sampling. The method requires that the filter samples be conditioned before 

weighing, by exposure for a minimum of 24 hours to an environmental chamber that is maintained at 20 

to 23 °C and a relative humidity of 30 to 40 percent. To eliminate possible electrical charge from 

accumulating on the surface, both sides of each Teflon filter were exposed to polonium strips for at least 

20 seconds before placing on the balance. 

Before sampling, the blank Teflon filters were tare weighed and placed in Analyslide dishes purchased 

from Pall Gelman with individual IDs. The weight change in the same filter after sampling was then used 

for PM mass emission calculation. 

Note that the PM gravimetric analysis for the Teflon filters collected in APEX-2 was not conducted 

correctly. The laboratory personnel did not follow the procedure to eliminate the static electric charge on 

the Teflon filter before weighing, making all the tare weight results invalid. Therefore, no Teflon filter data 

are presented for APEX-2. 

4.6.2 Elemental Analysis 

After the post-test weighing, the Teflon filters were analyzed using x-ray fluorescence (XRF) to 

quantitatively determine elements in the PM collected on the filters. In the XRF analyses performed by 

NRMRL, each Teflon filter was covered with a 4.0-μm thick Prolene film that was attached using glue. 

The glue was only on the outer rim of the filter and did not interfere with the analysis. This film prevented 

the PM in the sample from falling off the filter under vacuum analytical conditions. A Philips 2404 

wavelength-dispersive XRF spectrometer, running the UniQuant7 program, was used for the analysis. 

The program provided qualitative and quantitative information for elements greater than atomic number 9 

present in the PM sample. 

The metal analyses conducted by EPA’s National Exposure Research Laboratory (NERL) were 

conducted using a commercially available Kevex EDX-771energy dispersive x-ray spectrometer (XRF) 

which utilizes secondary excitation from selectable targets or fluorescers. Teflo filters are easily handled 

because of the supporting ring. The sample is then placed in a custom designed commercially available 

two-part sample frame which snaps together holding the filter securely in place. Up to seven spectra are 

acquired for each sample depending on how many secondary excitation targets are selected. Elements 

with concentrations below three times the uncertainty are flagged with an asterisk (*) on the printed 

record. If the true elemental concentration is zero then the fitting procedure implies that negative and 

positive results are equally probable. Therefore, negative numbers may be reported. 

Although the PM mass data from the Teflon filters were lost during APEX-2, the XRF analysis was 

performed to quantitatively determine elements in the PM collected on these filters. 

4.6.3 Analysis of Water-Soluble Inorganic Ions 

After non-destructive analyses (weighing and XRF), the Teflon membrane filter samples were further 

analyzed using a Dionex DX-120 Ion Chromatograph for isocratic ion analysis encompassing K+

, NH4

+

 , 

Mg+2, Ca+2, NO3

–2, SO4–2, NO2–

, and Cl– in the PM samples collected on the filters. During analysis, each 

individual Teflon filter was first water-extracted by placing it in a vial with 10 mL of HPLC-grade (low 

conductivity) water. The sample was sonicated for 30 minutes. The extract was then introduced at the 

head of the ion-exchange resin column of the IC. The ions in the sample were detected by the 

39
 

conductivity detector and quantified through the use of external standards. The instrument reports the 

ions in concentrations in the water solution; the concentrations were then converted to the mass of ions 

on the filter by multiplying the concentrations by the volume of the extraction water (10 mL). 

4.6.4 Analysis of Organic and Elemental Carbon 

The quartz fiber filter samples were analyzed by a thermal / optical carbon analyzer provided by Sunset 

Laboratory, Inc., for determination of the OC/EC content before undergoing subsequent analysis for 

SVOCs. The OC and EC were analyzed based on NIOSH Method 5040 (NIOSH, 2003). The method is a 

thermal-optical method which proceeds in two stages. First, organic and carbonate carbon are evolved in 

a helium atmosphere as the temperature is stepped to about 850 °C. The evolved carbon is catalytically 

oxidized to CO2 in a bed of granular manganese dioxide (MnO2) and then reduced to methane in a 

nitrogen / firebrick methanator. Methane is subsequently quantified by a FID. In the second stage, the 

oven temperature is reduced, an oxygen-helium mix is introduced, and the temperature is stepped to 

about 940 °C. As oxygen enters the oven, pyrolytically-generated carbon is oxidized, and a concurrent 

increase in filter transmittance occurs. The point at which the filter transmittance reaches its initial value is 

defined as the split between OC and EC. Carbon evolved prior to the split is considered organic (including 

carbonate), and carbon volatilized after the split is considered elemental. The instrument has a lower 

detection limit (on the order of 0.2 μg/cm2

) filter for both OC and EC. 

The new quartz fiber filters usually have an OC background of 2 to 5 μg/cm2

. To cleanse the purchased 

quartz filters of this background OC, they were pre-fired in a kiln at 550 °C for 12 hours before use. The 

clean quartz filters were stored in petri dishes lined with cleaned aluminum foil. Aluminum-foil liners were 

cut to cover the inside surfaces of the petri dishes so that the filters did not directly touch the dish when 

placed inside the lined dishes. The aluminum liners were also baked at 550 °C for 12 hours and then 

compressed into the petri dishes using a plug machined to fit snugly into the dishes. The filters and liners 

were handled with Teflon forceps to avoid any contamination. 

Only a small portion of quartz filter sample was used for OC and EC analysis. To analyze OC and EC 

content, a 1.45-cm2 sample was punched from the quartz filter with a tool specially provided by Sunset 

Lab. The punch from the filter was then placed on the sample holder of the instrument for analysis. The 

analyzer reports the OC and EC contents in μg per cm2

. Since the actual exposure area of quartz filter 

was 13.45 cm2

, the OC and EC masses on the filter were calculated by multiplying the reported OC or EC 

content (μg/cm2

) by 13.45 cm2. 

4.6.5 Analysis of Particle Phase Organic Compounds 

The SVOCs in the PM collected on quartz filters were either solvent-extracted and quantified by GC/MS 

(APEX-2) or thermally desorbed and quantified by GC/MS (APEX-1 and -3). Each of these methods is 

described below. The thermal desorption (TD) methodology is more sensitive and provides lower 

detection limits. Table 4-8 details the operating conditions for the GC, MS, and TD components of these 

systems. 

40
 

Table 4-8. GC, MS and TD Operating Conditions 

GC Operating Parameter Solvent Extract GC/MS TD/GC/MS 

GC Column 60 meter HP5 (0.25 mm 

ID), .25 micron film 

30 meter HP5 (0.25 mm ID), .25 micron film 

Injection mode Splitless Solvent Vent until 0.1 minute using a PTV inlet 

Injector Temperature 300 °C (-100 °C initially, then ramped at 720 °C/min to 300 °C) 

GC/MS Interface 

Temperature 

300 °C 300 °C 

Initial Oven Temperature 65 °C 65 °C 

Initial Oven Hold Time 10 minutes 10 minutes 

Oven Temperature Ramp 

Rate 

10 °C /minute 10 °C /minute 

Final Oven Temperature 300 °C 300 °C 

Final Oven Temperature Hold 

Time 

45 minutes 26.5 minutes 

Carrier Gas helium helium 

Carrier Gas Flow Rate 1.0 ml/minute 1.0 ml/minute 

Split Vent Open Time 0.3 minutes 1.5 minutes 

Split Vent Flow 50 ml/minute 50 ml/minute 

Gas Saver Time 2 minutes 2 minutes 

Gas Saver Flow 30 ml/minute 30 ml/minute 

MS Operating Conditions Solvent Extract GC/MS TD/GC/MS 

Acquisition Mode Scan Scan 

Solvent Delay 12.95 minutes 6.0 minutes 

Low Mass 50 50 

High Mass 550 550 

Sampling rate 2 2 

MS Quad Temperature 150 °C 150 °C 

MS Source Temperature 230 °C 230 °C 

GERSTEL TDS 2 THERMAL DESORPTION OPERATING CONDITIONS 

Temperature Program Solvent Extract GC/MS TD/GC/MS 

Initial Temperature Not Applicable 25 °C 

Initial Time Not Applicable 0.0 minutes 

Delay Time Not Applicable 1.0 minutes 

Ramp rate Not Applicable 10°C/minute 

End Temperature Not Applicable 300 °C 

Hold Time Not Applicable 5 minutes 

TDS Settings Solvent Extract GC/MS TD/GC/MS 

Transfer Temperature Not Applicable 300 °C 

Standby Temperature Not Applicable 50 °C 

Vent Time Not Applicable 1.0 

Desorption Mode Not Applicable Splitless 

Sample Mode Not Applicable Standard 

41
 

 

 

4.6.5.1 Solvent Extraction Methodology 

Sample Extraction and Concentration 

Spiked filters were extracted in five successive 10-min sonication steps. The first two extractions were 

performed with hexane, and then followed by three extractions with a 2:1 mixture of benzene and 

isopropyl alcohol. Filters were sonicated for 10 min at ambient temperature. In addition, the second set of 

quartz filter samples (APEX-2) was extracted in a tertiary solvent mixture of the aforementioned solvents 

for three separate sonications for times of 40 minutes, 10 minutes and 10 minutes at ambient 

temperature. The water temperature in the sonicator was monitored and maintained below 32 °C. 

Following sonication, the extract was transferred to the flask of the in-line transfer and filtration apparatus, 

which was thoroughly cleaned before extract transfer. The glass parts, including the quartz wool-packed 

Pasteur pipette, were solvent rinsed and then baked in aluminum foil at 550 °C for at least 12 hours. 

Teflon parts were cleaned by sonication with dichloromethane and then air dried. Following assembly, a 

vacuum system was used to rinse the in-line transfer apparatus with high-purity distilled benzene, which 

was pulled through the Teflon transfer line and quartz packed pipette, and into the flask. The rinse 

benzene was discarded, and the flask was then re-rinsed and then reinstalled. The extract was 

transferred to the flask by connecting a vacuum of approximately 10 cm of mercury via the corrugated 

Teflon tubing connected to the sidearm. All five extracts were collected together in the same flask. 

The extract was then transferred and concentrated in the test tube of the Zymark concentrator instrument. 

In the instrument, extract was concentrated by passing a gentle stream of pure nitrogen over the surface 

of the liquid to evaporate the liquid to a total volume of 0.5 to 0.75 mL. The water bath temperature of the 

concentrator was kept between 35 and 40 °C. After concentration, the extract was quantitatively 

transferred to a clean amber vial and further concentrated by nitrogen blow-down to approximately 300 

μL. Concentrated extract was stored in the vial with a Teflon-lined cap in a freezer until derivatization and 

analysis. 

Extract Methylation 

Each concentrated extract was split into two fractions: neutral and methylated. The sample was split by 

measuring the total volume of the concentrated extract with a thoroughly cleaned gas-tight volumetric 

syringe and then recording total volume. Half of the sample was returned to the original vial, and the other 

half was placed in a second cleaned vial and labeled for methylation. 

Methylation was performed to yield methyl esters of fatty acids that would otherwise not be eluted from 

the GC column. The methylation was accomplished by adding approximately 10 μL of high-purity 

methanol and 100 μL of diazomethane solution to the methylation fraction of extract. After the reaction 

was complete, the methylated extract was reconcentrated by nitrogen blow-down to the original volume of 

aliquot before methylation. The methylated extract was stored in the freezer until analysis. 

GC/MS Analysis 

The extracts were analyzed with a Hewlett-Packard (HP) 6890/5973 GC/MS equipped with a thermal 

conductivity detector (TCD) (HP-G1530A), autoinjector (HP-G1513A), programmable temperature 

vaporizing (PTV) inlet, mass selective detection (MSD) interface, and flame ionization detector (FID; HPG1526A). A 5MS GC column was used to separate the various organic compounds in the sample. 

42
 

Ultrapurity helium was used as the carrier gas. The GC/MS operating conditions were summarized in 

Table 4-8 above. 

Positive identification of a compound via GC/MS was confirmed when the GC retention time and mass 

spectrum of the unknown compound matched those of an authentic standard compound under identical 

instrumental conditions. 

For quantification of the target marker compounds by GC/MS, known quantities of deuterated internal 

standards were included in each quantification standard and were spiked into each sample. Each 

compound that was quantified by GC/MS is referenced to one or more internal standards so that the 

response of each compound relative to the appropriate internal standard(s) is fixed with only minor 

variation in MS detector response, MS tune parameters, GC injection conditions, and GC column 

conditions. 

4.6.5.2 Thermal Desorption Methodology 

Sample Preparation 

Prior to the TD/GC/MS analysis, each individual quartz filter sample was thawed in a laminar flow clean 

hood (~10 min), placed in a pre-conditioned (at 350 °C, for 12 hr) glass desorption tube (178 mm long, 

6.0 mm outside diameter), and spiked with an appropriate deuterated internal standard suite. Small 0.6

cm2

 sample plugs were taken from each sample rather than attempting to place the entire 47-mm filter 

inside the desorption tube. Care was taken to use a suitably small sample size (determined by OC/EC 

analysis) so that the column capacity was not exceeded. The number of sample plugs taken was directly 

related to the OC/EC value. 

Thermal Desorption 

Once spiked with internal standard, the glass tube and sample were immediately inserted into a TD 

system (TDS2, Gerstel Inc., Baltimore, MD). The TD is directly interfaced to a GC/MS (Model 6890/5973; 

Hewlett Packard; Pal Alto, CA). The thermal extraction was achieved by ramping the TD oven 

temperature from 25 to 300 °C at 10 °C/min; pyrolytic degradation of organic compounds was minimized 

by avoiding temperatures greater than 300 °C. Helium (50 mL/min) was passed over the sample 

throughout the splitless mode desorption. This step facilitated analyte removal from the particle matrix. 

Desorbed target components passed through a short (152 mm), heated (300 °C) inert steel (SilcoSteel) 

transfer line and were trapped on a cryogenically cooled (-100 °C, liquid N2) programmable temperature 

(PTV-Solvent Vent Mode) inlet system (CIS), also operating in splitless mode. The inlet liner was packed 

with a glass wool to enhance cryofocussing of the analytes. 

GC/MS Analysis 

Upon completion of the desorption step, the TD oven was rapidly cooled with liquid nitrogen to ambient 

temperature (25 °C). The CIS was then ballistically heated (720 °C/min) to 300 °C, to transfer the 

analytes in plug form to the ultra-low bleed 30-m DB 5 GC capillary column [5% diphenyl / 95% dimethyl 

siloxane copolymer stationary phase (30-m length, 0.25 μm film thickness, 0.25 mm i.d.)]. The GC oven 

temperature was held at 65 °C for 10 min, ramped at 10 °C/min to 300 °C, and then held constant for 41.5 

min. The MS detector was operated in full scan mode (50-500 amu, 3 scans/sec). Enhanced Chemstation 

(V. B.01.00, Hewlett Packard) software was used to control the GC/MS and CIS and for data acquisition. 

Gerstel MASter (Version 1.76x5) software was used to monitor and control the TD operation. 

­

43
 

Quantification of target PAHs, alkanes and hopanes was accomplished through comparison with a 

calibration database of response ratios formed from the certified authentic and isotopically labeled 

internal standard suites. The GC/MS and TD operating conditions were summarized in Table 4-8 above. 

A three-level calibration range was used to quantify sample concentrations. Tube blanks were analyzed 

prior to every sample to determine the cleanliness of the TD system prior to each sample. Mid-level check 

standards were analyzed along with the samples to determine system accuracy throughout the analysis 

period. 

4.6.5.3 Analysis of PUFs 

Semivolatile organic compounds are partitioned between gas phase and particle phase. The phase 

distribution depends on the sampling conditions. As a result, there is no clearly defined cut between the 

gas phase and particle phase. The PUF plugs were installed directly downstream of the quartz filters for 

collecting the SVOCs that had not been caught by the quartz filters. 

The PUF plugs used for the tests were purchased from a plastic product company and contained high 

backgrounds of various organic compounds. Although these PUF plugs were pre-extracted with solvents, 

they were still not clean enough to be used for chemical analysis. Therefore, the speciation results of 

these PUF samples are not reported here. 

4.7 Analysis of Gas Phase Samples 

4.7.1 Analysis of SUMMA Canister Samples 

Analysis of the VOC canister samples was performed by ERG as outlined in SOPs ERG-MOR-005 and 

ERG-MOR-062. Gaseous samples collected in canisters were analyzed using a GC/MS and GC/FID. This 

approach is a combination (i.e., the ERG concurrent method) of EPA Method TO-15 (USEPA, 1999a) and 

EPA’s "Technical Assistance Document for Sampling and Analysis of Ozone Precursors" (USEPA, 1998), 

used to resolve air toxics and hydrocarbon species. The concurrent methodology is performed by 

simultaneously analyzing an injected aliquot of pre-concentrated whole air sample by two separate 

techniques. The FID analysis provides a determination of speciated NMOCs (SNMOCs) and allows a 

calculation of total NMOC concentration. A list of target analytes and their detection limits for Methods 

TO-15 and CB-4 are provided in Tables B-1 and B-2, respectively, of Appendix B. 

4.7.2 Analysis of DNPH-Impregnated Silica Gel Cartridges 

Carbonyl samples collected on DNPH-impregnated silica gel cartridges were extracted and analyzed by 

ERG using a High Performance Liquid Chromatograph (HPLC) with an ultraviolet (UV) detector as 

outlined in SOPs ERG-MOR-024 and ERG-MOR-082. Analysis of DNPH-impregnated silica gel cartridge 

samples was performed using a modification of EPA Method TO-11A (USEPA, 1999b) to incorporate 

additional compounds and generate a value for total unidentified carbonyl species as well as total 

identified species. Target carbonyl compounds and their detection limits for this program are provided in 

Table C-1 of Appendix C. 

4.8 Determination of Particle Line Losses 

Particle losses inside the long sample extraction system between the 30-m probe inlet and the virtual 

impactor inside the DEAL were a major concern. Therefore, an experiment was designed to create a 

representative test aerosol that could be sampled using the exact configuration of the DEAL sample 

44
 

extraction system that was used during each campaign. To determine the particle losses in the system, 

the particle size distributions and the number concentrations were measured and recorded using the TSI 

Model 3090 Engine EEPS at two locations: (1) at the probe inlet and (2) inside the DEAL immediately 

upstream of the virtual impactor. The sample extraction system configuration was set up exactly the same 

for APEX-2 as it was during APEX-1, except that there was an additional 3 m (10 ft) of tubing added to 

the configuration. 

Note that the line loss experiment could not simulate the exact sampling conditions occurring in the 

engine exhaust plume during the three APEX campaigns. The experiment also was unable to reproduce 

any aerosol aging effects in the line which might have been present during emissions sampling. 

4.8.1 Experimental Setup and Preparations 

The site chosen for the particle loss experiment was the open burn facility that has been used to research 

emissions from controlled open burns and is located at the NRMRL research facility in RTP, North 

Carolina. The facility was already equipped with the capability to introduce and mix an exhaust stream 

and dilution air into an enclosure with inside dimensions of 3 m deep, 3.7 m wide, and 2.4 m high. Figure 

4-1 shows the front wall of the open burn facility. The exhaust from the DEAL’s Kenworth diesel tractor 

was introduced using a 7.6-m length of 15-cm flexible stainless steel tubing. One end of the flexible tubing 

was connected to the tractor exhaust stack and the other end inserted into an existing 20-cm duct through 

the top right corner of the front wall. The ambient dilution air was introduced with a blower mounted 

through the left side wall. 

Figure 4-1. Open burn facility. 

The sample was extracted through the front wall under the window using a 3-m section of 5-cm tubing 

connected to a short section of 5-cm stainless steel flex tubing before attaching to a tee and then the 

sample probe. The EEPS was allowed to draw the necessary sample flow from a bulkhead fitting and a 6­

mm tube installed in the branch of the tee immediately upstream of the probe inlet as shown in Figure 

4-2. 

45
 
Figure 4-2. Line loss sample location at probe inlet. 

A small service cart was used as a rolling work surface on which the EEPS and a laptop computer were 

positioned. A Dell Latitude D400 Laptop equipped with an Intel 1.4 GHz processor and 512 MB of RAM 

running Windows XP version 2002, SP2, was used to run the EEPS software and to record the data. 

All of the 5-cm stainless steel tubing used was cleaned with soap and water then rinsed using a pressure 

washer prior to each experiment. To prepare the sampling tunnel inside the DEAL for the line loss test, all 

the small tubing connecting the equipment to the splitters was removed, and all the splitter outlets were 

plugged. 

4.8.2 Sampling Procedures 

For all APEX sampling configurations, positive pressure leak checks were performed by pressurizing the 

system to about 5 psig and allowing the system to maintain this pressure for 15 to 30 min. After 

establishing that the system was leak free, the diesel tractor was started allowing the exhaust to enter the 

open burn facility, and the blowers in the DEAL sample extraction system were turned on. The system as 

a whole was allowed a minimum of 30 min for a conditioning period before sampling was started at the 

first location. Six 10-min measurements were recorded at five locations as shown in Figure 4-3. Table 4-9 

lists the sampling locations and the order in which they were sampled. 

Using the EEPS data collected, a series of penetration curves was generated for the APEX-1, -2, and -3 

sampling systems. These curves were used during data reduction to correct the PM results for particle 

losses in the sampling lines. Procedures for derivation of the penetration curves are outlined in Section 

5.5 below. 

46
 

 

 

 

 

Figure 4-3. Sampling locations for particle line loss experiments. 

Note: the numbers 1-6 indicate EEPS sampling locations. 

Table 4-9. Particle Line Loss Sampling Location Descriptions and Sequence 

Location Location Description Sampling Sequence 

Probe Inlet Point where exhaust was introduced to the system 1, 6 

Splitter # 1 First Splitter in the DEAL sampling system downstream of 4 

the virtual impactor major flow outlet 

Splitter # 2 Middle Splitter in the DEAL sampling tunnel 5 

Splitter # 3 Splitter farthest downstream in the DEAL sampling tunnel 3 

Virtual Impactor Exit - Outlet of the minor flow from the virtual impactor 2 

Minor Flow 

47
 

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48
 

 

 

5. Data Analysis 

The post-test data analysis included the following: 

• a series of data reduction procedures; 

• calculation of count and mass emission indices for PM, gas-phase and particle-phase compounds; 

• determination of particle size distribution; 

• calculation of Data Quality Indicator (DQI) goals; and 

• calculation of a correction factor for particle losses in sampling lines. 

A discussion of the performance of each of these steps is provided below. 

5.1 Data Reduction Procedures 

The data reduction procedures were applied to the determination of total PM-2.5 mass concentration, 

EC/OC, and SVOC data. Each procedure is described in the following subsections. 

5.1.1 Total PM-2.5 Mass Concentration 

Total PM-2.5 mass concentration in jet engine exhaust was measured directly by the TEOM, QCM, and 

47-mm Teflon filters. The TEOM and QCM give a continuous measure of PM mass concentration, 

whereas the Teflon filter provides total time-integrated PM mass concentration. 

The TEOM and QCM data processing was straightforward. The average total PM-2.5 mass concentration 

was calculated by averaging the readings over the sampling time specified for either an individual power 

condition or the entire test. For the TEOM, there is a set of readings corresponding to each of three times 

(10, 30, and 60 s). Only the 60-s average data were used. 

The PM-2.5 mass collected on a Teflon filter substrate during sampling was determined by weighing the 

filter before and after sampling. The total PM-2.5 mass concentration is obtained by dividing the PM mass 

collected on the filter by the total air volume pulled through the filter during sampling. The flow rate of 

sample gas through the Teflon filters is measured by a mass flow meter with the total volume of sample 

gas between two consecutive readings calculated by 

Vi = Qi (ti+1 − ti ) (5-1) 

where 

Vi = flow volume over the time between ti

 and ti+1 (L) and 

Qi = flow rate reading at t = ti

 (standard L/min—sLpm). 

49
 
 

 

The total flow volume is then the sum of the time-interval flow volumes over the entire sampling time. 

Thus, the total PM-2.5 mass concentration is given by 

M PM 2.5 (1000) CPM 2.5 = (5-2) ∑Vi 

where 

CPM2.5 = total PM-2.5 mass concentration (mg/m3

) and 

MPM2.5 = PM-2.5 mass collected on the filter (mg). 

A background correction is made by subtracting the PM-2.5 concentration determined from the 

background sampling system from the total PM-2.5 mass concentration obtained above. 

5.1.2 Elemental Carbon/Organic Carbon 

The thermal-optical EC/OC analyzer measures the masses of EC and OC collected on quartz fiber filters 

in units of μg/cm2

. Thus, the total EC and OC concentrations for each quartz filter are calculated by 

multiplying the EC or OC reading by the exposed filter area, and then dividing by the total airflow volume 

passing through the filter during the sampling period as 

M EC AF CEC = (5-3) Qinst t 

M OC AF COC = (5-4) Qinst t 

where 

CEC = mass concentration of EC (μg/L), 

COC = mass concentration of OC (μg/L), 

MEC = mass of EC per unit area of filter (μg/cm2

), 

MOC = mass of OC per unit area of filter (μg/cm2

), 

AF = exposed filter area (cm2

),

 Qinst = sample flow rate through the filter (sLpm), and 

t = sampling time (min). 

The mass ratio of EC to total PM-2.5 (REC) and the ratio of OC to total PM-2.5 (ROC) are 

⎛ CEC R = ⎜

⎜ ⎞

⎟

⎟100% (5-5) EC ⎝CPM 2.5 ⎠
 

⎛ COC ROC = ⎜

⎜ ⎞

⎟

⎟100% (5-6) 

⎝ CPM 2.5 ⎠

50
 

 

 

 

and the percentage of OC (ROC/TC) in the total carbon (TC) is 

M OC ROC / TC = ⎛

⎜

⎜ ⎞

⎟

⎟100% (5-7) 

⎝ M EC + M OC ⎠

where CPM2.5 is the total PM-2.5 mass concentration in μg/L. 

5.1.3 Semivolatile Organics 

For APEX-2, the particulate and gas phase SVOCs collected on quartz filters and PUF plugs were 

extracted with solvents and concentrated. The concentrated extracts were then analyzed by GC/MS. 

Before analyzing the samples, calibration was conducted using deuterated internal standards and 

quantification standards to determine the response factor for each compound. The response factor for a 

specific compound is calculated from the calibration by 

AqxCd x RF = (5-8) x Ad xCqx 

where 

RFx = response factor of compound x, 

Aqx = area counts of compound x obtained from calibration chromatogram, 

Adx = area counts for appropriate deuterated internal standard obtained from calibration 

chromatogram, 

Cdx = concentration of appropriate deuterated internal standard (ng/μL), and 

Cqx = concentration of compound x in quantification standards (ng/μL). 

With known response factors, the mass of compound x in the sample extract is calculated from the 

analytical results by 

AexCd xVd

M = (5-9) x Ad x RFx 

where 

Mx = mass of compound x in the sample extract (ηg), 

Aex = area counts of compound x for the extract obtained from analytical chromatogram, 

Adx = area counts of the appropriate deuterated internal standard obtained from analytical 

chromatogram, and 

Vd = volume of deuterated internal standards spiked onto the sample (μL) 

Once the mass of each compound in the sample is determined from the GC/MS analysis, the mass 

concentration of compound x in the sample flow is given by 

Mx 

Q

Cx = (5-10) 

instt 

where Cx is the species mass concentration collected by the filter (ng/L). 

51
 
 

 

 

5.2 	 Calculation of Count and Mass Emission Indices for PM, Gas-Phase and 

Particle-Phase Compounds 

5.2.1 PM Calculations 

The PM-2.5 number emission index (EI), expressed in number of particles per kg of fuel burnt, EIN, was 

calculated from the background-corrected particle number and carbon dioxide concentrations measured 

by assuming that the amount of fuel burned can be approximated from the amount of CO2 produced due 

to the fuel burning. The equation derivation for EIN calculation is shown as below. 

 

 

6 3 3 ⎛ particles ⎞ 10 cm ⎛ m ⎞ C ⎟⋅ ⋅Q⎜ ⎟ N ⎜ 3 3 ⎜ ⎟ ⎝ cm ⎠ m ⎝ hr ⎠ EI N ( particles / kg) = 3 CCO 2 ( ) % ⎛ m ⎞ kmol 12.01kg 1 ⋅Q⎜ ⎟⋅ ⋅ ⋅ ⎜ ⎟ 3 100 ⎝ hr ⎠ 24.06m kmol fC 

106 200.3⋅ ⋅CN ⋅ fC = (5-11) CCO2 

where 

CN = background corrected particle number concentration (particles/cm3

), 

CCO2 = background corrected CO2 concentration at sampling point CN (%), 

fC	 = fraction of carbon in fuel (g/g fuel), 

24.06 = volume (m3

) per kg-mol of ideal gas at 20 °C, 

12.01 = molecular weight of carbon (kg/kmol), 
 

Q = plume flow rate (m3

/hr), and 
 

200.3 = a combined constant for unit volume and weight corrections 

The PM-2.5 mass emission index expressed in particulate mass per kg of fuel burnt, EIM, was calculated 

from the loss and background corrected particle mass concentration using 

200.3⋅CPM 2.5 ⋅ fC EI M (mg / kg) = (5-12) CCO2 

where 

CPM2.5 = background corrected particle mass concentration (mg/m3

) and

 CCO2 = background corrected CO2 concentration at sampling point CM (%). 

The PM-2.5 mass emission rate expressed in mg of particulate mass per second, ERM, was calculated by 

multiplying the emission index by the corresponding fuel flow rate using 

FF ERM (mg / sec) = EI M ⋅	 (5-13) 3600 

where 

EIM = PM emission index (mg/kg) and 

FF = fuel flow rate (kg/hour) as provided by the aircraft operator. 

52
 
 

 

5.2.2 Gas-Phase Calculations 

With one modification, Equation 5-12 could be used to perform the calculations for the gas-phase 

compounds determined from the time-integrated sampling and consequent GC/MS analyses. The term 

CPM2.5 was replaced with the term Cgx, which is the mass concentration of each organic gas-phase 

compound (Equation 5-14). This substitution allowed the emission indices for individual particulate 

organic compounds to be calculated. 

200.3⋅Cgx ⋅ fC EI M (mg / kg) = (5-14) CCO2 

where 

Cgx = mass concentration of each individual organic gas-phase compound (mg/m3

) 

CCO2 = background corrected CO2 concentration at sampling point CM (%). 

5.2.3 Particle-Phase Calculations 

With one modification, Equation 5-12 could also be used to perform the calculations for the organic and 

inorganic particle-phase elements determined from the integrated sampling and consequent analyses 

(OC/EC analyzer for OC/EC, solvent extraction and TD for organics, and XRF for inorganics). The term 

CPM2.5 was replaced with the term Csx, which is the mass concentration of each particle-phase element 

(Equation 5-15). This substitution allowed the emission indices for individual organic or inorganic particlephase elements to be calculated. 

200.3⋅C ⋅ fC EI M
 

(mg / kg) = sx (5-15) CCO2
 

where 

Csx = mass concentration of each individual particle-phase element (mg/m3

) 

CCO2 = background corrected CO2 concentration at sampling point CM (%). 

5.3 Determination of Particle Size Distribution 

The Nano-SMPS, long SMPS, EEPS, and ELPI were used to determine the particle size distributions 

under various operating conditions. Both the ELPI and long SMPS were found not to be entirely suitable 

for measurement of the jet engine particle size distribution due to their instrument size ranges (0.03 to 10 

μm for ELPI and 0.01 to 0.4 μm for the long SMPS). Only the Nano-SMPS and EEPS showed the 

capability of covering the entire particle size range of jet engine PM (primarily between 3 and 100 nm). To 

obtain an average particle size distribution for an engine power setting, an average was calculated for the 

dN/dlogDp data for each size bin recorded under the same power level. The average dN/dlogDp data for 

each power setting was then smoothed over the entire size range by using the “supsmooth” function 

provided by MathCad 2001 Professional. Once the particle size distribution was determined, the total 

particle number concentration and particle number geometric mean diameter were calculated for the test 

using Equations 5-16 and 5-17, respectively. 

53
 
 

K
 


i 1
 


∑=

( ddN 

⎛

⎜

⎜

⎜

⎜

⎜

=1

GMD ⎝ = 10

log Dp)i log DP )i N (5-16) T =
 
 ×
 d 

d log Dp 

(

)i ×log Dpi 

K ⎞

⎟

⎟

⎟

⎟

⎟

⎠

∑( ) ( i dN d log Dp ×

i 

NT 

(5-17) 

where 

NT = total particle number concentration (particles/cm3

), 

DP = particle size (nm), 

K = number of size bins, and 

GMD = geometric number mean diameter (nm). 

In order to determine the particle mass emission index from the measurement of particle number 

concentrations, Equation 5-18 was used to convert the particle loss and background corrected dN/dlogDp 

into the dM/dlogDp for the i

th size bin. 

(dM / d log Dpi ) = 0.5236×1012 ⋅(dN / d log Dpi )⋅ Dpi 

3 (5-18)
 

where 

Dpi

 = particle size of the i

th size bin. 

The particle mass concentration was then calculated using 

K

=
 ⋅ )] ∑ i

i =1

5.4 Calculation of Data Quality Indicator Goals 

The DQI goals are specific criteria used to quantify how well the collected data meet the appropriate data 

quality objectives. The definitions and calculations for accuracy as expressed in terms of bias, precision, 

and completeness are described below. 

Precision—Precision is the agreement between a set of replicate measurements without assumption of 

knowledge of the true value. Precision is expressed as percent relative standard deviation (RSD) and can 

be determined using 

C [( M dM / d log Dp (5-19) i ) (d log Dpi 

⎛

⎜

⎜

⎝

RSD=
 Standard Deviation of Replicate Measurements 

Average of Replicate Measurements 

⎞

⎟

⎟

⎠
 

100 (5-20) 

54
 

 

Bias—The degree of agreement between an average measurement and an accepted reference or true 

value, expressed as a percentage of the reference or true value. Accuracy DQIs must include systematic 

errors associated with the sampling process. 

⎡(Averaged Measured Values) − (Known Value)⎤ % Bias = 100 (5-21) ⎢ ⎥ Known Value ⎣ ⎦

Completeness—Completeness expresses the percent of acceptable data collected, using 

⎛ Amount of Valid Data Collected ⎞ %Completeness = ⎜

⎜

⎝ Intended Collectable Data ⎟

⎟100 

⎠

(5-22) 

5.5 Particle Loss Correction 

During the APEX testing, the gas and particulate samples emitted from the jet engines were transported 

through a long sampling line to the DEAL. The sampling line length, number of bends, etc., were slightly 

different for each of the three APEX sampling campaigns with the samples subjected to particle losses 

due to diffusion and inertial impaction during transport. In addition, particle losses could also occur in the 

DEAL sampling tunnel, though the losses were expected to be much less in comparison to those in the 

sampling lines. A post-test experiment was conducted to determine the total particle losses for samples 

travelling from the tip of the sampling probe to the splitters in the DEAL sampling tunnel. By measuring 

the particle number concentrations at the two locations for each particle size channel, the particle 

penetration for that particle size was calculated using 

CN ,splitter (dp) P(dp) = (5-23) CN , probe (dp) 

where 

P(dp) = penetration coefficient for particle size dp (dimensionless), 

CN,splitter(dp) = particle number concentration for particle size dp measured by EEPS at splitter, 

particles/cm3

, and 

CN,probe(dp) = particle number concentration for particle size dp measured by EEPS at probe, 

particles/cm3

. 

Figure 5-1 shows the particle penetration as a function of particle size for each sample line during APEX-1, -2, 

and -3. The particle penetration coefficient results were then correlated to particle size. The equations of 

particle penetration for each of the different sampling lines used in the tests are presented Table 5-1. 

55
 

Penetration (-) 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

1 

APEX-1 30-m APEX-2 30-m 

APEX-3 15-m APEX-3 30-m 

APEX-3 43-m 

10 100 1000 

Particle Size (nm) 

 

Figure 5-1. Particle loss experimental results as a function of particle size. 

Table 5-1. Particle Loss Penetration Equations Obtained from the EEPS Measurementsa 

Test Line Penetration Equation R2 

APEX-1 30-m P (-) = 0.0049(logDp)3 – 0.2518(logDp)2 + 0.9531(logDp) – 0.1267 0.996 

APEX-2 30-m P (-) = 0.2148(logDp)3

 – 0.7299(logDp)2 + 3.1391(logDp) – 1.1563 0.997 

APEX-3 15-m P (-) = 0.093(logDp)3

 – 0.7299(logDp)2 + 1.7312(logDp) – 0.3735 0.984 

APEX-3 30-m P (-) = 0.0612(logDp)3

 – 0.7022(logDp)2 + 1.8634(logDp) – 0.5062 0.986 

APEX-3 43-m P (-) = 0.0069(logDp)3

 – 0.4979(logDp)2 + 1.8032(logDp) – 0.7975 0.990 

a. Unit of particle diameter (Dp) is nm in the equations. Caution must be taken when the equations are used for particle 

sizes smaller than 10 nm or greater than 100 nm. 

With the penetration equations in Table 5-1, the particle losses were corrected for the plume particle 

number and mass concentrations measured by various particle instruments. For example, if 

CN, measured(dp) was the particle number concentration measured by an instrument for particle size, dp, the 

corrected concentration, CN, corrected(dp) is 

56
 

CN ,measured (dp) CN ,corrected (dp) = (5-24) P(dp) 

Note that the penetration coefficient data, shown in Figure 5-1, decreased as particle size increased when 

the particle size was greater than 30 to 100 nm. This observation is not consistent with the prediction of 

theoretical particle loss analysis, which predicts that particle losses would not be significantly affected by 

particle size until the particle size was greater than 800 to 1000 nm. Considering the uncertainty in the 

particle loss experimental results, the PM emission results in this report are discussed both with and 

without particle loss correction. NASA has funded research to develop an improved empirical technique to 

determine particle losses in aircraft engine sampling systems (Liscinsky and Hollick, 2008). If an improved 

line loss correction scheme becomes available in the future, the experimental data provided in this report 

may need to be reprocessed to improve data quality. 

57
 

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58
 

6. Test Matrix, Fuel Composition, and Engine Operation 

6.1 Test Matrix and Run Times 

A total of 24 tests were conducted during the three APEX campaigns. The CFM56-2C1 jet engine was 

used throughout the nine APEX-1 tests to investigate the effects of fuel composition on emissions at 

various power settings. Three types of fuel were used: a base fuel (JP-8, or Jet-A1), a high-sulfur fuel 

(JP-8 doped to approximately four times the sulfur content of the base fuel), and a higher-aromatic JP-8. 

During APEX-2 and -3, the fuel composition was not varied as an experimental parameter. During these 

tests, each engine was run with the Jet-A fuel normally used during commercial operations. The same 

engine family used during APEX-1, the CFM56, was also used for all four APEX-2 tests and two of the 

eleven APEX-3 tests. These tests were used to provide further characterization of the fine particulate 

emissions from these widely-used jet engines. 

During APEX-3, five other jet engines of various sizes were studied. These engines included a General 

Electric CJ610-8ATJ turbojet (in use on a Lear 25), Rolls Royce AE3007A1E and AE3007A1/1 turbofans 

(in use on an Embraer ERJ145), a Pratt and Whitney PW4158 turbofan (in use on the A300), and a Rolls 

Royce RB211-535E4-B turbofan (in use on a B757). 

Table 6-1 is the APEX test matrix, which summarizes the details of the 24 tests conducted during 

APEX-1, -2 and -3, plus the aborted end-of-runway sampling during APEX-3 and the three tunnel blank 

runs conducted at the end of each campaign to evaluate potential sampling artifacts. The test number 

designation and run time used for integrated sampling are followed by the aircraft and engine type used in 

each test. The fuel type is indicated for APEX-1; fleet fuel was used for all other tests. In addition, the 

individual power settings (percent rated thrust) used during each test are indicated. The individual power 

settings are approximate values. 

6.2 Fuel Type and Composition 

Table 6-2 summarizes the composition of the fuels used during the APEX campaigns. Three types of jet 

fuels were used in the APEX-1 campaign: a base fuel, a higher sulfur fuel, and a higher aromatic fuel. 

The base fuel, which was a typical JP-8 (Jet-A1) jet engine fuel, was used for EPA-1 and EPA-2, and 

NASA-1 and -1a. A high-sulfur fuel, with approximately four times the sulfur content of the base fuel, was 

used for EPA-3 and NASA-2 and -3. A higher aromatic fuel, with approximately 25 percent more 

aromatics than the base or high-sulfur fuels, was used for NASA-4 and -5. 

During APEX-2 and -3, the normal fleet fuels were used for all engines tested. Table 6-2 illustrates that 

although the sulfur content varied in these fuels (ranging from 132 to 700), these fuels were generally 

similar to the base fuel used in APEX-1. 

59
 
Table 6-1. 

APEX Test No. 

1 EPA-1 

APEX 

Run 

Time 

(min) 

188.53 

Test Mat

Aircraft

DC-8 

rix 

 Enginea

CFM56-2C1 

 Fuel Type 

Base 

4 
 5.5 7 

X 

8.4 

Nominal Percent Rated Thrust 
 

15 30 40 45 60 65 70 

X 

76 80 85 

X 

100
 

X 

 EPA-2 150.7 X X X X 

 NASA-1 197.03 X X X X X X X X X 

 NASA-1a 

 EPA-3 

 NASA-2 

112.3 

149.58 

116.98 

High Sulfur 

X 

X X 

X 

X X 

X 

X X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

 NASA-3 

 NASA-4 

 NASA-5 

143.65 

154.67 

155.5 

High Aromatic 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 
 

2 

Tunnel 

Blank 

T1 

N/A

123.8 

 N/A

B737-700 

N/A 

CFM56-7B24 

N/A 

Fleet Fuel X X 

 

X 

 

X X 

 

X 
 

T4 142.6 X X X X X X 
 

T2 135.8 B737-300 CFM56-3B1 X X X X X X 

 T3 150.5 CFM56-3B2 X X X X X X 
 

3 

Tunnel 
 

Blank 

T1 

N/A

115.6 

 N/A

B737-300 

N/A 

CFM56-3B1 

N/A 

Fleet Fuel X X X 

 

X 

 

X X 

 

X X 
 

T11 

T2 

63.7 

171.4 NASA Lear CJ610-8ATJ Fleet Fuel 

X X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 


 

 T5 

T3 

146.1 

131.48 

Model 25 

Embraer 

(turbojet) 

AE3007A1E Fleet Fuel 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 


 


 

T4 112.43 ERJ145 X X X X X X X 

 T10 

T6 

96.75 

147.58 A300 

AE3007A1/1 

P&W 4158 Fleet Fuel X 

X X 

X 

X 

X 

X 

X 

X 

X X 

X 


 

X 
 

T7 

T8 

76.39 

103.5 B757 RB211-535E4-B Fleet Fuel X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 
 

X 
 

T9 122.43 X X X X X X X X 
 

a. All e

­End-of

runway 

(aborted) 
 

Tunnel 
 

Blank 

ngines we

N/A

N/A

re turbo

 N/A 

 N/A 

fan except

N/A 

N/A 

 as noted. 

N/A
 

N/A

 

 

 

 

 

 

 

 

60
 

Table 6-2. Composition of Fuel Used in APEX Campaigns 

Campaign 

APEX Test No. 

C H S Aircraft Enginea Fuel Type (fraction) (fraction) (ppm) Aromatics 

(vol%) 

Density 

(mg/cm3) 

Heating 

Value 

(MJ/kg) 

1 EPA-1 DC-8 CFM56-2C1 Base 0.8627 0.1369 409 17.5 0.8199 43.2 

EPA-2 

 NASA-1 

NASA-1a 

EPA-3 

 NASA-2

 

 High Sulfur 0.8617 0.1367 1639 

 

17.3 0.8194 

 

43.3 

 NASA-3

 NASA-4 

 NASA-5

 

 High Aromatic 0.8624 0.1370 553 

 

21.8 0.8114 

 

43.3 

2 T1 B373-700 CFM56-7B24 Fleet Fuel 0.8569 0.1430 132 19.7 0.8254 NA 

T4 0.8525 0.1470 412 20.3 0.8080 NA 

T2 B737-300 CFM56-3B1 0.8587 0.1411 206 20.4 0.8202 NA 

T3 CFM56-3B2 0.8522 0.1474 352 22.7 0.8169 NA 

3 T1 B737-300 CFM56-3B1 Fleet Fuel 0.8613 0.1380 700 17.4 0.8044 43.2 

 T11 

T2 

 0.8616 0.1380 400 16.8 0.8109 43.2 

NASA Lear CJ610-8ATJ Fleet Fuel 0.8599 0.1401 0b 14.5 0.7990 43.3 

T5 

T3 

Model 25 (turbojet) 

Embraer AE3007A1E Fleet Fuel 0.8637 0.1360 300 19.9 0.8105 43.1 

T4 ERJ145 

T10 

T6 

 AE3007A1/1 0.8638 0.1360 200 18.6 0.8142 43.1 

A300 P&W 4158 Fleet Fuel 0.8624 0.1370 600 16.5 0.8048 43.2 

T7 

T8 

 

B757 RB211-535E4-B Fleet Fuel 0.8637 0.1360 300 19.4 0.8096 43.1 
 

T9 0.8637 0.1360 300 19.1 0.8090 43.1 
 

 

a. All engines are turbofan except as noted. 

b. Questionable value as reported by NASA. Actual sulfur content should be similar to other APEX-3 tests. 

61
 

 

62
 

One item of note here is the wide variation in sulfur content of the standard fleet fuels used during the 

three tests on the same engine model, the CFM563B1. During APEX-2, Test 2, the fuel sulfur content 

was 206 ppm, whereas for the two APEX-3 tests, the sulfur content was 700 ppm (Test 1) and 400 ppm 

(Test 11), respectively. This wide variation in fuel sulfur is expected to have a significant effect on the 

amount and size of the PM generated by the engine due to gas-to-particle conversion occurring in the 

exhaust. This factor should be kept in mind when comparing test results for these engines. 

6.3 Engine Power Settings 

In all the APEX tests, the emissions were monitored and studied at different steady-state engine power 

settings. These steady-state engine power settings are discussed below for each measurement 

campaign. 

6.3.1 APEX-1 Engine Test Cycles 

During APEX-1, two engine testing matrices were used for each fuel. The “EPA” test matrix followed the 

ICAO-defined landing and take-off (LTO) cycle to simulate aircraft emissions at an airport. This matrix 

consisted of approximately four repetitions of the following power settings: 26 min at idle (7%), 0.7 min at 

takeoff (100%), 2.2 min at climb (85%), and 4 min at approach (30%). Figure 6-1 presents a graph of the 

basic jet engine operating cycle that was proposed by NRMRL for the APEX-1 tests. NRMRL’s primary 

emphasis was speciated measurements of the jet engine emissions with the engine operated in repetitive 

cycles encompassing ICAO LTO power (thrust) settings. These power levels are identical to those used 

during engine certification, except that the EPA sampling included engine start/stop, transitions between 

throttle settings, and bleed air extracted from the engine. Note also that large changes in emissions 

occurred during engine start/stop and power transitions. These large changes in emissions were difficult 

to characterize due to their short duration. 

120

TakeOff 

100 

ClimbOut 

st ercent Rated Thru

80 

60 

40 

P

Approach 

20 Engine Idle Idle Start 

0 

0 5 10 15 20 25 30 35 40 45 

Total Elapsed Time (min) 

Figure 6-1. Proposed APEX-1 EPA test cycle. 
 

The “NASA” test matrix was designed to investigate the effects of engine operating parameters on 

particle emissions. The NASA test matrix included power settings of 4, 5.5, 7, 15, 30, 40, 60, 65, 70, 85 

and 100 percent (restricted to about 93%, but considered to be 100%) of rated thrust. Except for the 100 

percent thrust level, where run-time was limited to 1.5 min, approximately 10 min were provided at each 

power setting to allow for samples to be adequately analyzed. 

Table 6-1 previously indicated the individual power settings used in each of the APEX-1 tests. Figures 

6-2, (EPA tests) and 6-3 and 6-4 (NASA tests) graphically illustrate the sequence of these power settings 

for each test. Note that the EPA and NASA sampling systems were all time-synchronized, so that the 

timestamps associated with the different power settings could be related to the instrument data. 

For EPA-1, Figure 6-2 shows that the test was burdened with disruptions before 14:30, resulting in 

several partial cycles. The test was started at the idle (7%), take-off (100%), and climb-out (85%) power 

settings, followed by a shut-down period from about 12:29 to 13:15 necessitated by a cooling water line 

leak associated with the 10-m probe. Shortly after the second cycle started, a shifting tailwind violated 

safety protocols, requiring the power level to be decreased from 100% to idle (7%) at 13:57. The cycle 

was restarted at the 100% level, but at 14:01, high winds again caused a safety violation that required the 

power level to be dropped to idle. It was not until 14:30 that two full EPA cycles were completed without 

any disruptions. 

In EPA-2 and -3, the jet engine cycle operating cycle was repeated four times and without any 

interruption. However, during EPA-3, an additional power setting was introduced at 75% in the first cycle 

of the test to accommodate the needs of another project participant. 

The six NASA tests were conducted at a number of different power levels as shown in Figures 6-3 and 

6-4. EPA conducted non-speciated sampling during all of the NASA tests. During NASA-1 and -1a, the 

DEAL conducted continuous monitoring only. For the remaining NASA tests (NASA-2, -3, -4, and -5), 

time-integrated sampling was conducted along with the continuous monitoring. For the time-integrated 

samples (see Tables 3-2 and 3-3), it was necessary to use the same media for two sequential tests 

(NASA-2 and -3, and NASA-4 and -5) due to the short run times for these tests. NASA-2 and -3 were 

collected during tests using the high-sulfur fuel and NASA-4 and -5 were collected during tests using the 

high-aromatic fuel. In both cases, once the first test was completed, the time-integrated sample media 

holders were placed in the freezer until the subsequent test was ready to be conducted. 

6.3.2 APEX-2 Engine Test Cycles 

In all four tests of the APEX-2 campaign, the engines were mounted on Boeing 737 airframes owned and 

operated by Southwest Airlines. A CFM56-7B24 was used in Tests 1 and 4, a CFM56-3B1 for Test 2, and 

a CFM56-3B2 in Test 3. For tests T2 and T3, the same media were used for the time-integrated sampling 

(see Tables 3-2 and 3-3), with the exception of the SUMMA canisters, to insure that adequate sample 

mass was collected. 

63
 

64 

120

120

120

11:59:22 

12:05:52 

12:23: 44 

12:24:48 

12:29:09 

13:14:38 

13: 22:07 

13:25:17 

13:29:52 

13:57:29 

14: 00:51 

14:01:56 

14:03:16 

14:08:02 

14:10:28 

14:13:16 

14:30:00 

14:31:38 

14:36:02 

14:45:36 

15:52: 11 

15:53:14 

15: 55:52 

16: 00:24 

8:05:29 

8:07:56 

8:10:20 

8:28:18 

8:29:24 

8:32:40 

8:37:10 

9:04:29 

9:05:28 

9:08:15 

9:13:02 

9:39:38 

9:40:36 

9:43:45 

9:48:25 

10:15:22 

10:16:24

10:19:19

10:24:04

10:38:38 

13:44:00

13:45:10 

13:48:27

14:06:02

14:07:26

14:09:54

14:14:17

14:18:51

14:45:27

14:46:37

14:49:08 

14:53:37 

15:20:03 

15:21:18 

15:23:42 

15:28:17 

15:54:43 

15:55:57 

15:58:22 

16:02:47 

16:12:30

16:13:24 

EPA Test 1 

0 

20 

40 

60 

80 

100 

P e rce n t Rated T h ru st 

Time of Day (hh:mm:ss) 

EPA Test 2 

0 

20 

40 

60 

80 

10 0 

P e rcent Rated Thrust 

Time of Day (hh:mm:ss) 

EPA Test 3 

0 

20 

40 

60 

80 

10 0 

Percent Ra ted Thrust 

Time of Day (hh:mm:ss) 

Figure 6-2. Engine operating cycles for the EPA tests during APEX-1. 
65
 

120

120

120

11:51:50 

11:59:46 

12:02:13 

12:09:11 

12:13:50 

12:42:33 

12:47:00 

12:54:46 

12:59:14 

13:04:46 

13:11:33 

13:19:01 

13:23:15 

13:38:12 

13:58:52 

14:06:47 

14:11:46 

14:25:09 

14:30:07 

14:38:05 

14:42:39 

15:01:59 

8:02:15 

8:03:30 

8:09:02 

8:10:43 

8:14:02 

8:18:34 

8:27:57 

8:29:32 

8:32:49 

8:36:48 

8:41:18 

8:45:56 

8:57:05 

8:58:51 

9:03:04 

9:07:20 

9:16:10 

9:17:57 

9:21:24 

9:25:20 

9:33:19 

9:35:04 

9:38:22 

9:41:59 

9:46:04 

9:50:21 

14:58:46 

15:01:14 

15:10:31 

15:12:47 

15:16:08 

15:20:30 

15:25:03 

15:29:44 

15:33:59 

15:43:03 

15:45:00 

15:48:10 

15:52:33 

15:56:59 

16:01:38 

16:06:02 

16:14:02 

16:16:04 

16:20:16 

16:24:18 

16:28:00 

16:31:59 

16:35:59 

16:39:48 

16:43:38 

16:47:33 

16:51:29 

16:55:54 

0 

20 

40 

60 

80 

100 

Percent Rated Thrust 

NASA Test 1 

(low power) 

Time of Day (hh:mm:ss) 

0 

20 

40 

60 

80 

100 

Percent Rated Thrust 

NASA Test 1a 

(high power) 

Time of Day (hh:mm:ss) 

0 

20 

40 

60 

80 

100 

Percent Rated Thrust 

NASA Test 2 

Time of Day (hh:mm:ss) 

Figure 6-3. Engine operating cycles for Tests NASA-1, -1a, and -2 during APEX-1. 
66 

120

120

120

7:59:19 

8:01:37

8:08:19

8:12:14

8:36:53 

8:41:49 

8:53:50

8:56:00

9:02:46 

9:24:12 

9:32:17

9:40:38 

9:45:58 

9:50:02

9:56:56

10:01:55 

10:08:57 

10:12:59 

10:21:47 

12:47:52 

12:53:52 

12:56:12 

13:02:47 

13:07:08 

13:15:10 

13:25:18 

13:30:04 

13:34:13 

13:42:39 

13:47:09 

13:57:05 

14:01:47 

14: 11:49 

14:16:30 

14:23:39 

14:28:17 

14:36:00 

14:40:18 

14:47:17 

14:57:03 

15:02:05 

15:06:11 

15:13:36 

15:18:24 

8:45:50 

8:51:26 

8:59:41 

9:03:38 

9: 11:09 

9:15:58 

9:28:12 

9:30:43 

9:37:49 

9:43:28 

9:52:26 

10:01:35 

10:07:25 

10: 11:53 

10:20:24 

10:25:00 

10:32: 55 

10:37:27 

10:53:13 

10: 55:31 

11:03:11 

11:07:27 

11:15:43 

0 

20 

40 

60 

80 

10 0 

Percen t Rated T h rust 

NA SA Te s t 3 

Time of Day (hh:mm:ss) 

NASA Test 4 

0 

20 

40 

60 

80 

10 0 

Per c en t Rated Th r u st 

Time of Day (hh:mm:ss) 

NASA Test 5 

0 

20 

40 

60 

80 

10 0 

Per c en t Rated Th r u st 

Time of Day (hh:mm:ss) 

Figure 6-4. Engine operating cycles for Tests NASA-3, -4, and -5 during APEX-1. 
 

The engines were operated in cycles encompassing a series of steady state power settings. To 

investigate the effects of engine operating power on particle emissions, the power levels include those 

used during engine certification (except take-off), cruise, engine start/stop, and transitions between 

throttle settings. Each test consisted of power settings at 4, 7, 30, 40, 65 and 85 percent of rated thrust. 

Except for the 85 percent thrust level, where run-time was 8 min, approximately 10 min were provided at 

each power setting to allow for samples to be adequately analyzed. During the tests, the thrust was 

changed in a stepwise fashion. The thrust was first increased from the lowest thrust level (4%) to highest 

level (85%) under “cold” engine condition, and then decreased under “warm” engine condition, as shown 

in Figure 6-5. Again, the operating cycles used in APEX-2 were similar, but not identical. 

6.3.3 APEX-3 Engine Test Cycles 

The APEX-3 engine test cycles were similar to those for APEX-2. The emissions were monitored while 

increasing the rated power thrust from the lowest level to highest level under cold engine conditions, then 

decreasing the power level from highest to lowest under warm engine conditions. The engine operating 

cycles for APEX-3 are grouped by engine manufacturer and model. For tests T3 and T4, and tests T6 and 

T7, the same sampling media were used for some of the time-integrated samples (see Tables 3-2 and 3­

3), to insure that adequate mass was collected. In both cases, once the first test was completed, the timeintegrated sample media holders were placed in the freezer until the subsequent test was ready to be 

conducted. 

Figure 6-6 presents the engine operating cycles for Tests 1 and 11, which were conducted with the same 

CFM engine model used during APEX-2, Test 2 (CFM56-3B1). The engines were mounted on a Boeing 

737-300 airframe owned and operated by Continental Airlines. The nominal engine power settings were 

4, 7, 15, 30, 45, 65, 85, and 100 percent of rated thrust. Note that in Test 11, only half of the usual cycle 

was completed. 

Figure 6-7 presents the engine operating cycles for Tests 2 and 5 of a General Electric CJ610-8ATJ 

model turbojet engine mounted on a Lear Model 25 airframe owned and operated by NASA. This engine 

was the smallest and least powerful of all of the engines tested. During these tests, the engine power 

setting was set at seven levels: 7, 15, 30, 45, 65, 85, and 100 percent of rated thrust. Note that during 

Test 2, the engine was shut down shortly after reaching maximum power due to high crosswinds. After 

the crosswinds subsided, the engine operating cycle was restarted from the beginning. 

Figure 6-8 shows the operating cycles for AE3007A1E and AE3007A1/1 engines in Tests 3, 4, and 10. In 

all three of these tests, the exhaust was sampled from the engines mounted on the tail of an Embraer 

ERJ 145 commuter jet. In Tests 3 and 4, the aircraft was operated by Continental Express and used a 

Rolls Royce Model AE3007A1E engine. In Test 10, the aircraft was operated by ExpressJet and used a 

Rolls Royce Model AE3007A1/1 turbofan engine. These tests were conducted at seven nominal power 

settings: 8.4, 15, 30, 45, 65, 85, and 100 percent. 

67
 

0 

20 

40 

60 

80 

100 

Rated Thrust (%) 

CFM56-7B24 (T1) 

CFM56-7B24 (T4) 

CFM56-3B1 (T2) 

CFM56-3B2 (T3) 

0:00	 0:30 1:00 1:30 2:00 2:30 3:00 

Elapsed Time (hh:mm) 

                       

   

   

 

 

30

40

50

60

100 100

Test: T1 Test: T11

90 90

80 80

70 70

Percent Rated Thrust

60

Percent Rated Thrust

50

40

30

20 20

10 10

0 0

13:41	 13:59 14:04 17:19 17:28	 17:42 18:01 18:14 18:26 18:37 18:54 19:07 16:18 16:30 16:39 16:56 17:02 17:13 17:16

Time of Day	 Time of Day

       

 

50

60

100 100

Test: T5

15:54 16:16 16:37 16:54 17:11 17:37 17:53 18:10

Time of Day

Test: T2

90 90

80 80

70 70

Percent Rated Thrust

Percent Rated Thrust

60

50

40

30 30

20 20

10 10

0 0

15:44	 16:18 16:24 17:27 17:46 18:0 18:18 18:2 18:31
 


Time of Day
 


40

Figure 6-5. Engine operating cycles for APEX-2. 

Figure 6-6. Operating cycles for CFM56-3B1 engines during APEX-3. 

Figure 6-7. Operating cycles for CJ610-8ATJ engine during APEX-3. 

68
 

69
 

100 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

Percent Rated Thrust 

Test: T3 

22:31 22:40 22:58 23:21 23:38 23:51 0:07 0:17 0:41 

Time of Day 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

Percent Rated Thrust 

Test: T4 

1:17 1:20 1:31 1:43 1:56 2:06 2:25 2:38 2:58 3:09 

Time of Day 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

Percent Rated Thrust 

Test: T10 

0:34 0:41 0:57 1:18 1:31 1:47 1:59 

Time of Day 

Figure 6-8. Operating cycles for AE3007A1 engines during APEX-3. 
Figure 6-9 presents the power cycles for Tests 6 and 7 conducted on the largest and most powerful 

engine, the Pratt and Whitney Model 4158 turbofan. The engine was wing-mounted on the airframe of an 

Airbus A300 owned and operated by Federal Express. A wind speed sensor and warning light were used 

to monitor the exhaust plume velocity on a fence between the engine exit and an adjacent building and 

tarmac. The warning light was blown off the fence during Test 6 at about 65-percent power. The power 

level had to be reduced to idle while the light was reattached to the fence. Testing was resumed, but the 

warning light alarm activated, limiting operation of the engine to about 80-percent power. Therefore, Tests 

6 and 7 were actually conducted at six nominal power settings: 7, 15, 30, 45, 65, and 80 percent of rated 

thrust. 

                       

 

40

50

60

100

30

100

Test: T6 Test: T7

90 90

80 80

70 70

Percent Rated Thrust

Percent Rated Thrust

60

50

40

30

20 20

10 10

0 0

13:45 14:04 14:31 14:48 15:06 15:21 15:38 15:42 15:56 16:18 17:15 17:27 17:40 18:01 18:09 18:22

Time of Day Time of Day

Figure 6-9. Operating cycles for P&W 4158 engine during APEX-3. 

Figure 6-10 shows the engine operating cycles for Tests 8 and 9 of Rolls Royce RB211-535E4-B engines 

mounted on a Boeing 757 airframe owned and operated by Continental Airlines. The same power settings 

were used as for Tests 1 and 11; however, the maximum power level in Test 8 was limited to 85 percent 

because of high crosswinds. 

As can be seen from these graphs, no two tests in any of the sampling campaigns had exactly the same 

operating cycle. This variation in cycles makes it impossible to determine method precision for the timeintegrated measurements. In addition, the lack of consistent engine operation hampered the 

determination of chemical composition for both particle- and gas-phase constituents using methods 

employed here. It could not be determined whether or not the variations seen from test-to-test were due 

to different engine technology or were related to changes in engine operation. Therefore, real-time 

chemical characterization techniques are preferred over time-integrated methods in future tests to allow 

for variations in engine operation. 

70
 

71
 


             

 

 

30

40

50

60

70

100 100

90 90

80 80

70

Test: T8 Test: T9

Percent Rated Thrust

Percent Rated Thrust 60

50

40

30

20 20

10 10

0 0

21:19	 21:28 21:50 21:55 22:12 22:13 22:28 22:45 22:57 20:26 20:39 21:06 21:25 21:40 21:49 22:10 22:20

Time of Day Time of Day

Figure 6-10. Operating cycles for RB211-535E4-B engines during APEX-3. 
This page intentionally left blank. 

72
 

 

 

7. Environmental and Engine Operating Data 

7.1 Wind Speed and Direction 

Any crosswinds experienced during sampling were expected to have an impact on the emissions 

measured in the downstream exhaust plume due to contamination of the background samples with 

engine exhaust and deflection of the plume away from the probe at low engine power. Wind speed and 

direction were monitored during all three APEX campaigns and averaged over the run time for each test. 

Table 7-1 presents these results and includes the RSDs in both wind speed and direction. The RSD is a 

measure of the variation in wind speed and direction experienced during each test. 

Table 7-1. 	 Average and Relative Standard Deviation of Wind Speed and Direction for Individual 

Tests 

Campaign Wind Speed (km/h) Wind Direction (degree) 

APEX Test No Average RSD (%) Average RSD (%) 

1 EPA-1 5 124 133a

 76 

EPA-2 -­ -­ 288 a

 35 

EPA-3 26 16 270 7 

 NASA-1 9 75 109a

 85 

 NASA-1a 2 77 289a

 40 

 NASA-2 11 66 226 28 

 NASA-3 23 20 213 5 

 NASA-4 37 21 224 5 

 NASA-5 7 59 272 37 

2 T1 4 36 306 26 

 T2 2 75 250 40 

 T3 2 60 269 34 

 T4 1 66 263 42 

3 T1 19 16 198a

 3 

 T2 21 31 233 5 

 T3 11 8 224 1 

 T4 11 9 222 2 

 T5 19 52 245 11 

 T6 26 25 282 5 

 T7 23 26 276 4 

 T8 15 50 283 6 

 T9 20 13 225 2 

 T10 14 17 230 3 

 T11 4 21 237 39 

a. Wind direction falls outside of the designated criteria for compressor stall. The data and resulting emissions calculations 

should be used with caution. 

73
 
The direction of the wind, when blowing directly toward the nose of the aircraft, was approximately 240° 

for all of the APEX-1 tests, and 260° for all of the APEX-2 and APEX-3 tests. Based on information from 

the aircraft flight manual, a variation of ± 45° is allowed to avoid engine compressor stall. If the same 

minimum criterion is used to determine acceptable crosswinds to avoid background contamination and 

exhaust plume deflection for the tests, then winds during APEX-1 should fall between 195° and 285°, and 

between 215° and 305° during APEX-2 and APEX-3. 

As shown in Table 7-1, during Test EPA-1 of APEX-1, the average wind direction was 133°. This value 

indicates that this test was conducted during significant crosswinds. In addition, Test EPA-1 had a very 

high RSD in wind speed (124%) and wind direction (76%). Based on these data, the EPA-1 test was 

conducted under poor wind conditions. 

There were two other tests where the wind direction fell outside the criteria defined above: the NASA-1 

test of APEX-1 and T1 of APEX-3. As was the case for Test EPA-1 of APEX-1, caution should be used 

with the emissions data resulting from any test conducted during poor wind conditions. 

Note also that there were periods during other APEX-3 tests that had poor wind conditions, although the 

test averages fell within the stated criteria. These tests with poor wind conditions were tests T2 through 

T5, T8, and T11. 

7.2 Fuel Flow Rate 

Fuel consumption is directly related to engine power output. In the three APEX campaigns, the fuel flow 

rate was supplied by either NASA (APEX-1 and -3) or the airline (APEX-2 and -3) and plotted as a 

function of percent rated thrust for each test. Table 7-2 presents the average fuel flow rates (in kg of fuel 

per hour) at various power conditions, expressed as percentage of rated thrust, for each test. The table 

also includes the aircraft, engine, and type of fuel used for each individual test. Note that the fuel flow rate 

values shown are averages of all the data obtained under the same power condition occurring during a 

test. In some cases, acceptable data may not be available for all periods at a particular thrust level. 

For the APEX-1 campaign, each fuel flow rate is the average value of measurements recorded from 

cockpit instruments at each specified power level. For the APEX-2 and APEX-3 campaigns, the fuel flow 

rates were determined under cold (increasing power in a stepwise fashion) and warm (reducing power in 

a stepwise fashion) engine conditions separately. No fuel flow data were supplied by the airline for T1 of 

APEX-2. Therefore, the data from T4 (same aircraft and engine) were assumed for T1 in the emission 

index (EI) calculations. 

To investigate the effect of fuel type on fuel consumption, the fuel flow rate measurement results were 

compared for the APEX-1 campaign, where three types of jet fuels (base, high-sulfur, and high-aromatic) 

were used. The base fuel was used in EPA-1, EPA-2, NASA-1 and NASA-1a. The high-sulfur fuel was 

used in EPA-3, NASA-2, and NASA-3, and the high-aromatic fuel was used in NASA-4 and NASA-5. All 

these tests were conducted with the same aircraft and same CFM56-2C1 engine. 

Figure 7-1 plots the APEX-1 fuel flow rate data for these three types of fuels against the percent rated 

thrust. Their correlation can be expressed by almost identical linear equations, indicating that the higher 

sulfur and aromatic contents of two of the fuels had no influence on the fuel consumption. This lack of 

influence is probably because the three tested fuels have approximately the same heating values, even 

though their sulfur and aromatic contents were different. 

74
 
75
 


Table 7-2. Summary of Fuel Flow Rates Measured at Different Engine Power Levels 

APEX Test No.a Aircraft Engine Fuel Type Engine Conditions Fuel Flow (kg/h) at Percent Rated Thrustc 4 5.5 7 8.4 15 30 40 45 60 65 70 

1 EPA-1 

EPA-2 

NASA-1 

NASA-1a 

EPA-3 

NASA-2 NASA-3 NASA-4 NASA-5 

DC-8 CFM56-2C1 Base 

350 336 

386 

436 

425 

427 560 

992 

1023 

1012 1252 

1922 

 1998 

2098 225

High sulfur 

345 347 

381 

382 

438 

413 

405 

543 538 

964 

955 986 

1235 1255 

1855 

1846 

2046 2053 

219

220 

High aromatic 345 

345 

381 

395 

401 

410 

545 

545 

960 

989 

1220 

1292 

1850 1930 

2023 

2131 

215

224

2d T4 B737-700 CFM56-7B24 Fleet fuel Coldb 

Warm 

Average 

336 

313 325 

418 

381 400 

 1180 

 1135  1158 

1544 

1498 1521 

 2497 

 2497  2497 

T2 B737-300 CFM56-3B1 Fleet fuel Cold 

Warm 

Average 

341 

345 343 

422 418 420 

 1099 

 1067  1083 

1403 

1367 1385 

 2193 

 2184  2188 

T3 B737-300 CFM56-3B2 Fleet fuel Cold 

Warm 

Average 

372 

368 370 

440 422 431 

 1130 

 1108  1119 

1444 

1412 1428 

 2252 

 2261  2256 

3 T1 B737-300 CFM56-3B1 Fleet fuel Cold 

Warm 

Average 

300 

300 

300 

397 397 

397 

654 

654 

654 

1136 

1136 

1136 

1618 

1618 

1618 

2260 

2260 

2260 

T11 B737-300 CFM56-3B1 Fleet fuel Cold 381 431 622 1090 1530 2179 

T2 NASA Lear 

Model 25 

CJ610-8ATJ 

(turbojet) 

Fleet fuel Cold 

Warm 

Average 

182 

182 

182 

304 

304 

304 

452 

454 

453 

 568 

 568 

 568 

760 763 

762 

T5 NASA Lear 

Model 25 

CJ610-8ATJ 

(turbojet) 

Fleet fuel Cold 

Warm 

Average 

227 

227 

227 

303 

303 

452 

452 

452 

 567 

 567 

 567 

763 

763 

763 

T3 Embraer ERJ 145 AE3007A1E Fleet fuel Cold 

Warm 

Average 

174 

173 

173 

238 

235 

237 

389 

392 

391 

 555 

 563 

 559 

805 

810 

807 

T4 Embraer ERJ 145 AE3007A1E Fleet fuel Cold 

Warm 

Average 

168 

167 

167 

239 

231 

235 

385 

384 

385 

 547 

 549 

 548 

788 

786 

787 

T10 Embraer ERJ 145 AE3007A1/1 Fleet fuel Cold 

Warm 

Average 

179 

178 

178 

233 

231 

232 

372 371 

371 

 524 

 529 

 526 

750 

767 

758 

T6 A300 P&W 4158 Fleet fuel Cold 

Warm 

Average 

610 

368 

489 

1014 

1097 

1056 

2245 

2465 

2355 

3726 

3834 

3780 

5658 

5658 

5658 

T7 A300 P&W 4158 Fleet fuel Cold 

Warm 

Average 

600 

596 

598 

1035 1035 

2230 

 2252 

2241 

3688 3688 

5702 

 5711 

5706 

T8 B757 RB211-535E4-B Fleet fuel Cold 

Warm 

Average 

566 

437 

501 

770 

654 

712 

1191 

1178 

1185 

2109 

2131 

2120 

3178 

3436 

3307 

4750 

4691 

4720 

T9 B757 RB211-535E4-B Fleet fuel Cold 

Warm 

Average 

421 

506 

464 

690 

668 

679 

1221 

1173 

1197 

2004 

2037 

2021 

3068 

3111 

3090 

4479 

4551 

4515 

a Note that bleed air was extracted from the engine during tests EPA-1,-2, and -3 in APEX-1. No fuel flows were recorded by the airline during T1 of APEX-2.
 

b “Cold” refers to increasing power in a stepwise fashion, and “Warm” indicates reducing power in a stepwise fashion. See Section 6.
 c Fuel flows provided by aircraft operator. 
 d Fuel flows for APEX-2, T1, were derived from the same power conditions for T4, since no data were provided by the aircraft operator for this test. 
 
AE3007A1P

76 

Fuel Flow Rate (kg/h) 

3000 

2500 

2000 

1500 

1000 

500 

0 

3500 

High Sulfur 

y = 29.206x + 164.85 

r

2

 = 0.9946 

Base Fuel 

y = 29.004x + 192.38 

r

2

 = 0.9888 

High Aromatic 

y = 29.388x + 164.47 

r

2

 = 0.9928 

Base Fuel 

High Sulfur 

High Aromatic 

0 20 40 60 80 100
 


Percent Rated Thrust
 


Figure 7-1. Effect of fuel sulfur and aromatic content on fuel consumption during APEX-1. 

The fuel consumption rates for different engine types are compared in Figure 7-2. The three lowest thrust 

engines in these tests—Models AE3007A1E and AE3007A1/1 mounted on an ERJ 145 express jet, and 

Model CJ610-8ATJ mounted on a NASA Lear Model 25 airframe—had almost identical fuel consumption 

rates as a function of rated engine thrust. This trend is somewhat surprising since the AE3007 engines 

are rated at almost three times the thrust of the smaller CJ610 on the Lear Model 25. For the CFM56 

engine family, the -7B engine showed the highest fuel consumption, followed by the -3B engine. The -2C 

engine had the lowest fuel flow consumption rate of the CFM56 engines tested. The P&W 4158 turbofan 

engine mounted on an Airbus A300 was the most powerful engine, and operation of this engine resulted 

in the highest fuel consumption rate. The second highest fuel consumer was the RB211-535E4-B 

mounted on a B757 airframe. 

10000 

9000 

8000 

0 20 40 60 80 100 

RB211-535E4-B 

CFM56-7B 

CFM56-3B 

CFM56-2C 

CJ610-8ATJ 

AE3007A1E 

P & W 4158 

AE3007A1/1 

Fuel Flow Rate (kg/h) 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

0 

Percent of Rated Thrust 

Figure 7-2. Effect of engine type on fuel consumption during APEX-3. 
The effects of the engine operating condition (cold and warm) on fuel consumption were investigated by 

plotting the APEX-2 and -3 measurement results obtained under cold engine conditions against the 

measurement results obtained under warm operation conditions and are shown in Figure 7-3. Cold 

conditions were the step-wise increasing of power levels to maximum, whereas warm engine conditions 

were the step-wise decreasing of power levels after the engine had been run at maximum power (refer to 

Figure 6-5 for APEX-2 and Figures 6-6 through 6-10 for APEX-3). The diagonal line represents the data 

that have identical measurement results under both cold and warm conditions. The majority of 

measurement points are closely grouped around the diagonal. Therefore, fuel consumption is not affected 

by whether the engine is operated under cold or warm conditions although differences in emissions were 

consistently observed as discussed below. 

8000 

6000 

4000 

2000 

0 

Cold Engine Fuel Flow Rate (kg/h) 

Warm Engine Fuel Flow Rate (kg/h) 

0 2000 4000 6000 8000 

Figure 7-3. 	 Effect of cold and warm engine operating conditions on fuel consumption during 

APEX-2 and -3. 

7.3 Carbon Dioxide Monitoring 

As discussed in Section 5, the EI calculation requires knowledge of the CO2 concentration at the emission 

sampling location, and both plume and background CO2 concentrations are needed to obtain a 

background-corrected concentration for the EI calculation. For the APEX-1 and APEX-2 campaigns, the 

plume CO2 sampling, as well as other PM sampling, was performed along the plume centerline 30 m 

downstream from the engines. No CO2 measurements were obtained for T1 of APEX-2 due to an 

instrument malfunction. Since there were also no fuel flow data for this test, these parameters were 

assumed to be identical to T4 (same aircraft and engine). During APEX-3, samples were collected at 15, 

30, and 43 m behind the testing engines to investigate the effect of dilution on emissions results. 

As expected, the CO2 concentration was found to be closely correlated with engine rated thrust, which, in 

turn, is related directly to the fuel flow rate. Figure 7-4 is a typical result for the NASA-1 test of APEX-1. 

The background-corrected CO2 concentration and fuel flow rate are plotted with the run time in blue (dark) 

77
 
and red (light) lines, respectively — showing that the CO2 concentration corresponded closely with the 

fuel flow rate during the test. 

CO2 

0.16 3500 

0.14 

Fuel Flow 

CO2

2500 0.13 

0.12 2000 

0.11 

1500 0.10 

0.09 1000 

0.08 

500 

0.07 

0.06 0 

12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 

Time of Day 

0.15 

CO2 Concentration at 30-m (%) CO2

3000 

Fuel Flow Rate (kg/h) 

Figure 7-4. 	 Correlation between CO2 concentration and fuel flow rate during Test NASA-1 of 

APEX-1. 

Table 7-3 summarizes the different power settings used for each APEX-1 and -2 test, along with the 

corresponding background-corrected average CO2 concentration and standard deviation (SD). In these 

campaigns, the sampling was done at the same location, 30 m downstream of the engine. As discussed 

previously, three possible sampling locations were used during the APEX-3 campaign. Table 7-4 presents 

data for APEX-3, similar to the data shown in Table 7-3 for APEX-1 and -2, along with the location where 

the CO2 emissions were sampled for each APEX-3 test. 

The CO2 emissions for the different fuels tested during APEX-1 were studied by plotting the CO2 

concentration data as a function of fuel flow rate. Figure 7-5 shows very similar trends for all three fuel 

types. The CO2 emissions increased as the fuel flow rate increased from 300 kg/hr. The CO2 

concentration reached its maximum when the fuel flow rate was at about 2,800 to 2,900 kg/hr, after which 

the CO2 concentration decreased as the fuel flow rate continued increasing to its maximum. Note that this 

decrease at the highest fuel flow rates (which correspond to the takeoff mode, or 100% thrust) may 

possibly be an artifact of the short run times at this setting. Because the instrumentation experiences a 

slight response lag time, these results may actually be an average of the transition results, and not a true 

reflection of CO2 concentrations at these highest thrust ratings. Whether this observation is an artifact or 

an indication of the actual chemistry occurring at 100 percent thrust, the data collected by APEX-1 

collaborators showed similar trends (Wey et al., 2006). 

To investigate airport CO2 emissions, the APEX-1 results at different engine operation cycles were 

compared. In Figure 7-6, the CO2 concentrations measured were compared at four engine power 

settings: idle (7% rated thrust), takeoff (100% rated thrust), climb-out (85% rated thrust), and approach 

(30% rated thrust) for the three fuel types. Two conclusions can be drawn from these comparisons: 

78
 

Table 7-3. Average Background Corrected CO2 Concentrations at Different Power Settings for 

APEX-1 and -2 

APEX Test No. Parameter The values for APEX-1 are the average at each thrust of all 

the cycles of that test shown in Figures 6-2 through 6-4a 

1 EPA-1 % of Rated Thrust 7 30 85 100 

 Average CO2 (ppm) 

SD (ppm) 

573 

41 

590 

35 

1048 

41 

983 

116 

 

 

 

 

 

 

 

 

 

 

 

EPA-2 % of Rated Thrust 7 30 85 100 

 Average CO2 (ppm) 

SD (ppm) 

449 

57 

573 

46 

1073 

17 

956 

172 

 

 

100 

 

 

 

 

 

 

 

 

EPA-3 % of Rated Thrust 7 30 76 85 

 Average CO2 (ppm) 

SD (ppm) 

181 

74 

370 

59 

787 1026 

70 

740 

250 

 

 

40 65 

 

 

85 100 

 

 

 

 

NASA-1 % of Rated Thrust 4 5.5 7 15 30 

 Average CO2 (ppm) 

SD (ppm) 

542 

155 

448 

47 

462 

97 

533 

61 

596 

25 

692 

38 

901 

--

1025 

--

926 

288 

 

 

NASA-1a % of Rated Thrust 4 60 65 70 85 100 

 Average CO2 (ppm) 

SD (ppm) 

462 

56 

812 

29 

882 

50 

880 

--

1059 

23 

944 

100 

 

60 65 

 

70 85 

 

 

NASA-2 % of Rated Thrust 4 5.5 7 15 30 40 100 

 Average CO2 (ppm) 

SD (ppm) 

536 

50 

249 

--

346 

177 

310 

--

599 

66 

715 

18 

862 

--

922 

26 

941 

--

1088 

38 

1021 

30 

NASA-3 % of Rated Thrust 4 5.5 7 15 30 40 60 65 70 85 100 

 Average CO2 (ppm) 

SD (ppm) 

454 

45 

427 

--

460 

8 

503 

--

632 

22 

699 

13 

880 

--

903 

25 

921 

--

1107 

7 

872 

34 

NASA-4 % of Rated Thrust 4 5.5 7 15 30 40 60 65 70 85 100 

 Average CO2 (ppm) 

SD (ppm) 

307 

56 

274 

--

372 

16 

479 

--

583 

28 

640 

34 

795 

--

833 

13 

877 

--

1010 

43 

1000 

71 

NASA-5 % of Rated Thrust 4 5.5 7 15 30 40 60 65 70 85 100 

 Average CO2 (ppm) 

SD (ppm) 

414 

124 

510 

--

418 

132 

389 

--

597 

32 

634 

76 

841 

--

903 

21 

999 

--

1081 

24 

1111 

86 

APEX Test No. Parameter The values for APEX-2 are the average at each 

thrust in the cycles shown in Figure 6-5b 

2 T2 % of Rated Thrust 4 7 30 40 65 85 7 85 65 85 40 30 7 4 

 Average CO2 (ppm) 

SD (ppm) 

459 

51 

510 

51 

702 

45 

818 

43 

1054 

53 

1430 

59 

496 

41 

1495 

75 

1047 

50 

1461 

55 

816 

42 

697 

44 

539 

50 

530 

57 

T3c % of Rated Thrust 4 7 30 40 65 85 7 85 65 40 30 7 4 

 Average CO2 (ppm) 

SD (ppm) 

600 

65 

552 

59 

712 

49 

822 

48 

1050 

57 

1457 

71 

530 

54 

1464 

78 

1059 

53 

792 

44 

699 

46 

513 

57 

547 

62 

T4 % of Rated Thrust 4 7 30 40 65 85 7 85 65 40 30 7 4 

 Average CO2 (ppm) 

SD (ppm) 

307 

41 

350 

28 

515 

30 

624 

33 

852 

34 

1110 

39 

301 

35 

1120 

43 

848 

35 

604 

34 

510 

34 

316 

33 

272 

43 

a 100% thrust at this test site actually represents 93% rated thrust at standard sea level conditions. 

b 85% thrust is maximum take-off power at this airport. 

c	 Based on an analysis of the criteria gas data by the manufacturer’s representative, this engine may not have been operating per 

specifications. 

79
 

Table 7-4. Average Background Corrected CO2 Concentrations at Different Power Settings for 

APEX-3 

Power Cycle Test The values for APEX-3 are the average at each thrust Reference Parameter No in the cycles shown in Figures 6-6 to 6-10 Figure 

T1 6-6 Sampling Location 30 m 

 Sampling Times 17:31 to 19:07 

 % of Rated Thrust 4 7 15 30 45 65 85 100 4 100 85 65 45 30 15 7 4 

 Average CO2 (ppm) 102 117 137 199 243 315 359 396 99 378 323 265 202 164 115 94 88 

 SD (ppm) 13 13 12 10 16 13 14 11 12 13 13 12 9 7 9 10 9 

T2 6-8 Sampling Location 15 m 30 m 15 m 

 Sampling Times 17:23 to 17:57 17:57 to 18:16 18:16 to 18:33 

 % of Rated Thrust 7 15 30 45 65 85 85 100 7 7 100 65 45 30 15 7 

 Average CO2 (ppm) 19 645 906 1031 1183 1430 870 982 42 360 1633 1272 1051 877 682 39 

 SD (ppm) 3 83 49 41 47 40 55 57 27 185 42 51 39 59 78 2 

T3 6-10 Sampling Location 15 m 

 Sampling Times 22:41 to 00:41 

 % of Rated Thrust 8.4 15 30 45 65 85 100 8.4 100 85 65 45 30 15 8.4 

 Average CO2 (ppm) 78 142 181 228 274 295 313 87 319 272 207 164 160 151 85 

 SD (ppm) 50 50 45 37 41 56 55 54 53 52 33 35 33 34 51 

T4 6-10 Sampling Location 15 m 

 Sampling Times 01:24 to 03:09 

 % of Rated Thrust 8.4 15 30 45 65 85 100 8.4 100 85 8.4 85 65 45 30 15 8.4 

 Average CO2 (ppm) 59 66 101 154 268 358 439 54 387 342 52 297 230 120 64 52 50 

 SD (ppm) 16 17 32 48 54 56 38 3 71 50 5 57 54 41 21 5 3 

T5 6-8 Sampling Location 15 m 30 m 

 Sampling Times 15:55 to 17:03 17:11 to 18:20 

 % of Rated Thrust 7 15 30 45 65 85 100 7 100 85 65 45 30 7 

 Average CO2 (ppm) 115 496 650 654 817 958 1042 190 565 529 488 449 457 177 

 SD (ppm) 42 95 58 55 31 22 23 72 49 42 25 29 25 7 

T6 6-9 Sampling Location 30 m 

 Sampling Times 14:14 to 15:20 then 15:38 to 16:26 

 % of Rated Thrust 7 15 30 45 65 7 65 80 7 7 80 65 45 30 15 7 

 Average CO2 (ppm) 453 512 823 1099 1513 409 1505 1752 426 425 1703 1470 1111 808 531 434 

 SD (ppm) 31 26 21 28 33 46 35 29 39 87 32 37 26 27 28 35 

T7 6-9 Sampling Location 30 m 

 Sampling Times 17:16 to 18:22 

 % of Rated Thrust 7 15 30 45 65 80 7 80 65 30 7 

 Average CO2 (ppm) 491 580 852 1133 1522 1755 482 1759 1515 864 477 

 SD (ppm) 20 30 26 31 36 32 19 29 43 23 29 

T8 6-7 Sampling Location 30 m 43 m 

 Sampling Times 21:37 to 22:20 22:20 to 23:03 

 % of Rated Thrust 4 7 15 30 45 65 85 7 85 4 4 65 45 30 15 7 4 

 Average CO2 (ppm) 134 140 590 820 1039 1346 1563 340 1567 433 350 1022 875 660 475 349 292 

 SD (ppm) 5 3 40 23 25 30 56 56 54 29 36 24 26 29 23 33 40 

T9 6-7 Sampling Location 30 m 

 Sampling Times 20:29 to 22:25 

 % of Rated Thrust 4 7 15 30 45 65 85 100 4 100 85 65 45 30 15 7 4 

 Average CO2 (ppm) 298 419 484 684 855 1091 1365 1469 374 1391 1330 1105 880 688 495 378 344 

 SD (ppm) 67 41 48 43 31 36 41 48 50 50 44 31 37 33 32 46 49 

T10 6-10 Sampling Location 30 m 

 Sampling Times 00:35 to 02:10 

 % of Rated Thrust 8.4 15 30 45 65 85 100 8.4 100 85 65 45 30 15 8.4 

 Average CO2 (ppm) 127 205 282 318 391 444 491 138 500 451 361 326 265 193 156 

 SD (ppm) 80 41 21 35 27 33 29 48 21 23 56 21 39 41 53 

T11 6-6 Sampling Location 30 m 

 Sampling Times 16:20 to 17:15 

 % of Rated Thrust 4 7 15 30 45 65 85 100 

 Average CO2 (ppm) 352 444 641 840 979 1130 1290 1405 

 SD (ppm) 34 43 54 48 31 38 49 55 

80
 

Fuel Flow Rate (kg/h)

CO2 Concentration at 30 m (ppm)

Base Fuel (EPA 1&2)

Hi Sulfur (EPA 3 & NASA 1-3)

Hi-Aromatic (NASA 4&5)

0 

200 

400 

600 

800 

1000 

1200 

1400 

-

-

Base Fuel (EPA 1&2) 

High Sulfur (EPA 3 & NASA 1-3) 

High Aromatic (NASA 4&5) 

CO2 Concentration at 30 m (ppm) 

0 500 1000 1500 2000 2500 3000 3500 

Fuel Flow Rate (kg/h) 

Figure 7-5. Effects of fuel type on CO2 emissions for CFM56-2C1 engine during APEX-1. 

 

 

0 

200 

400 

600 

800 

1000 

1200 

1400 

CO2 Concentration at 30-m (ppm) 

Base Fuel (EPA 1 & EPA 2) 

Hi-Sulfur (EPA 3 & NASA 1-3) 

Hi-Aromatic (NASA 4 & 5) 

Idle (7%) Takeoff (100%) Climb (85%) Approach(30%) 

Figure 7-6. 	 Effects of engine operation cycle on CO2 emissions for CFM56-2C1 engine during 

APEX-1. 

81 
 

1. 	 Except for idle condition, where the base fuel showed a slightly higher CO2 concentration, the 

difference in the average CO2 concentrations for the three different fuels was negligible in comparison 

to the experimental errors. 

2. 	 For all three fuel types, the CO2 emissions were low when the engine was under idle condition. As the 

engine power setting was increased from 7 to 100 percent, the CO2 emissions increased significantly. 

The emissions were highest when the engine moved to climb-out power, and then reduced sharply 

when the engine was changed to approach mode. As discussed above, the slightly lower 

concentrations seen during takeoff (100%) as compared to climb condition may be an artifact of the 

short duration sampling time at the maximum power setting. This result is slightly different from the 

results for fuel flow rate. The fuel consumption was observed to reach the maximum when the aircraft 

was at takeoff power. 

The effects of engine operating temperature (cold or warm) on the CO2 concentration measurements 

were also investigated. In Figure 7-7, the CO2 concentration data measured under cold and warm 

conditions were plotted against the fuel flow rate for selected engines tested during the APEX-3 

campaign. This figure shows that these engines, when warm, had an approximately equal or slightly 

lower CO2 concentration compared to the CO2 concentration that was measured under cold conditions. 

The CO2 concentration data recorded for each of the individual tests were averaged over the run time of 

the test and are presented in Table 7-5 for the three campaigns. This table also includes the 

corresponding standard deviations (SDs). Large SDs shown in the table for all the tests are believed to be 

attributed to the various engine power levels used for each test. The test-average CO2 concentration data 

were used in the calculation of PM EI’s from the integrated samples and will be presented in Sections 8 

(PM Mass Emissions) and 13 (PM-Phase Chemical Composition). 

Fuel Flow Rate (kg/h)

CO2 Concentration (ppm)

2000 

1800 

1600 

1400 

1200 

1000 

800 

600 

400 

200 

0 

1000 2000 3000 4000 5000 6000 7000 8000 

CFM56-3B Cold (APEX-3 T1) 

CFM56-3B Warm (APEX-3 T1) 

RB211-535E4-B Cold (APEX-3 T9) 

RB211-535E4-B Warm (APEX-3 T9) 

P&W 4158 Cold (APEX-3 T6) 

P&W 4158 Warm (APEX-3 T6) 

0 

Fuel Flow Rate 

CO2 Concentration 

Figure 7-7. 	 Effects of cold and warm engine conditions on CO2 emissions for multiple engine 

types. 

82
 
Campaign

APEX-1 

 Test 

EPA-1 

CO2 (ppm) 

Test Average Standard Deviation 

605 179 
 

EPA-2 527 192 
 

EPA-3 294 269 

 NASA-1 601 170 

 NASA-1a 730 264 

 NASA-2 659 269 

 NASA-3 676 212 

 NASA-4 583 282 

APEX-2 

 NASA-5 

T2 

647 

739

266 

265 


 

 T3 738 233 

APEX-3 

 T4 

T1 

518 

204 

233 

99 

 T2 647 501 

 T3 179 101 

 T4 172 138 

 T5 461 282 

 T6 802 440 

 T7 947 486 

 T8 563 448 

 T9 710 362 

 T10 301 126 

 T11 752 353 

Table 7-5. Test-Average Background Corrected CO2 Concentrations for Each Test 

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8. Particulate Matter Mass Emissions 

The PM-2.5 mass emissions were investigated by converting the PM number concentration data 

measured by the Nano-SMPS and EEPS into the PM mass concentrations assuming unit density and 

spherical morphology using Equations 5.18 and 5.19 The PM number concentration data measured by 

the ELPI were not used for this mass emission conversion because the ELPI measurements did not 

represent the entire particle size distribution and, without correct particle size distribution information, the 

mass concentrations could not be appropriately converted from the particle number concentration. Also 

note that the Nano-SMPS or EEPS were only operated in the plume sampling system of the DEAL. 

Therefore, for the Nano-SMPS, the ambient background was determined before and after each test and 

averaged to correct the data. The EEPS data were not background corrected since the background had 

been determined to have a negligible effect on the experimental results. 

From the PM-2.5 mass concentration, the mass emission index was calculated using the CO2 

concentration and carbon in the fuel according to Equation 5.12. The particle mass emission rate was 

then calculated by multiplying the mass emission index with the corresponding fuel flow rate using 

Equation 5.13. Thus, from the particle number concentrations corrected and uncorrected for line loss, the 

mass emission results before and after line loss corrections were calculated. The mass emission indices 

and emission rates obtained from the Nano-SMPS and EEPS are shown in Tables D-1 and D-2, 

respectively, in Appendix D. In this section, the Nano-SMPS was used as the primary instrument to 

determine EIM. 

The TEOM and QCM were also used in this study to directly monitor the PM mass emissions from the 

various jet engines. The TEOM was installed in both the plume and background sampling systems to 

allow for background correction in the calculation of the PM mass emission indices from measurements. 

The QCM was only employed in the plume monitoring, and therefore its results are not backgroundcorrected. The TEOM measurements were conducted for all three APEX campaigns. The QCM was only 

employed in the APEX-2 and APEX-3 campaigns. Due to the experimental difficulty of this study, the 

readings recorded by the TEOM and QCM were extremely unstable in some of the tests. Negative 

readings of PM mass concentration were recorded under some of the power conditions, and these tests 

showed very poor correlations between the measured PM mass concentrations and engine power (fuel 

flow rate). In the APEX-1 campaign, the TEOM measurements failed in all of the tests except NASA-2. In 

the APEX-3 campaign, TEOM measurements failed for tests T2, T3, T4, T8, and T9, and QCM 

measurements failed for tests T2, T4, T5, T8, and T9. Therefore, these data are not reported here. 

The data recorded by the TEOM and QCM were the mass concentrations for all sizes of particles. Since 

particle losses are particle size dependent, the correction of line particle losses for the data collected by 

these two instruments becomes difficult. To correct particle losses from the TEOM and QCM 

measurements, a particle loss correction coefficient was used. The particle loss coefficient is a ratio of the 

85
 

test-averaged particle mass concentration after line loss correction to the test-averaged concentration 

before line loss correction calculated from the Nano-SMPS measurements. The loss correction coefficient 

derived from Nano-SMPS data is assumed to apply equally well to TEOM and QCM data. Table 8-1 

presents the particle loss correction coefficient for each test in this study. 

Table 8-1. 	 Particle Loss Correction Coefficient Determined from Nano-SMPS Measurements for 

Each Test 

APEX Test 

Nano-SMPS Mass Concentration (mg/m3

) 

Before Loss Loss Correction Coefficient 

Correction 

After Loss 

Correction 

EPA-1 0.00620 0.00858 1.38 

EPA-2 0.0102 0.0142 1.40 

EPA-3 0.0103 0.0144 1.40 

NASA-1 0.0098 0.0132 1.35 

1 NASA-1a 0.0178 0.0240 1.35 

NASA-2 0.0135 0.0187 1.38 

NASA-3 0.0247 0.0355 1.44 

NASA-4 0.00918 0.0120 1.31 

NASA-5 0.0169 0.0226 1.34 

T1 0.00923 0.0104 1.12 

2 

T2 0.00877 0.00982 1.12 

T3 0.0154 0.0172 1.11 

T4 0.00851 0.00962 1.13 

T1 0.0251 0.0278 1.11 

T2 0.0908 0.0997 1.10 

T3 0.00496 0.00553 1.11 

T4 0.00434 0.00481 1.11 

T5 0.0822 0.0901 1.10 

3 T6 0.0389 0.0429 1.10 

T7 0.0522 0.0576 1.10 

T8 0.0406 0.0461 1.13 

T9 0.0407 0.0446 1.10 

T10 0.00692 0.00774 1.12 

T11 0.0592 0.0647 1.09 

The ratio for each test in the table is an average over the entire test and is assumed to be constant 

regardless of the variation of the engine power load. Therefore, the line loss correction for an uncorrected 

mass emission index measured for a certain power level of a jet engine was made by multiplying the 

mass emission index with a corresponding loss correction coefficient. The TEOM and QCM results before 

86 
and after sampling line particle loss correction, including the emission indices and emission rates under 

various power levels for different jet engines, are summarized in Tables D-3 and D-4, respectively, in 

Appendix D. 

Finally, the mass emission indices for different jet engines were determined on a test-average basis from 

the Teflon filter sampling. The gravimetric analysis of Teflon filters for the APEX-2 campaign failed, and 

results are not reported for that campaign. The PM mass emission index obtained from a filter sample 

was an average value over various engine power settings for an entire test. These test-average mass 

emission results will also be discussed in this section. 

The discussion of particle mass emissions will be based primarily on the measurement results made with 

the sampling probe located 30 m downstream of the tested engines. The effect of the probe position on 

the PM emissions will be discussed in Section 10. 

8.1 Effect of Fuel Flow Rate and Engine Thrust 

The mass emission index is expected to be correlated to the rated engine thrust as a function of fuel flow 

rate. Figure 8-1 shows the typical relationships between the particle mass emission index and the fuel 

flow rate obtained by the Nano-SMPS for the CFM56-2C1 engine powered with different jet fuels: base 

fuel (top left), high sulfur fuel (top right), and high aromatic fuel (bottom left). The data used in the graphs 

were obtained from the NASA-1a, NASA-2 and NASA-5 tests of the APEX-1 campaign, respectively. 

Figure 8-1 shows that the particle mass emission indices (EIM) under these test conditions ranged from 

~20 to 160 mg/kg. Unlike the particle number emission index, the value of EIM decreased when the fuel 

flow rate increased from around 300 kg/h. At 1000-2000 kg/h, the EIM reached the minimum and then 

increased with the fuel flow rate. Similar trends of the EIM with fuel flow rate for the CFM56-2C1 engine 

were also reported by other participants of the APEX-1 campaign (Anderson et al., 2006). Wey et al. 

(2006) reported that their line-loss-corrected mass-based emission indices derived from SMPS-type 

measurements for the APEX-1 campaign were typically 10 to 30 mg/kg in the low power ranges (less 

than 65%) and more than 200 mg/kg at climb and takeoff thrust. The EIM value first decreased as the 

power load increased from idle, and the value reached the lowest at the middle range of rated thrust, after 

which EIM increased with the power load. Lobo et al. (2006) reported from their APEX-1 measurements 

that the EIM values ranged from 1 to 370 mg/kg fuel, values which are close to what was obtained by EPA 

during the same tests. 

The PM particle mass emission indices for the CFM56-3B1 (T2 of APEX-2) and CFM56-7B24 (T4 of 

APEX-2) jet engines as derived from the Nano-SMPS are presented as a function of fuel flow rate in 

Figure 8-2. The figure shows a similar trend in the EIM of varying with the fuel flow rate for both engines. 

In general, the value of EIM always showed the minimum at mid-range fuel flow rates of 1000–1500 kg/h, 

corresponding to the operation of engines near approach power (30%). 

87
 

 

 

 

 

88
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


Figure 8-1. 	 PM-2.5 emission index as a function of fuel flow rate by Nano-SMPS for the 

CFM56-2C1 engine. Data shown are corrected for sampling line particle losses. 

0 

20 

40 

60 

80 

100 

120 

140 

160 

Emission Index (mg/kg fuel) 

CFM56-2C1 (APEX-1 NASA 1a)

Base Fuel 

0 

20 

40 

60 

80 

100 

120 

140 

160 

180 

Emission Index (mg/kg fuel) 

CFM56-2C1 (APEX-1 NASA 3)

High-Sulfur Fuel 

0 

50 

100 

150 

200 

250 

Emission Index (mg/kg fuel) 

CFM56-2C1 (APEX-1 NASA5)

High-Aromatic Fuel 
 

 

89
 


0 500 1000 1500 2000 2500
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000
 


Fuel Flow Rate (kg/h)
 


Figure 8-2. 	 PM-2.5 mass emission index as a function of fuel flow as determined by the NanoSMPS for: (a) APEX-2 T2; and (b) APEX-2 T4. Data corrected for sampling line loss. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

Emission Index (mg/kg fuel) 

CFM56-3B (APEX-2 T2) 

0 

10 

20 

30 

40 

50 

60 

70 

Emission Index (mg/kg fuel) 

CFM56-7B (APEX-2 T4) 
Figure 8-3 shows the particle mass emission indices as a function of fuel flow rate for the CJ610-8ATJ 

turbojet engine. The data were derived from the Nano-SMPS measurements from the 30-m probe in test 

T5 of the APEX-3 campaign. Like the results of particle number emissions discussed in Section 9.1 for 

this engine, the variation of the particle mass index with the fuel flow rate did not show the same pattern 

as that for the turbofan engines in this study. Figure 8-3 shows that, unlike the characteristic U-shaped 

curve, the EIM value monotonically increases with fuel flow rate. 

0 

100 

200 

300 

400 

500 

600 

700 

Emission Index (mg/kg fuel) 

CJ610-8ATJ (APEX-3 T5) 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


Figure 8-3. PM-2.5 mass emission index as a function of fuel flow rate as determined by the 

Nano-SMPS for the CJ610-8ATJ jet engine in APEX-3 T5. Data shown are corrected 

for sampling line particle losses. 

Test T10 from APEX-3 is the only test that conducted sampling at 30-m for the AE3007 series jet engine. 

Figure 8-4 presents the emission indices obtained from this 30-m sampling by the Nano-SMPS. The 

values of EIM derived from the measurements of the Nano-SMPS show a trend of the EIM with the engine 

load such that the value of EIM reached the minimum at fuel flow rates around 300 kg/h where the engine 

was operated in approach mode. 

The Nano-SMPS measurements during APEX-3 tests T6 and T7 for the P&W 4158 jet engine are 

presented in Figure 8-5. A trend similar to the CFM56 is shown with the values of EIM decreasing with an 

increase in engine load and reaching the minimum at fuel flow rates around 1000 to 2000 kg/h, after 

which the EIM increased with the fuel flow rate. 

The results for the RB211-535E4-B jet engine obtained from tests T8 and T9 from APEX-3 are shown in 

Figure 8-6 as derived from the Nano-SMPS measurements. There were no valid data available from the 

TEOM and QCM for this engine. The figure shows that the EIM of the RB211 varied with the fuel flow rate 

in a trend similar to that observed for the P&W 4158 engine below ~5000 kg/h. However, as the fuel flow 

rate increased above ~4,600 kg/h, the EIM for the RB211 started to decrease rather than to continuously 

increase as was seen for the P&W 4158 and the other turbofan engines tested. Note that the RB211 is an 

internally mixed-flow engine, unlike the P&W 4158 and CFM56. 

90
 
 

0 

20 

40 

60 

80 

100 

120 

140 

160 

Emission Index (particles/kg fuel) 

AE3007A1/1 (APEX-3 T10) 

0 500 1000 1500
 


Fuel Flow Rate (kg/h)
 


Figure 8-4. 	 PM-2.5 mass emission index as a function of fuel flow rate as determined by the 

Nano-SMPS for the AE3007A1/1 jet engine in APEX-3 T10. Data shown are corrected 

for sampling line particle losses. 

0 

50 

100 

150 

200 

250 

Emission Index (mg/kg fuel) 

P&W 4158 

APEX-3 T6 

APEX-3 T7 

0 1000 2000 3000 4000 5000 

Fuel Flow Rate (kg/h) 

6000 7000 8000 

Figure 8-5. PM-2.5 mass emission index as a function of fuel flow rate as determined by the 

Nano-SMPS for P&W 4158 jet engine in APEX-3 T6 and T7. Data shown are corrected 

for sampling line particle losses. 

91
 

 

0 

100 

200 

300 

400 

500 

600

Emission Index (mg/kg fuel) 

RB211-535E4-B 

APEX-3 T8 

APEX-3 T9 

0 1000 2000 3000 4000 

Fuel Flow Rate (kg/h) 

5000 6000 7000 

Figure 8-6. PM-2.5 mass emission index as a function of fuel flow rate as determined by the 

Nano-SMPS for RB211-535E4-B jet engine in APEX-3 T8 and T9. Data shown are 

corrected for sampling line particle losses. 

The particle mass emissions for the ICAO landing and take-off (LTO) thrust levels were also evaluated. 

Only four engine types had particle mass emission data collected at 30 m during all four ICAO-defined 

engine operating modes of idle (7%), takeoff (100%), climb (85%) and approach (30%). These four 

engines, tested during the APEX-3 campaign, were the CFM56-3B1, CJ610-8ATJ, AE3007A1/1 and 

RB211-535E4-B, which will be used as examples of the entire APEX data set. The lowest-rated thrust for 

the AE3007A1E engine was 8.4 percent, and the data collected under this rated thrust were used to 

represent the idle engine condition to compare with the other engines at 7 percent rated thrust. Although 

tests EPA-1, EPA-2, and EPA-3 from the APEX-1 campaign were specifically designed for investigating 

the ICAO engine cycle, the Nano-SMPS measurements for the takeoff and climb modes were inadequate 

for this analysis. Also, the four tests conducted during the APEX-2 campaign did not include 100 percent 

takeoff thrust. The average particle mass emission index results derived from the Nano-SMPS 

measurement under the four modes for these engines are summarized in Table 8-2. 

Figure 8-7 presents the average emission indices at the four power conditions for the CFM56-3B engine. 

As shown, the highest PM mass emissions were observed at takeoff power, followed by climb, idle, and 

approach, respectively. Thus the CFM56-3B engine had the best combustion efficiency when it was 

operated at approach power, and emitted the most PM-2.5 mass per kilogram of fuel at 100 percent 

takeoff power. 

92
 

Table 8-2. Effect of Engine Power on Average Emission Index for Different Engines 

Engine APEX-3 

Test Engine Cycle 

Emission Index 

Average SDa 

(mg/kg) (mg/kg) 

Idle (7%) 146 21.3 

CFM56-3B1 T11 

Takeoff (100%) 

Climb (85%) 

256 

215 

10.0 

8.21 

Approach (30%) 110 8.25 

Idle (7%) 6.28 1.128 

CJ610-8ATJ T5 

Takeoff (100%) 

Climb (85%) 

540 

441 

47.5 

37.3 

Approach (30%) 166 65.8 

Idle (8.4%) 64.4 55.4 

AE3007A1/1 T10 

Takeoff (100%) 

Climb (85%) 

57.3 

53.9 

2.89 

3.53 

Approach (30%) 30.2 3.63 

RB211-

535E4-B T9 

Idle (7%) 

Takeoff (100%) 

Climb (85%) 

Approach (30%) 

31.6 

67.1 

101 

60.7 

3.87 

2.18 

3.22 

4.34 

a

 SD = standard deviation. 

Idle (7%) Takeoff (100%) Climb (85%) Approach (30%) 

0 

50 

100 

150 

200 

250 

300 

Emission Index (mg/kg fuel) 

Figure 8-7. 	 Effect of engine operating mode on PM-2.5 mass emissions for a CFM56-3B1 engine. 

Based on Nano-SMPS loss corrected data. 

93
 

94 

For the CJ610-8ATJ turbojet engine, shown in Figure 8-8, the emission index was the highest at takeoff, 

similar to the CFM56-3B engine. The climb mode ranked the second, with the lowest value of EIM at idle. 

The mass emission indices for the internally mixed flow AE3007A1/1 engine tested in APEX-3 are shown 

in Figure 8-9. Unlike the other three engines, the AE3007A1/1 engine had the highest EIM value at idle. 

The EIM at takeoff ranked second and was the lowest under the approach mode. 

700 

600 

Emission Index (mg/kg fuel) 500 

400 

300 

200 

100 

0 

Idle (7%) Takeoff (100%) Climb (85%) Approach (30%) 

Figure 8-8. 	 Effect of engine operating mode on particle mass emissions for a CJ610-8ATJ 

turbojet engine. Based on Nano-SMPS loss-corrected data. 

140 

120 

Emission Index (mg/kg fuel) 100 

80 

60 

40 

20 

0 

Idle (8.4%) Takeoff (100%) Climb (85%) Approach (30%) 

Figure 8-9. 	 Effect of engine operating mode on particle mass emissions for an AE3007A1/1 

engine. Based on Nano-SMPS loss-corrected data. 
The PM mass emission index derived from the Nano-SMPS measurements for the RB211-535E4-B 

engine are presented in Figure 8-10. The emission index was the highest when the engine was operating 

at climb-out power, unlike the other three engines. This observation was also verified by the EEPS 

measurement results available for this test. In the order of their magnitude, climb > takeoff > approach > 

idle. 

0 

20 

40 

60 

80 

100 

120 

Emission Index (mg/kg fuel) 

Idle (7%) Takeoff (100%) Climb (85%) Approach (30%) 

Figure 8-10.	 Effect of engine operating mode on particle mass emissions for a RB211-535E4-B 

engine. Based on Nano-SMPS loss corrected data. 

8.2 Effect of Fuel Composition 

The effects of fuel composition on PM particle mass emission index were investigated based on the 

results obtained in the APEX-1 campaign. The average emission indices at individual power levels 

derived from the Nano-SMPS measurements are summarized in Table 8-3. The data were collected from 

three tests with different fuels: EPA-2 and NASA-1a using the base fuel, NASA-3 using the high-sulfur 

fuel, and NASA-4 using the high-aromatic fuel. 

Figure 8-11(a) compares the mass emission indices as a function of fuel flow rate between these different 

types of fuels. This figure shows that high-sulfur fuel emits more mass of particles per kg of fuel at all the 

tested power conditions. Like the particle number emissions, the high particle mass emissions from the 

high-sulfur fuel are believed attributable to the formation of additional sulfate particles. Although the base 

fuel showed slightly lower particle number emissions in comparison to the high-aromatic fuel, as will be 

discussed in Section 9, Figure 8-11(a) shows no obvious difference between these two fuels in terms of 

the particle mass emission index. 

To further illustrate the effect of fuel sulfur on the particle mass emissions, the particle mass emission 

indices obtained by the Nano-SMPS were plotted against the sulfur content in the fuel for idle and 

approach power as shown in Figure 8-11(b). The CFM56 jet engine results were used, including the data 

obtained from the -2C, -3B, and -7B models tested in the three APEX campaigns. The mass emission 

95
 

indices for the same level of engine rated thrust and the same sulfur content were averaged and 

presented in this figure. Although the Nano-SMPS data were only adequate for 7 and 30 percent power 

levels, all of the data show linear relationships between the mass emission index and the sulfur content in 

fuel. The particle mass emission index increased with the sulfur content. The linear equations and 

corresponding correlation coefficients are also shown in the figure. 

Table 8-3. 	 Comparison of Emission Indices by Different Type of Fuels (Based on Nano-SMPS 

particle loss-corrected results) 

Fuel Type Power 

(%) 

Fuel 

Flow 

Loss Corrected 

Emission Index 

(mg/kg Fuel) (kg/h) 

Average SD* 

4 336 108 24.6 

7 425 45.0 12.8 

30 1023 22.6 2.69 

Base Fuel 60 1922 26.6 2.47 

65 2088 32.2 1.21 

70 2252 36.9 1.11 

85 2904 70.2 3.39 

4 356 115 12.7 

7 403 108 8.33 

15 538 96.1 8.21 

High-Sulfur 

30 986 100 7.98 

40 1246 93.4 3.54 

60 1846 64.7 2.49 

65 2054 68.4 3.08 

85 2774 85.7 3.06 

4 344 53.0 16.7 

5.5 381 33.1 15.5 

7 401 33.3 5.60 

High-Aromatic 

30 962 23.6 0.941 

40 1218 21.7 1.11 

60 1850 19.9 0.402 

65 2019 23.6 1.37 

85 2700 59.4 2.66 

*SD = Standard Deviation 

96
 

 

 

 

 

 

Mass Emission Index (mg/kg fuel) 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

(a) Base Fuel (APEX-1 NASA 1a) 

High Sulfur Fuel (APEX-1 NASA 3) 

High Aromatic Fuel (APEX-1 NASA 4) 

0 500 1000 1500 2000 2500 3000 3500 

Fuel Flow Rate (kg/h) 

140 

120 

	 Emission Index (mg/kg fuel) 100 

80 

60 

40 

20 

0
 

7% Rated Thrust (b) 

30% Rated Thrust 

y = 0.0434x + 21.344 

R2 = 0.8818 

y = 0.0441x + 7.9311 

R2 = 0.9402 

0 200 400 600 800 1000 1200 1400 1600 1800
 


Sulfur Content in Fuel (ppm)
 


Figure 8-11.	 Effects of fuel type on: (a) mass emission index (CFM56-2C1) and (b) mass EI as a 

function of fuel sulfur (all CFM56 derivatives). Based on Nano-SMPS loss-corrected 

results. 

97
 

 

The effect of jet fuel sulfur content on particle mass emissions as discussed in this report is also 

consistent with the findings presented in the NASA APEX-1 report. Wey et al. (2006) reported that the 

high-sulfur fuel generated both more number and mass of particles in comparison to the other two types 

of fuel tested. A discussion of fuel sulfur conversion efficiency is provided in Section 13.1. 

8.3 Effect of Engine Type 

In Section 8.1, the effects of engine power on PM emission index were shown to depend on the type of 

engine studied. Different types of engines can have different relationships of EIM with power. For 

example, in the order of the particle number emission indices (see Section 9.1) for the CFM56-3B engine, 

approach is greater than idle which is greater than climb which, in turn, is greater than takeoff. This order 

is exactly the opposite of that obtained for the mass emission indices, indicating that the emitted particle 

sizes were different under the different engine operating modes. 

The effect of engine type on the particle mass emissions was investigated using the results derived from 

the Nano-SMPS measurements. The average mass emission indices obtained from the different types of 

engine tested are compared in Figure 8-12. The figure consist of plots representing the four ICAO LTO 

engine thrust modes of idle, take-off, climb and approach. All of the data were obtained with the base fuel 

or fleet fuel and were measured at the 30-m sampling location. In Figure 8-12, the emission indices of 

different engines are presented as bars with the average EIM value of each engine is written at the bottom 

of each bar. 

The data for tests EPA-1 and NASA-1 from APEX-1 and test T1 from APEX-3 were not used due to the 

consideration of possible background interference as discussed previously. The data were averages from 

the different tests of the same engines under each of the four engine operating modes during all three 

test campaigns. As indicated earlier, the lowest rated thrust for the AE3007A1E engine was 8.4 percent, 

which was used for the idle condition for comparison with the other engines at 7 percent rated thrust. For 

the P&W 4158 engine, the data available at 80 percent thrust were averaged and compared with the 

other engines under climb condition at 85 percent thrust. There were no data available at engine take-off 

(100% thrust) for the CFM56-2C, CFM56-7B and P&W 4158 engines. 

Because the fuel flow rate is related to both the engine rating and operating power, the fuel flow rates 

measured at the same power setting for the same engines were averaged and are also included in Figure 

8-12 as the second y-axis. The fuel flow rate data in the figure (pink points with values above them) 

indicate that the P&W 4158 and the Rolls-Royce RB211-535E4-B were two of the largest engines in this 

study. The CJ610-8ATJ turbojet and AE3007A1/1 engines were the smallest, and the CFM56 derivatives 

were mid-sized in terms of thrust and fuel flow rate (also see Table 2-1 for engine specifications). Note 

that the average fuel flow rates shown in Figure 8-12 for each thrust setting were obtained only from 

those test periods that also had valid Nano-SMPS measurements. Therefore, some of the fuel flow values 

shown in the figure may not match those presented previously in Table 7-2. 

A number of observations can be made from Figure 8-12. First, the smallest engine tested (CJ610-8ATJ 

turbojet) had the lowest EIM under 7 percent idle power, whereas the largest engine evaluated (P&W 

4158) exhibited the highest. The CJ610-8ATJ turbojet also displayed the largest EIM for 100 percent takeoff, 85 percent climb-out, and 30 percent approach, which is probably a function of its older combustor 

design. In addition, relatively good agreement in EIM was shown for the three CFM56 variants tested, with 

the exception of climb-out. In this case, the EIM varied over an order of magnitude for the three CFM56 

models tested. 

98
 
250
 800 700
 

700
 

600
 
 

538.42 58.97 

1226 1175 

Emission Index Fuel Flow Rate 

Take-Off (100%) 


 
 
 
 
 
 

44.96 34.98 25.55 4.14 64.86 171.25 77.97 

425 

401 

421 

227 

178 

532 

695 Emission Index 

Fuel Flow Rate 

Idle (7%)	 


 
 
 
 
 


 
 
 
 
 
 
 200
 600 

Emission Index (mg/kg fuel) Emission Index (mg/kg fuel) 500
 

500 

150
 400
 400
 

300
 100
 300
 200
 100
 

200
 100
 

50
 

0 0 0 

500
 

70.23 19.77 438.76 55.77 134.62 98.49 

2904 

4131 

1009 976 

7088 

6271 

Emission Index Fuel Flow Rate 

Climb (85%)	 


 
 
 
 
 
 
 
 
 

8000 250
 
 
 

22.64 24.55 18.34 163.44 33.24 27.76 

1023 

1158 

1101 

452 

371 

2298 

Emission Index Fuel Flow Rate 

Approach (30%)	 


 
 

450
 7000
 
 
 
 
 
 
 
 400
 200
 

6000
 350
 5000
 300
 150
 

250
 4000
 200
 100
 

3000
 150
 2000
 

100
 50
 

1000
 50
 

0 0 0 

CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 RB211 CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 

99
 


Figure 8-12. Effect of engine type on the PM-2.5 mass emission index for ICAO LTO power conditions. Based on t

Nano-SMPS results. 
8.4 	 Effect of Cold and Warm Engine Conditions 

The particle mass emission results obtained by Nano-SMPS were used to investigate the effect of engine 

operating temperature on the mass emission index. Recall that “cold” refers to going stepwise up in 

power, whereas “hot” is the opposite. In Figure 8-13, the particle mass emission indices obtained under 

the cold condition were plotted against the emission indices obtained under the warm operating condition 

measured by the Nano-SMPS for the same engine. The diagonal line in the figure represents where the 

emission indices under cold and warm conditions would be identical. 

The data obtained under the warm engine condition were linearly correlated with the data obtained for the 

cold condition. The correlation line had a slope of 0.92 with a correlation coefficient of 0.94. A slope less 

than one indicates that the engine had the higher efficiency and produced ~8 percent less PM mass at 

the warm condition than at the cold condition. Engine performance is expected to improve as it gets 

warmer. This trend is consistent with Lobo et al. (2007), and was also observed in terms of particle 

number, which will be discussed in Section 9. 

0 50 100 150 200 250 300 350 

EI under Cold Condition (mg/kg fuel) 

y = 0.92x 

R2 = 0.9388 

0 

50 

100 

150 

200 

250 

300 

350 

EI under Warm Condition (mg/kg fuel) 

Figure 8-13. Effect of cold and warm engine temperature on PM mass emission index. 

8.5 	 Comparison of Particle Mass Emission Indices Obtained from Different 

Instruments 

Since the ELPI could not produce appropriate particle size distributions for this jet engine study as 

discussed previously, the particle number emission data collected cannot be used to calculate the mass 

emission indices. The instruments that provided continuous mass emissions data were the Nano-SMPS, 

EEPS, TEOM and QCM. The EEPS was only used in the APEX-2 and APEX-3 campaigns. 

100
 

 

 

 

 

 

y = 3.8555x + 26.077 

R2 0.7365 

Figure 8-14 is the comparison between the measurement results by the Nano-SMPS and EEPS. Mass 

emission indices derived from the particle number concentrations collected by the two instruments 

correlate very well for tests T2, T3, T10, and T11 from APEX-3, with a correlation coefficient (r2

) greater 

than 0.93. The linear correlation between the Nano-SMPS and EEPS results was even better for tests T4 

and T5 from APEX-3 (r2

 = 0.97). However, the slope from the T4 and T5 tests was different from the slope 

for the other APEX-3 tests. A linear correlation between the mass emissions results of the two 

instruments for the four tests of APEX-2 was also observed, but with a relatively weak correlation 

coefficient (r2

 = 0.74). Figure 8-14 indicates that the EEPS had systematically higher measurement 

results than the Nano-SMPS in tests T1 to T4 from APEX-2 and tests T4 and T5 of APEX-3, but had 

lower measurements in T2, T3, T10, and T11 from APEX-3. The EEPS mass emission results for tests 

T6, T7, T8, and T9 during APEX-3 did not show linear correlations with the Nano-SMPS results, although 

their number emission results did. 

y = 0.6365x + 6.9964 

R2 = 0.9307 

y = 2.9906x + 186.24 

R2 = 0.9679 

= 

0 

500 

1000 

1500 

2000 

2500 

APEX-3 T2-T3 and T10-T11 

APEX-3 T4-T5 

APEX-2 T1-T4 

Emission Index by EEPS (mg/kg fuel) 

0 100 200 300 400 500 600 700
 


Emission Index by Nano SMPS (mg/kg fuel)
 


Figure 8-14. Comparison of the mass emissions indices between the Nano-SMPS and EEPS for 

different tests. 

The TEOM and QCM were used in the study to directly monitor the particle mass emissions. However, 

their data were unstable and were useful only for some of the tests. The linear correlations between the 

Nano-SMPS and the TEOM measurements of successful tests are presented in Figure 8-15. Figure 8-16 

shows the results from the Nano-SMPS with the successful QCM measurements. The lower correlation 

coefficients shown in these two figures indicate that the mass emissions data collected by TEOM and 

QCM were relatively scattered as compared to the number emissions data collected by the EEPS and 

ELPI (see Section 9). The higher slopes of the correlation lines in the figures mean that the 

measurements by TEOM and QCM were systematically higher than that obtained by Nano-SMPS in most 

of the cases in this study. 

101
 

 

 

 

 

y = 10.843x 84.615 

R2 0.6777 

y = 2.4676x + 146.05 

R2 0.6241 

y = 1.5691x + 58.245 

R2 = 0.6612 

y = 0.4114x + 365.14 

R2 = 0.835 

-

= 

= 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

1800 

APEX-3 T1,T6,T7,T10&T11 

APEX-3 T5 

APEX-2 T1-T4 

APEX-1 NASA2 

Emission Index by TEOM (mg/kg fuel) 

0 100 200 300 400 500 600 700 

Emission Index by Nano SMPS (mg/kg fuel) 

Figure 8-15. Comparison of the mass emissions indices between the Nano-SMPS and TEOM for 

different tests in APEX-2 and -3. 

102
 

y 14.227x 120.74 

R2 0.759 

y 12.05x 25.836 

R2 0.7727 

y 13.646x 167.52 

R2 0.846 

y 3.3389x + 220.44

R2 0.4504 

103
 


0 10 20 30 40 50 60 
 


Emission Index by Nano SMPS (mg/kg fuel)
 


0 50 100 150 200 250 300 350
 


Emission Index by Nano SMPS (mg/kg fuel)
 


Figure 8-16. Comparison of the mass emissions indices between the Nano-SMPS and QCM for: 

(a) APEX-2 tests and (b) APEX-3 tests. 

y = 11.569x - 169.72 

R2 = 0.821 

= -

= 

= -

=

 = -

= 

0 

100 

200 

300 

400 

500 

600 

700 

APEX-2, T1 

APEX-2, T4 

APEX-2, T2 

APEX-2, T3 

(a) 

Emission Index by QCM (mg/kg fuel) 

y = 3.9328x - 54.686 

R2 = 0.8173 

=

 = 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

APEX-3, T1, T11, T3, T6, T7 

APEX-3, T10 

(b) 

Emission Index by QCM (mg/kg fuel) 
 

 

 

 

Table 8-4 summarizes how well the different instruments performed during all APEX tests. The M in the 

table indicates acceptable measurements where the correlation coefficients between the measurements 

of the EEPS, TEOM and QCM instruments and the measurements obtained from the Nano-SMPS were 

above 0.5. The ( ” ) sign represents tests during which the particular instrument failed to track with engine 

power and the correlation coefficient was less than 0.3. 

Table 8-4. Comparison of Instruments Used for Mass Emissions Measurements 

Campaign Instrumentb 

APEX Test No. 

Airframe Engine Nano 

SMPS 

EEPS TEOM QCM 

EPA-1a M NA " NA 

EPA-2 M NA " NA 

NASA-1a

 M NA " NA 

NASA-1a M NA " NA 

1 EPA-3 DC-8 CFM56-2C1 M NA " NA 

NASA-2 M NA M NA 

NASA-3 M NA " NA 

NASA-4 M NA " NA 

NASA-5 M NA " NA 

T1 

B737-700 CFM56-7B24 

M M M M 

T4 M M M M 

2 

T2 CFM56-3B1 M M M M 

B737-300 

T3 CFM56-3B2 M M M M 

T1a 

B737-300 CFM56-3B1 

M M M M 

T11 M M M M 

T2 NASA Lear CJ610-8ATJ M M " " 

T5 Model 25 turbojet M M M " 

T3 

AE3007A1E 

M M " M 

3 T4 Embraer 

ERJ 145 M M " " 

T10 AE3007A1/1 M M M M 

T6 

A300 P&W 4158 

M " M M 

T7 M " M M 

T8 

B757 RB211-535E4-B 

M " " " 

T9 M " " " 

a.	 Test with high cross wind in the background. 

b.	 M = instrument measurements were acceptable. 

NA = not applicable. 

" = instrument’s measurements were not linearly correlated with the Nano-SMPS. 

104
 

8.6 Teflon Filter Integrated Sampling Results 

In this study, the Teflon filters were used to collect the PM-2.5 samples in both the plume and background 

sampling systems. However, the gravimetric analysis of the Teflon filters obtained from the APEX-2 

integrated sampling failed, and their results are not reported here. In APEX-1, integrated sampling was 

conducted for tests EPA-1, EPA-2, EPA-3, NASA-2&3, and NASA-4&5. The test called “NASA-2&3” 

represents the integrated sampling in which the same Teflon filters were used to collect samples during 

tests NASA-2 and NASA-3. The same qualification applies to NASA-4&5. For APEX-3, the tests 

conducting Teflon filter sampling included T3&4, T6&7, T9, and T11. All the Teflon filter data were 

background and line-loss corrected. The line-loss correction was done by using the loss correction 

coefficients obtained from the Nano-SMPS measurements as discussed previously. 

The PM mass emission index derived from the Teflon filter integrated sampling is an average value over 

the entire test including start-up, shut down and transitions. The percentage of volatile matter in the PM 

collected by a Teflon filter for each test was estimated by dividing the PM mass concentration from the 

filter after the thermal denuder by that from the plume filter. The mass emission indices thus obtained by 

the Teflon filters for various tests, together with the test-average EIM values derived from the 

measurements of other instruments, are summarized in Table 8-5. 

The table shows that almost the same PM mass emission indices were obtained from tests EPA-3 and 

NASA-2&3 with the same high sulfur fuel, although their engine operation was different. The timeweighted thrust level and fuel flow rate were 20.4 percent and 797 kg/h for EPA-3 and 38.5 percent and 

1278 kg/h for NASA-2&3, respectively. By averaging the results with the same fuels, the PM mass 

emissions and volatile contents for different fuels for the APEX-1 campaign were compared and are 

shown in Figure 8-17. The figure shows that the high sulfur fuel had the highest PM mass emission index 

and volatile fraction (79.3%) among the three types of fuels. This observation is generally consistent with 

the results obtained from the Nano-SMPS data. The volatile content in the PM emissions from the use of 

the base fuel and high-aromatic fuel ranged from ~62 to 66 percent. 

The test-average mass emission index obtained by filter sampling for the CFM56-2C engine fueled with 

base fuel is compared to the indices for the other engines in Figure 8-18. The figure shows that the large, 

internally mixed flow RB211-535E4-B engine produced the most mass of particles per kg of fuel and the 

smallest volatile fraction, while the smallest engine, the AE3007A1/1 (also internally mixed) had the 

lowest mass emission index. The PM emitted from all engines contained 40–80 percent volatile matter. 

The CFM56 engines appeared to emit more volatile matter (62–80%) compared to the others shown. 

Figure 8-19 compares the test-average emission indices derived from Teflon filter integrated sampling 

with the results derived from the Nano-SMPS measurements. The figure shows that the test average EI 

values were much higher from the Teflon filter sampling than from the Nano-SMPS measurements. The 

figure also shows that there was no linear correlation of results between two measurements. This lack of 

correlation is probably at least partially due to a slow instrument response time, which caused gaps in 

collecting sufficient data points for high thrust runs and transition from one thrust level to another in very 

short periods of time. Regardless of the cause, the large difference in EIM obtained by the Teflon filter 

sampling compared to traditional SMPS measurements certainly warrants further investigation. 

105
 

 

 

Table 8-5. Test-Average PM Mass Emission Indices Derived from Measurements of Various 

Instruments 

APEX Test 

Run 

Time Aircraft Engine Fuel 

Emission Index (mg/kg fuel) 

Teflon Filter 

NanoSMPS (min) EEPS TEOM QCM

Total % of 

Volatile 

EPA-1 188.53 * * * * * * 

EPA-2 150.7 

Base 

305 62.0 35.2 nc cc nc 

NASA-1 197.03 * * * * * * 

NASA-1a 112.3 nc - 54.8 nc cc nc 

1 EPA-3 149.58 DC-8 CFM56-2C1 447 69.3 42.0 nc cc nc 

NASA-2 116.98 HiSulfur 443 79.3 57.0 nc cc nc 

NASA-3 143.65 90.8 nc cc nc 

NASA-4 154.67 Hi- 219 65.5 31.2 nc cc nc 

NASA-5 155.5 Aromatic 59.4 nc cc nc 

T1 123.8 

B737-700 CFM56-7B24 gv - 34.4 132 262 89.9 

2 

T4 142.6 gv - 31.7 131 244 117 

T2 135.8 

B737-300 

CFM56-3B1 gv - 22.9 113 215 207 

T3 150.5 CFM56-3B2 gv - 39.6 167 272 326 

T1 115.6 

B737-300 CFM56-3B1 

* * * * * * 

T11 63.7 267 79.4 148 125 248 576 

T2 171.4 NASA Lear CJ610-8ATJ nc - 266 153 cc cc 

T5 146.1 Model 25 turbojet Fleet nc - 337 1221 532 cc 

T3 131.48 

AE3007A1E 116 61.8 

53.6 83.5 cc 172 

3 T4 112.43 Embraer 

EMB145 48.3 278 cc cc 

T10 96.75 AE3007A1/1 nc - 44.5 38.2 129 350 

T6 147.58 

A300 P&W 4158 268 53.6 

92.3 cc 178 cc 

T7 76.93 105 cc 243 cc 

T8 103.5 

B757 RB211-

535E4-B 384 40.9 

142 cc cc cc 

T9 122.43 109 cc cc cc 

* High background interference (crosswinds) during the test. 
 

nc Not collected. 
 

gv Gravimetric analysis of Teflon filters failed.
 

cc Poor correlation coefficient. 
 

106
 

0 

50 

100 

150 

200 

250 

300 

350 

400 

450 

500 

PM Mass Emission Index (mg/kg fuel) 

Volatile PM 

Non-Volatile PM 

62.0% 

79.3% 

65.5% 

305 

443 

219 

Base Fuel	 Hi-Sulfur Hi-Aromatic 

Figure 8-17.	 Effects of fuel type on test-average PM mass emission index from the Teflon filter for 

APEX-1 tests. Note that the percent volatile fraction is also shown in the figure. 

0 

50 

100 

150 

200 

250 

300 

350 

400 

450 

PM Mass Emission Index (mg/kg fuel) 

Volatile PM 

Non-Volatile PM 

62.0% 

79.4% 

53.6% 

305 

267 268 

61.8% 

116 

40.9% 

384 

CFM56-2C CFM56-3B AE3007A1E P&W 4158 RB211-535E4 

(APEX-1 EPA2) (APEX-3 T11) (APEX-3 T3&4) (APEX-3 T6&7) (APEX-3 T8&9) 

Figure 8-18.	 Effects of engine type on test-average PM mass emission index from the Teflon filter 

integrated sampling. Note that the percent volatile fraction is also shown in the 

figure. 

107
 
108
 


Test-Average Emission Index (mg/kg fuel) 

500
 

450
 

400
 

350
 

300
 

250
 

200
 

150
 

100
 

50
 

0 

Teflon Filter 

nano-SMPS 

EPA 2
 EPA 3
 NASA 2&3 NASA 4&5 T11 T3&4 T6&7 

APEX-1
 APEX-1
 APEX-1
 APEX-1
 APEX-3
 APEX-3
 APEX-3
 

Figure 8-19. Comparison of the test-average emission indices between Teflon filter and NanoSMPS measurements. 
9. PM Number Emissions 

The PSD measurements made by the Nano-SMPS, EEPS and ELPI provided the particle number 

concentrations under various test conditions. The PM number emissions in this study were quantified by 

emission index (EIN), which was expressed by the number of particles emitted from burning one kg of 

fuel. Although the ELPI was not useful in this study for the PSD determination due to the relatively large 

cut-off size of its lowest channel (see Section 10), the use of a filter stage enabled the instrument to 

measure the total particle number concentration for the jet engine PM emissions. Therefore, the PM 

number emissions data obtained from all three instruments are discussed in this section. 

The ELPI was installed in both the plume and background sampling systems to allow for background 

correction in the calculation of PM number emission indices. However, the Nano-SMPS and EEPS were 

only used in the plume sampling system. Therefore, the PM number emission indices obtained from the 

Nano-SMPS were corrected for background using data collected before/after each test. A similar 

correction was not applied to the EEPS, however, since background had little effect on the EIN values 

obtained. 

The PM particle number emission indices and their SDs under various test conditions, both before and 

after sampling line particle-loss correction, are summarized in Table E-1 for the Nano-SMPS, in Table E-2 

for the EEPS, and in Table E-3 for the ELPI as found in Appendix E. Note that the EEPS was not 

available during the APEX-1 campaign. In addition, the ELPI data were not available for some APEX-1 

tests (NASA-1 and NASA-5) and APEX-3 tests (T2, T5, T8 and T10) due to sample recovery. Thus, these 

results are not reported in the tables. Because of the effects of the crosswind on the emission 

measurements during tests EPA-1 and NASA-1 from APEX-1, and test T1 from APEX-3 (as indicated in 

Table 7-1), the emission results from these tests were not used in the particle emission analysis and are 

not presented in the tables. Note also that the ELPI is subject to small particle artifacts, thus further 

limiting its usefulness. 

It was difficult to run the jet engines under high power settings (e.g., 100% takeoff) for long periods of 

time. Therefore, few data points are available from the Nano-SMPS measurements at high power settings 

due to the slow instrument response. 

In this section, the effects of the fuel flow rate, fuel type, engine type, engine cycle, engine temperature, 

and sampling probe location were studied based on the particle number emissions results corrected for 

sampling line particle losses, except where noted. The discussion in the following subsections will 

primarily be based on the results obtained from the measurements made by the 30-m probe with the 

Nano-SMPS. 

109
 

 

9.1 Effect of Fuel Flow Rate 

The particle number emission indices from the jet engines were found to strongly correlate to the fuel flow 

rate, which in turn is a function of rated engine thrust. Figure 9-1 shows the typical relationship between 

the particle number emission index and the fuel flow rate observed by the Nano-SMPS for the CFM56-

2C1 engine burning three different jet fuels: base, high sulfur and high aromatic. The data used for these 

three fuels were obtained from the NASA-1a, NASA-2 and NASA-5 tests from the APEX-1 campaign, 

respectively. The average particle number emission indices range between 2×1015 to 8×1016 kg-1 with the 

value of EIN decreasing with increasing fuel flow rate. The decrease in particle number emission index 

was much steeper at a fuel flow rate <1000 kg/h. The emission indices were below 1×1016 particles/kg 

when the fuel flow rates were greater than approximately 2000 kg/h for the base fuel, 1000 kg/h for the 

high-sulfur fuel, and 2500 kg/h for the high-aromatic fuel. 

The above observation is consistent with the results reported in the NASA APEX-1 report for the 30-m 

probe (Wey et al., 2006). NASA found that the EIN values at 30 m were typically 5 to 20 times greater 

than in comparable samples drawn from the 1-m probe, with the EIN decreasing with increasing engine 

power. The EIN values obtained for the APEX-1 test ranged from 2×1015 to 4×1016 kg-1, which are close to 

the NASA results. NASA reported that the number-based emission indices varied from 1 to 5×1015 kg-1. 

Figure 9-2 presents the PM particle number emission indices as a function of fuel flow rate for the 

CFM56-3B1 and CFM56-7B24 engines. The CFM56-3B1 data are taken from the T2 test from APEX-2 

and the T11 test from APEX-3, whereas the CFM56-7B24 emission indices were obtained from the T4 

test from APEX-2. All models of the jet engine CFM56 show similar trends: the particle number emission 

index decreased with increases in fuel flow rate, except for the T11 test from APEX-3. In this case, the 

EIN increases slightly above idle, then decreases in a fashion similar to the other CFM56 engines tested. 

Note, however, that APEX-3 T11 only included the cold portion of the engine operating cycle which could 

have influenced these results. A steep reduction was also observed in the particle number emission index 

with fuel flow rates less than 500 kg/h. 

Figure 9-3 presents the particle number emission index as a function of fuel flow rate for the CJ610-8ATJ 

turbojet engine. This engine was evaluated in both the T2 and T5 tests from APEX-3. The emissions were 

sampled primarily by the 15-m probe, with only part of the data in the T5 test being measured by 30-m 

probe. Figure 9-3 shows the data for the T5 test as measured at the 30-m probe. These data do not 

follow the same trend that was observed for the CFM56 model engines shown above. This engine also 

exhibited a different trend in the EIM with fuel flow compared to the other engines which were previously 

described in Section 8. 

With the exception of engine CJ610-8ATJ, the relationship between the particle number emission index 

and the fuel flow rate for all the other types of engines tested in the three APEX campaigns was similar to 

the relationship observed for the CFM56 engines. For example, the results from the APEX-3 campaign for 

the AE3007 series engines are presented in Figure 9-4, the P&W4158 engine in Figure 9-5, and the 

RB211-535E4-B engine in Figure 9-6. 

110
 

111
 


 

 

 

0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0.0E+00 

5.0E+15 

1.0E+16 

1.5E+16 

2.0E+16 

2.5E+16 

3.0E+16 

3.5E+16 

4.0E+16 

Emission Index (particles/kg fuel) 

CFM56-2C1 

(APEX-1 NASA 1a)

Base Fuel 

(a) 

0.0E+00 

2.0E+16 

4.0E+16 

6.0E+16 

8.0E+16 

1.0E+17 

1.2E+17 

Emission Index (particles/kg fuel) 

CFM56-2C1 

(APEX-1 NASA 2)

High-Sulfur Fuel 

(b) 

0.0E+00 

1.0E+16 

2.0E+16 

3.0E+16 

4.0E+16 

5.0E+16 

6.0E+16 

7.0E+16 

8.0E+16 

Emission Index (particles/kg fuel) 

CFM56-2C1 

(APEX-1 NASA5)

High-Aromatic Fuel 

(c) 

Figure 9-1. 	 Particle number emission indices as a function of fuel flow as determined by the 

Nano-SMPS during APEX-1 for: (a) base fuel; (b) high-sulfur fuel; and (c) higharomatic fuel. 
Emission Index (particles/kg fuel) Emission Index (particles/kg fuel) Emission Index (particles/kg fuel) 

7.0E+15 

6.0E+15 

5.0E+15 

4.0E+15 

3.0E+15 

2.0E+15 

1.0E+15 

0.0E+00 

9.0E+15 

8.0E+15 

7.0E+15 

6.0E+15 

5.0E+15 

4.0E+15 

3.0E+15 

2.0E+15 

1.0E+15 

0.0E+00 

(a) CFM56-3B1 (APEX-2 T2) 

0 500 1000 1500 2000 2500 

Fuel Flow Rate (kg/h) 

CFM56-3B1 (APEX-3 T11) (b) 

0 500 1000 1500 2000 2500 3000 3500 4000 

Fuel Flow Rate (kg/h) 

1.6E+16
 


1.4E+16
 


1.2E+16
 


1.0E+16
 


8.0E+15
 


6.0E+15
 


4.0E+15
 


2.0E+15
 


0.0E+00
 


(c) CFM56-7B24 (APEX-2 T4) 

0 500 1000 1500 2000 2500 3000
 


Fuel Flow Rate (kg/h)
 


Figure 9-2. 	 Particle number emission indices as a function of fuel flow as determined by the 

Nano-SMPS for two CFM56 engine models during: (a) APEX-2 T2; (b) APEX-3 T11; 

and (c) APEX-2 T4. Data shown are corrected for line losses. 

112
 
0.0E+00 

2.0E+15 

4.0E+15 

6.0E+15 

8.0E+15 

1.0E+16 

1.2E+16 

1.4E+16 

1.6E+16 

Emission Index (particles/kg fuel) 

CJ610-8ATJ (APEX-3 T5) 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

Figure 9-3. 	 Particle number emission index as a function of fuel flow rate as determined by the 

Nano-SMPS for the CJ10-8ATJ turbojet engine. Data shown are corrected for 

sampling line particle losses. 

113
 

0.0E+00 

5.0E+15 

1.0E+16 

1.5E+16 

2.0E+16 

2.5E+16 

3.0E+16 

3.5E+16 

4.0E+16 

Emission Index (particles/kg fuel) 

AE3007A1E (APEX-3 T3) 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

7.0E+16 

Emission Index (particles/kg fuel) 6.0E+16 

5.0E+16 

4.0E+16 

3.0E+16 

2.0E+16 

1.0E+16 

0.0E+00 

0 500 1000 1500 

AE3007A1/1 (APEX-3 T10) 

Fuel Flow Rate (kg/h) 

Figure 9-4. 	 Particle number emission index as a function of fuel flow as determined by the NanoSMPS for: AE3007A1E; and AE3007A1/1 engines. Data are corrected for particle line 

losses. 

114 
115
 

 

2.5E+16 

2.0E+16 

1.5E+16 

1.0E+16 

5.0E+15 

0.0E+00 

2.5E+16 

2.0E+16 

1.5E+16 

1.0E+16 

5.0E+15 

0.0E+00 

Emission Index (particles/kg fuel) Emission Index (particles/kg fuel) 

P&W 4158 (APEX-3 T6) 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Fuel Flow Rate (kg/h) 

P&W 4158 (APEX-3 T7) 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Fuel Flow Rate (kg/h) 

Figure 9-5. Particle number emission index as a function of fuel flow as determined by the NanoSMPS for a PW4158 engine during: Test 6; and Test 7 of APEX-3. Data are corrected 

for particle line losses. 
 

 

Emission Index (particles/kg fuel) 

3.0E+16 

2.5E+16 

2.0E+16 

1.5E+16 

1.0E+16 

5.0E+15 

0.0E+00 

RB211-535E4-B (APEX-3 T8) 

0 1000 2000 3000 4000 5000 6000 7000 

Fuel Flow Rate (kg/h) 

4.0E+16
 

3.5E+16 	 Emission Index (particles/kg fuel) 

RB211-535E4-B (APEX-3 T9) 

3.0E+16
 

2.5E+16
 

2.0E+16
 

1.5E+16
 

1.0E+16
 

5.0E+15
 

0.0E+00
 

0 1000 2000 3000 4000 5000 6000 7000 8000
 

Fuel Flow Rate (kg/h)
 

Figure 9-6. 	 Particle number emission index as a function of fuel flow as determined by the NanoSMPS for two different RB211-535E4B engines during: Test 8; and Test 9 of APEX-3. 

Data are corrected for particle line losses. 

116
 
 

 

y -1E+16ln(x) + 9E+16 

R2 0.7209 

y 2E+15ln(x) + 2E+16 

R2 0.935 

y -1E+16ln(x) + 8E+16 

R2 0.9245 

A predictive model was found capable of approximately describing the relationship between the particle 

number emission index and the fuel flow rate obtained in this study. Figure 9-7 is an example of the 

results obtained from the EEPS measurements, showing that, in general, the emission indices obtained 

for five types of engines were logarithmically correlated to the fuel flow rate (power). 

y = -3E+16ln(x) + 2E+17 

R2 = 0.9723 

y = -2E+16ln(x) + 2E+17 

R2 = 0.918 

=

 =

 = ­

=

 =

 = 

0.0E+00 

2.0E+16 

4.0E+16 

6.0E+16 

8.0E+16 

1.0E+17 

1.2E+17 

CFM56-7B 

CFM56-3B 

AE3007A1/1 

P&W 4158 

RB211 

Emission Index (#/kg fuel) 

100 1000 10000 

Fuel Flow Rate (kg/h) 

Figure 9-7. 	 Logarithmic correlation between particle number emission index measured by EEPS 

and fuel flow rate. 

9.2 Effect of Fuel Composition 

The effects of fuel composition on the PM particle number emission index were investigated based on the 

results of the Nano-SMPS and ELPI obtained in the APEX-1 campaign. Figure 9-8 compares the 

emission indices as a function of fuel flow rate obtained from the three tests with different fuels: test 

NASA-1a with the base fuel, test NASA-3 with the high-sulfur fuel, and test NASA-4 with the higharomatic fuel. 

The Nano-SMPS results in Figure 9-8 show that high-sulfur fuel produced higher particle counts at all 

tested fuel flow rates. The higher particle number emissions from the high-sulfur fuel may be attributable 

to the formation of sulfate particles or sulfate coatings on particles. A small portion of the sulfur in jet fuel 

was converted into sulfuric acid. The sulfuric acid could either form nucleates or condense onto the 

existing aerosol surfaces as the plume cooled. Sulfur content in the PM and its contribution will be further 

discussed in Sections 10 and 13. 

117
 
 

0.0E+00 

5.0E+15 

1.0E+16 

1.5E+16 

2.0E+16 

2.5E+16 

3.0E+16 

3.5E+16 

4.0E+16 

4.5E+16 

5.0E+16 

Emission Index (particles/kg fuel) 

Base Fuel (NASA 1a) 

HIgh-Sulfur NASA 3 

High-Aromatics NASA 4 

0 500 1000 1500 2000 2500 3000 3500 

Fuel Flow Rate (kg/h) 

Figure 9-8. 	 Effects of fuel type on particle number emissions index as determined during 

APEX-1 (Nano-SMPS). 

Figure 9-8 also shows that the base fuel had the lowest particle number emissions in comparison with the 

other fuel types tested. The slightly higher particle number emissions observed from the high-aromatic 

fuel over the base fuel can also be attributed to a combination of a slight increase in sulfur content (553 

ppm for the high-aromatic fuel and 409 ppm for the base fuel) as well as the higher aromatic content of 

the fuel tested. These trends are also consistent with those reported previously by other APEX-1 

investigators (Wey et al., 2006). 

Anderson et al. (2006) found that the values of particle number emission index varied in rough proportion 

to fuel sulfur content, with values at any given power setting following the trend that high sulfur fuel > high 

aromatic fuel > base JP8 fuel. Petzold and Schroder (1998) also found from their jet engine exhaust 

aerosol study that the SO2 emitted from a jet engine was oxidized by OH or O to SO3, which then reacted 

with H2O to form gaseous H2SO4. Nucleation and condensation of the low volatility sulfuric acid and 

hydrocarbons were the primary sources for the increase in number of particles in the exhaust plume. 

To further illustrate the effect of fuel sulfur on the particle number emissions, the Nano-SMPS particle 

number emission indices obtained with fuels of same sulfur content for the CFM56 series engine 

(including models -2C1, -3B1 and 2 and -7B24 used in APEX-1 and APEX-2 campaigns) were averaged 

under two levels of engine thrust: 7 and 30 percent. The results were then plotted as a function of fuel 

118
 

 

sulfur content as shown in Figure 9-9. The figure shows that the particle number emission index 

increased with fuel sulfur. However, the emission indices at 132 ppm sulfur were higher than those at 206 

and 352 ppm sulfur. The reason for this observation is not currently known. One possible explanation is 

associated with differences in technology used in the three variants of the CFM56 jet engine used in this 

comparison. The CFM56-7B24 engine was tested with the fuel of 132 ppm sulfur, while the CFM56-3B 

engine used the fuels with 206 ppm and 352 ppm sulfur. The CFM56-3B seemed to produce a smaller 

number of particles. 

 

Emission Index (particles/kg fuel) 

7.0E+16 

6.0E+16 

5.0E+16 

4.0E+16 

3.0E+16 

2.0E+16 

1.0E+16 

0.0E+00 

0 200 400 600 800 1000 1200 1400 1600 1800 

Sulfur Content in Fuel (ppm) 

7% Rated Thrust 

30% Rated Thrust 

Figure 9-9. Particle number emission index as a function of fuel sulfur for all CFM56 variants. 

9.3 Effect of Engine Type 

To investigate the effect of engine type on the particle number emissions, only the data obtained with the 

base fuel or fleet fuel measured at 30 m were used. Considering the possible interference of strong 

crosswinds, the results for the tests EPA-1 and NASA-1 from APEX-1, and test T1 from APEX-3, were 

discarded. For comparison, the particle number emission indices obtained by the same jet engines in 

different tests were averaged under the four engine power settings that simulate the ICAO airport LTO 

cycle. 

The lowest rated thrust for the tests with jet engine AE3007A1E was 8.4 percent, and this value was 

treated as the idle engine condition and compared with the other engines at 7 percent thrust. Similar 

treatment was used for the P&W 4158 engine, where data at 80 percent thrust were averaged and 

119
 

compared with the other engines under climb-out condition (85% thrust). The fuel flow rates 

corresponding to each engine power setting were also averaged to obtain the averaged fuel flow rate 

under that engine cycle for each different engine. 

The results of averaged EIN values for different engines as a function of fuel flow rates are compared in 

Figure 9-10. These results indicate that, in general, the P&W4158 had the highest particle number 

emission index. Since the value of EIN is also engine-power-dependent, the comparison of particle 

number emission index between different engines was made under the same engine operation mode. 

Table 9-1 and Figure 9-11 show the comparisons of the EIN values obtained by the Nano-SMPS for 

different engines at the four designated LTO engine power settings (idle, takeoff, climb and approach). 

The data at engine takeoff mode were not available for the CFM56-2C1, CFM56-7B24 and P&W 4158 

engines. The data show that, at engine takeoff and climb modes, the CJ610-8ATJ turbojet produced the 

highest particle number emissions per kg of fuel burned among the seven engines shown. The reason for 

the low emissions for the CJ610-8ATJ turbojet engine at idle is unknown. It seems unlikely that this 

discrepancy was attributable primarily to the measurement errors, because this trend was also shown by 

the EIN results derived from the EEPS measurement, as shown in Figure 9-12. 

It is also interesting to note from Figure 9-11 that, among the CFM56 engine variants, the EIN at climb-out 

power for model -7B was significantly lower than the comparable value for the older technology -2C and 

-3B models (also see Lobo et al., 2007). At idle and approach, however, the model -3B had the lowest 

EIN, followed by -7B, and -2C models, respectively. 

9.4 Effect of Cold and Warm Engine Conditions 

The particle number emission results derived from the Nano-SMPS measurements were used to 

investigate the effect of engine cold and warm operating conditions on the particle number emission 

index. In Figure 9-13, the particle number emission indices obtained under the cold engine condition were 

plotted against the emission indices obtained for the same engines under the warm operating condition. 

The diagonal line in the figure represents the situation where the emission index results obtained under 

cold and warm conditions are identical. The linear regression results are also provided in the figure (see 

the pink line) showing a slope of 0.92. This slope would indicate that the PM number emission indices are 

approximately 8 percent lower with warm engines. 

120
 

0 2000 4000 6000 8000 

Fuel Flow Rate (kg/h) 

0.0E+00 

5.0E+15 

1.0E+16 

1.5E+16 

2.0E+16 

2.5E+16 

3.0E+16 

3.5E+16 

4.0E+16 

4.5E+16 

Particle Number Emission Index (particles/kg fuel) 

CFM56-2C1 

CFM56-7B24 

CFM56-3B 

CJ610-8ATJ 

AE3007A1/1 

P&W 4158 

RB211-535E4B 

 

 

 

 

Figure 9-10.	 Particle number emission index as a function of fuel flow (power) for different 

engines (Nano-SMPS). 

Table 9-1. 	 Particle Number Emission Indices at Each of Four Engine Power Settings for 

Different Engines (Nano-SMPS results) 

Engine 

Idle Takeoff Climb Approach 

Ave SD Ave SD Ave SD Ave SD 

CFM56-2C1 2.02E+16 2.40E+15 6.79E+15 3.24E+14 1.44E+16 1.89E+15 

CFM56-7B24 1.11E+16 1.18E+15 9.56E+14 3.38E+13 7.70E+15 1.21E+15 

CFM56-3B 5.20E+15 6.53E+14 3.58E+15 1.40E+14 4.40E+15 1.68E+14 3.98E+15 4.34E+14 

CJ610-8ATJ 2.03E+14 1.48E+14 1.01E+16 1.41E+15 9.76E+15 5.53E+14 1.32E+16 7.28E+14 

AE3007A1/1 2.64E+16 1.56E+16 6.45E+15 3.37E+14 7.45E+15 5.03E+14 9.79E+15 1.59E+15 

P&W 4158 2.00E+16 1.79E+15 2.45E+15 2.77E+14 1.03E+16 4.37E+14 

RB211-535E4-B 1.25E+16 8.51E+14 7.59E+14 2.46E+13 1.41E+15 6.33E+13 4.80E+15 4.37E+14 

Ave = arithmetic average; SD = standard deviation. 

121
 

122
 


4.5E+16 4.0E+16 

1.4E+16 1.2E+16 

Particle Number Emission Index (particles/kg fuel) Particle Number Emission Index (particles/kg fuel) 3.5E+16 3.0E+16 2.5E+16 2.0E+16 1.5E+16 1.0E+16 5.0E+15 0.0E+00 Idle 1.2E+16 1.0E+16 8.0E+15 6.0E+15 4.0E+15 2.0E+15 0.0E+00 Climb 

Particle Number Emission Index (particles/kg fuel) Particle Number Emission Index (particles/kg fuel) 1.0E+16 8.0E+15 6.0E+15 4.0E+15 2.0E+15 0.0E+00 T

1.8E+16 1.6E+16 1.4E+16 1.2E+16 1.0E+16 8.0E+15 6.0E+15 4.0E+15 2.0E+15 0.0E+00 App

Figure 9-11. Comparison of particle number emission indices for different engines at: idle; take-off; climb-out; an

(Nano-SMPS). 
y

0.0E+00 

2.0E+16 

4.0E+16 

6.0E+16 

8.0E+16 

1.0E+17 

1.2E+17 

Emission Index (#/kg fuel) 

CFM56-7BCFM56-3B

CJ610-8ATJ

AE3007A1/1

P&W 4158

RB211 

Figure 9-12. Comparison of particle number emission indices by EEPS for different engines 

under the idle power condition. 

 = 0.9207x 

R2 = 0.96 

0.0E+00 

1.0E+16 

2.0E+16 

3.0E+16 

4.0E+16 

EI under Warm Condition (particles/kg fuel) 

0.0E+00 1.0E+16 2.0E+16 3.0E+16 4.0E+16 

EI under Cold Condition (particles/kg fuel) 

Figure 9-13. Effect of engine operating temperature on particle number emission index. 

123
 

 

 

 

 

 

124
 

9.5 	 Comparison of Particle Number Emission Indices Obtained from Different 

Instruments 

Four different instruments were used in the APEX campaigns for the measurement of particle number 

concentration in the plume. The Nano-SMPS was used for plume sampling during all three APEX 

campaigns, a SMPS equipped with a long DMA for both plume and background sampling during APEX-1, 

an EEPS for plume sampling during APEX-2 and APEX-3, and an ELPI for both plume and background 

sampling during all three APEX campaigns. 

The comparison between Nano-SMPS and EEPS was made based on the test results obtained from the 

APEX-2 and APEX-3 campaigns. The EIN results obtained by the EEPS were plotted against the data 

obtained with the Nano-SMPS under the same test conditions. The two straight lines shown in Figure 9-

14 were obtained, indicating a linear relationship between the Nano-SMPS and EEPS measurements. 

These lines represent the two groups of APEX tests: (1) APEX-3: T1-T3 and T6-T11, and (2) APEX-3: T4- 

T5 and APEX-2: T1-T4. It is not clear why the results obtained by Nano-SMPS and EEPS were linearly 

correlated in the separate groups, as this observation could not be explained by engine type or test 

conditions. The explanation may be related either to the characteristics of the PM emissions, differences 

in instrument design, or both. 

y = 1.2868x - 2E+15 

R2 = 0.6782 

y = 7.8933x + 4E+15 

R2 = 0.9018 

APEX-3 T1-T3 and T6-T11 

APEX-3 T4-T5 and APEX-2 T1-T4 

0.0E+00 1.0E+16 2.0E+16 3.0E+16 4.0E+16
 

Emission Index by Nano SMPS (particles/kgfuel) 

Figure 9-14. Comparison of particle number emission indices as obtained from the Nano-SMPS 

and EEPS instruments. 

Emission Index by EEPS (particles/kg fuel) 

1.6E+17 

1.4E+17 

1.2E+17 

1.0E+17 

8.0E+16 

6.0E+16 

4.0E+16 

2.0E+16 

0.0E+00 
The EIN results from APEX-1, obtained by the long DMA SMPS, were compared with those obtained by 

Nano-SMPS in Figure 9-15. The figure shows that measurements from two instruments can be correlated 

approximately in two linear groups: (1) tests EPA-1, EPA-2, NASA-1, NASA-1a, NASA-2, NASA-3 and 

EPA-3; and (2) NASA-4 and NASA-5. This observation again suggests that the characteristics of the PM 

might affect the comparison of instrument measurements since the group (1) data were obtained with 

base jet fuel or high sulfur fuel, and group (2) data were from the high aromatic fuel. Both lines in the 

figure have slope values of less than 0.7, probably due to the difference in the effect of line loss correction 

on the results from these two instruments. The long DMA SMPS did not collect particles smaller than 

10 nm, so the line losses of the particles in the 3 to 10 nm size range were counted by the Nano-SMPS 

but were not compensated for by the long DMA SMPS. 

 

3.5E+16 

APEX-1 EPA 1-3 and NASA 1-3
 


APEX-1 NASA 4-5
 


3.0E+16 

2.5E+16 

y = 0.6348x - 4E+14 

R2 = 0.9121 

2.0E+16 

1.5E+16 

y = 0.4942x - 2E+15 

1.0E+16 R2 = 0.747 

5.0E+15
 


0.0E+00
 


Emission Index by Nano SMPS (particles/kg fuel)
 


Emission Index by SMPS (particles/kgfuel) 

0.0E+00 1.0E+16 2.0E+16 3.0E+16 4.0E+16
 


Figure 9-15. Comparison of particle number emission indices as obtained from the Nano-SMPS 

and long DMA SMPS. 

125
 

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126
 

10. Particle Size Distribution and Geometric Mean Diameter 

The PM emissions from jet engines were monitored by various instruments for investigations of the 

effects of fuel type, fuel flow rate, engine type and operating condition (cold or warm) on particle size 

distribution (PSD). In APEX-1, the PM PSDs were measured with a long DMA SMPS, the Nano-SMPS, 

and the ELPI. PM emitted from the jet engines contained a large portion of particles with diameters below 

the sizes of the lowest instrument channel for either the long DMA SMPS or the ELPI. Only the NanoSMPS was capable of providing a complete PSD for the jet engine PM emissions. However, the NanoSMPS had a data recording frequency of approximately 2.5 minutes. In contrast, the engine run time for 

the 100 percent power setting was usually maintained for less than 1.5 minutes. This relatively slow 

instrument response made it difficult for the Nano-SMPS to obtain the PSD information under the highest 

power settings. Therefore, no PSDs for the 100 percent power setting (take-off) are reported for NanoSMPS, and limited data are reported for the 85 percent power setting (climb). After the APEX-1 

campaign, an EEPS was used to replace the long DMA SMPS for PM emissions measurements in both 

APEX-2 and APEX-3. The EEPS had a fast instrument response and was able to record data points at 1 

second intervals. 

The differential number PSD, dN/dlogDp at a specified power setting, was obtained by averaging the 

particle numbers recorded under the same engine operating condition from the same instrument size bins 

and then plotting them against the particle size. Both the Nano-SMPS and EEPS were only used in the 

plume emissions measurement system. Therefore, the PM emission results obtained by the Nano-SMPS 

were background-corrected using measurements obtained before and after each test. No background 

correction was needed for the EEPS, as discussed earlier. Also, the PSD data both before and after 

particle line loss-correction are presented in the following discussion with the differences also 

investigated. 

The geometric mean diameter (GMD) and geometric standard deviation (GSD) were calculated as a 

function of fuel flow rate from the PSD for each individual test of the three APEX campaigns. Table F-1, 

included in Appendix F, summarizes the results obtained from the Nano-SMPS and EEPS 

measurements. The GMD and GSD data, both before and after particle loss correction, are presented in 

the table. 

10.1 Particle Size Results for APEX-1 

During APEX-1, all tests were conducted on a CFM56-2C1 engine using two different engine testing 

matrices. The “EPA” test matrix followed the ICAO-defined LTO cycle to simulate aircraft emissions at an 

airport and consisted of approximately four repetitions of the following power settings: 26 min at idle (7%), 

0.7 min at takeoff (100%), 2.2 min at climb (85%), and 4 min at approach (30%). The “NASA” test matrix 

was designed to investigate the effects of engine operating parameters on particle emissions and 

encompassed steady-state power settings of 4, 5.5, 7, 15, 30, 40, 60, 65, 70, 85 and 100 percent 

127
 

 

(restricted to about 93% actual thrust, henceforth, 100%). Except for the 100 percent thrust level, which 

was limited to a run-time of 1.5 min, approximately 10 min were provided at each power setting to allow 

for samples to be adequately analyzed. 

The PSD at a specified experimental condition was obtained by averaging the dN/dlogDp data recorded 

from the instrument in the same size bins and then plotting those averages against the particle size. To 

investigate the effects of fuel type and engine operation cycle on PSD, the dN/dlogDp data were then 

averaged for the same fuel type and operation cycle. Since only the Nano-SMPS was able to cover the 

entire particle size range of the jet engine PM emissions, this section is restricted to the results obtained 

from the Nano-SMPS measurements. Also, no PSD data for the 100 percent power setting (as well as the 

85% power setting for EPA-2) are reported here as discussed above. 

The particle size results for the EPA test series conducted during APEX-1 are shown in Figures 10-1 to 

10-3. Note that both the loss-corrected (a) and uncorrected (b) PSDs are provided in these figures. 

Figures 10-4 to 10-9 provide similar information for the NASA test series. The figures show that for most 

tests a unimodal and log-nomal PSD was obtained regardless of experimental conditions. 

10.2 Particle Size Results for APEX-2 

During the APEX-2 campaign, two additional models of the CFM56 engine, the -7B24 and -3B1 and 2, 

were tested. The engine-rated power thrust was varied in a stepwise fashion at six thrust levels (4, 7, 30, 

40, 65, and 85%) as discussed in Section 6. Except for the 85 percent thrust level where run-time was 8 

min, approximately 10 min were provided at each power setting to allow for samples to be adequately 

analyzed. The power setting was first increased from the lowest thrust level to highest level under cold 

engine conditions, and then decreased under warm engine conditions to investigate the effects of engine 

temperature on particle emissions. 

Figures 10-10, 10-11, 10-12 and 10-13 present the average PSDs under different power settings obtained 

from the Nano-SMPS, with (a) and without (b) particle loss correction for tests T1, T2, T3 and T4, 

respectively. Again these figures show that the PSDs of the PM emissions from jet engines were 

generally unimodal and followed a log-normal function. 

10.3 Particle Size Results for APEX-3 

In APEX-3 campaign, six different engines were tested for emissions at various power settings. Like 

APEX-2, the engine tests in APEX-3 were conducted by increasing the thrust power in a stepwise fashion 

from idle (4 or 7%) to climb (100%) under cold engine conditions and then decreasing through the same 

power settings under warm engine conditions. 

Figures 10-14 to 10-24 present the Nano-SMPS results of the average PSD with (a) and without (b) 

particle loss correction under different power settings for each of individual tests T1 through T11, 

respectively. All the data were measured with the 30 m sampling probe. The PSDs shown in these figures 

were log-normal and consistent with the results of APEX-1 and APEX-2. However, in some cases, the 

PSDs were bimodal with an additional accumulation mode present at higher fuel flows. 

128
 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

436 kg fuel/h Loss Corr 

992 kg fuel/h Loss Corr 

2819 kg fuel/h Loss Corr 

(a) 

1 10 100 

Particle Diameter (nm)
 

6.0E+06
 

4.0E+06 

2.0E+06 

0.0E+00
 

1 10 100 

Particle Diameter (nm)
 

436 kg fuel/h 

992 kg fuel/h 

2819 kg fuel/h 

(b) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

 

Figure 10-1. Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-1, (a) with line 

loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 2969 kg fuel/h (100%) power. 

129
 

 

 

dN/dlogDp (1/cm3) 

1.6E+07
 

1.4E+07
 

1.2E+07
 

1.0E+07
 

8.0E+06
 

6.0E+06
 

4.0E+06
 

2.0E+06
 

0.0E+00
 

425 kg fuel/h Loss Corr 

1023 kg fuel/h Loss Corr 

(a) 

1 10 100

Particle Diameter (nm) 

1.6E+07
 

1.4E+07
 

	 dN/dlogDp (1/cm3)

1.2E+07
 

1.0E+07
 

8.0E+06
 

6.0E+06
 

4.0E+06
 

2.0E+06
 

0.0E+00
 

425 kg fuel/h 

1023 kg fuel/h 

(b) 

1 10 100

Particle Diameter (nm) 

 

Figure 10-2.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-2, (a) with line 

loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 2860 kg fuel/h (85%) and 3181 kg fuel/h (100%) power. 

130
 

 

 

 

 

dN/dlogDp (1/cm3) 

3.5E+07
 

3.0E+07
 

2.5E+07
 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

438 kg fuel/h Loss Corr 

964 kg fuel/h Loss Corr 

2424 kg fuel/h Loss Corr 

2840 kg fuel/h Loss Corr 

(a) 

1 10 100

Particle Diameter (nm)
 

3.5E+07
 

3.0E+07
 	 dN/dlogDp (1/cm3) 

2.5E+07
 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

438 kg fuel/h 

964 kg fuel/h 

2424 kg fuel/h 

2840 kg fuel/h 

(b) 

1 10 100

Particle Diameter (nm)
 

Figure 10-3.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test EPA-3, (a) with line 

loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 3116 kg fuel/h (100%) power. 

131
 

dN/dlogDp (1/cm3) 

1.6E+07 

1.4E+07 

1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

350 kg fuel/h Loss Corr 

386 kg fuel/h Loss Corr 

427 kg fuel/h Loss Corr 

560 kg fuel/h Loss Corr 

1012 kg fuel/h Loss Corr 

1252 kg fuel/h Loss Corr 

1998 kg fuel/h Loss Corr 

2406 kg fuel/h Loss Corr 

(a) 

1 10 100

Particle Diamter (nm) 

1.6E+07
 

1.4E+07
 	 dN/dlogDp (1/cm3)

1.2E+07
 

1.0E+07
 

8.0E+06
 

6.0E+06
 

4.0E+06
 

2.0E+06
 

0.0E+00
 

350 kg fuel/h 

386 kg fuel/h 

427 kg fuel/h 

560 kg fuel/h 

1012 kg fuel/h 

1252 kg fuel/h 

1998 kg fuel/h 

2406 kg fuel/h 

(b) 

1 10 100

Particle Diamter (nm) 

 

Figure 10-4.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-1, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 2906 kg fuel/h (100%) power. 

132
 

2.0E+07 

1.8E+07 

1.6E+07 

1.4E+07 

1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

336 kg fuel/h Loss Corr 

1922 kg fuel/h Loss Corr 

2098 kg fuel/h Loss Corr 

2252 kg fuel/h Loss Corr 

2898 kg fuel/h Loss Corr 

(a) 

dN/dlogDp (1/cm3) 

1 10 100 

Particle Diameter (nm) 

2.0E+07
 

1.8E+07
 
 336 kg fuel/h 

1922 kg fuel/h 

2098 kg fuel/h 

2252 kg fuel/h 

2898 kg fuel/h 

(b) 

	 
 dN/dlogDp (1/cm3)

1.6E+07
 


1.4E+07
 

1.2E+07
 

1.0E+07
 

8.0E+06
 

6.0E+06
 

4.0E+06
 

2.0E+06
 

0.0E+00
 

1 10 100 

Particle Diameter (nm) 

 

Figure 10-5.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-1a, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 3127 kg fuel/h (100%) power. 

133
 

 

 

 

 

 

 

 

 

dN/dlogDp (1/cm3) 

3.0E+07
 

2.5E+07
 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

345 kg fuel/h Loss Corr 

413 kg fuel/h Loss Corr 

543 kg fuel/h Loss Corr 

955 kg fuel/h Loss Corr 

1235 kg fuel/h Loss Corr 

1855 kg fuel/h Loss Corr 

2046 kg fuel/h Loss Corr 

2727 kg fuel/h Loss Corr 

(a) 

1	 	 10 100 

Particle Diameter (nm) 

3.0E+07
 

2.5E+07
 	 dN/dlogDp (1/cm3) 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

345 kg fuel/h 

413 kg fuel/h 

543 kg fuel/h 

955 kg fuel/h 

1235 kg fuel/h 

1855 kg fuel/h 

2046 kg fuel/h 

2727 kg fuel/h 

(b) 

1	 	 10 100 

Particle Diameter (nm) 

 

Figure 10-6.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-2, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 3116 kg fuel/h (100%) power. 

134
 

 

 

 

 

4.0E+07 

3.5E+07 

3.0E+07 

2.5E+07 

2.0E+07 

1.5E+07 

1.0E+07 

5.0E+06 

0.0E+00 

347 kg fuel/h Loss Corr 

405 kg fuel/h Loss Corr 

538 kg fuel/h Loss Corr 

986 kg fuel/h Loss Corr 

1255 kg fuel/h Loss Corr 

2053 kg fuel/h Loss Corr 

2758 kg fuel/h Loss Corr 

(a) 

dN/dlogDp (1/cm3) 

1 10 100 

Particle Diameter (nm) 

4.0E+07
 

3.5E+07
 

	 

347 kg fuel/h 

405 kg fuel/h 

538 kg fuel/h 

986 kg fuel/h 

1255 kg fuel/h 

2053 kg fuel/h 

2758 kg fuel/h 

(b) 

dN/dlogDp (1/cm3)

3.0E+07
 

2.5E+07
 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

1 10 100 

Particle Diameter (nm) 

 

Figure 10-7.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-3, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 3051 kg fuel/h (100%) power. 

135
 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 2.5E+07 

2.0E+07 

1.5E+07 

1.0E+07 

5.0E+06 

0.0E+00 

1 

345 kg fuel/h Loss Corr 

381 kg fuel/h Loss Corr 

401 kg fuel/h Loss Corr 

960 kg fuel/h Loss Corr 

1220 kg fuel/h Loss Corr 

2023 kg fuel/h Loss Corr 

2157 kg fuel/h Loss Corr 

2708 kg fuel/h Loss Corr 

(a) 

10 100 

Particle Diameter (nm) 

2.5E+07 

2.0E+07 

1.5E+07 

1.0E+07 

5.0E+06 

0.0E+00 

1 10 100 

Particle Diameter (nm) 

345 kg fuel/h 

381 kg fuel/h 

401 kg fuel/h 

960 kg fuel/h 

1220 kg fuel/h 

2023 kg fuel/h 

2157 kg fuel/h 

2708 kg fuel/h 

(b) 

 

Figure 10-8. Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-4, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 2978 kg fuel/h (100%) power. 

136
 

dN/dlogDp (1/cm3) 

3.0E+07
 

2.5E+07
 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

345 kg fuel/h Loss Corr 

410 kg fuel/h Loss Corr 

989 kg fuel/h Loss Corr 

1292 kg fuel/h Loss Corr 

2131 kg fuel/h Loss Corr 

2894 kg fuel/h Loss Corr 

(a) 

1	 10 100 

Particle Diamter (nm)
 

3.0E+07
 

2.5E+07
 	 dN/dlogDp (1/cm3) 

2.0E+07
 

1.5E+07
 

1.0E+07
 

5.0E+06
 

0.0E+00
 

345 kg fuel/h 

410 kg fuel/h 

989 kg fuel/h 

1292 kg fuel/h 

2131 kg fuel/h 

2894 kg fuel/h 

(b) 

1	 	 10 100 

Particle Diamter (nm) 

 

Figure 10-9.	 	 Average PSD measured by the Nano-SMPS during APEX-1, Test NASA-5, (a) with 

line loss correction; and (b) without line loss correction. 

Note: unable to collect PSD for 3176 kg fuel/h (100%) power. 

137
 

1.0E+07 

Cold 336 kg fuel/h Loss Corr (a) Cold 418 kg fuel/h Loss Corr 

Cold 1180 kg fuel/h Loss Corr 

8.0E+06 Cold 1544 kg fuel/h Loss Corr 

Cold 2497 kg fuel/h Loss Corr 

Cold 4131 kg fuel/h Loss Corr 

Warm 2497 kg fuel/h Loss Corr 6.0E+06 

Warm 1498 kg fuel/h Loss Corr 

Warm 1135 kg fuel/h Loss Corr 

Warm 313 kg fuel/h Loss Corr 4.0E+06 

2.0E+06 

0.0E+00 

1 10 100 

Particle Diameter (nm) 

1.0E+07 

Cold 336 kg fuel/h (b) 

Cold 418 kg fuel/h 

Cold 1180 kg fuel/h 

8.0E+06 Cold 1544 kg fuel/h 

Cold 2497 kg fuel/h 

Cold 4131 kg fuel/h 

6.0E+06 Warm 2497 kg fuel/h 

Warm 1498 kg fuel/h 

Warm 1135 kg fuel/h 

Warm 313 kg fuel/h 4.0E+06 

2.0E+06 

0.0E+00 

1 10

Particle Diameter (nm)
 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

1
 
 00 

Figure 10-10. Average PSD for a CFM56-7B24 engine measured by the Nano-SMPS during 

APEX-2, Test T1, (a) with line loss correction; and (b) without line loss correction. 

138
6.0E+06 

Cold 2700 kg fuel/h Loss Corr (a) Cold 3348 kg fuel/h Loss Corr
 

Cold 8712 kg fuel/h Loss Corr 5.0E+06 

Cold 11124 kg fuel/h Loss Corr
 

dN/dlogDp (1/cm3)

Cold 17388 kg fuel/h Loss Corr
 

4.0E+06	 	 Warm 17316 kg fuel/h Loss Corr
 

Warm 10836 kg fuel/h Loss Corr
 

Warm 8460 kg fuel/h Loss Corr
 

3.0E+06	 	 Warm 3312 kg fuel/h Loss Corr
 

Warm 2736 kg fuel/h Loss Corr
 

2.0E+06 

1.0E+06 

0.0E+00
 

1 10 100
 

Particle Diameter (nm)
 

6.0E+06 

Cold 2700 kg fuel/h (b) Cold 3348 kg fuel/h
 


Cold 8712 kg fuel/h

 5.0E+06 

Cold 11124 kg fuel/h
 

	 
 dN/dlogDp (1/cm3)

Cold 17388 kg fuel/h
 

4.0E+06	 	 Warm 17316 kg fuel/h
 

Warm 10836 kg fuel/h
 

Warm 8460 kg fuel/h
 

3.0E+06	 	 Warm 3312 kg fuel/h
 

Warm 2736 kg fuel/h
 

2.0E+06 

1.0E+06 

0.0E+00 

1 10 100 

Particle Diameter (nm) 

Figure 10-11. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during APEX-2, 

Test T2, (a) with line loss correction; and (b) without line loss correction. 

139
dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

7.0E+06 

6.0E+06 

5.0E+06 

4.0E+06 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00 

7.0E+06 

6.0E+06 

5.0E+06 

4.0E+06 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00 

Cold 2952 kg fuel/h Loss Corr 

Cold 3492 kg fuel/h Loss Corr 

Cold 8964 kg fuel/h Loss Corr 

Cold 11448 kg fuel/h Loss Corr 

Cold 17856 kg fuel/h Loss Corr 

Warm 17928 kg fuel/h Loss Corr 

Warm 11196 kg fuel/h Loss Corr 

Warm 8784 kg fuel/h Loss Corr 

Warm 3348 kg fuel/h Loss Corr 

Warm 2916 kg fuel/h Loss Corr 

1 10

1 

Particle Diameter (nm) 

Cold 2952 kg fuel/h 

Cold 3492 kg fuel/h 

Cold 8964 kg fuel/h 

Cold 11448 kg fuel/h 

Cold 17856 kg fuel/h 

Warm 17928 kg fuel/h 

Warm 11196 kg fuel/h 

Warm 8784 kg fuel/h 

Warm 3348 kg fuel/h 

Warm 2916 kg fuel/h 

10 

Particle Diameter (nm) 

(a) 

(b) 

100 

100 

Figure 10-12. Average PSD for a CFM56-3B2 engine measured by the Nano-SMPS during APEX-2, 

Test T3, (a) with line loss correction; and (b) without line loss correction. 

140
9.0E+06 Cold 2664 kg fuel/h Loss Corr (a) Cold 3312 kg fuel/h Loss Corr 

8.0E+06 Cold 9360 kg fuel/h Loss Corr 

Cold 12240 kg fuel/h Loss Corr 

7.0E+06 Cold 19800 kg fuel/h Loss Corr 

dN/dlogDp (1/cm3) 

6.0E+06 

5.0E+06 

4.0E+06 

Warm 19800 kg fuel/h Loss Corr 

Warm 11880 kg fuel/h Loss Corr 

Warm 9000 kg fuel/h Loss Corr 

Warm 3024 kg fuel/h Loss Corr 

Warm 2484 kg fuel/h Loss Corr 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00 

1 10

Particle Diameter (nm) 

9.0E+06 

8.0E+06 

7.0E+06 

6.0E+06 

5.0E+06	 

4.0E+06 

Cold 2664 kg fuel/h
 

Cold 3312 kg fuel/h 

Cold 9360 kg fuel/h
 

Cold 12240 kg fuel/h
 

Cold 19800 kg fuel/h
 

Warm 19800 kg fuel/h
 

Warm 11880 kg fuel/h
 

Warm 9000 kg fuel/h
 

Warm 3024 kg fuel/h
 

Warm 2484 kg fuel/h
 

(b)
 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00
 

1 10
 

Particle Diameter (nm) 

100 

	 
 dN/dlogDp (1/cm3) 

100 

Figure 10-13. Average PSD for a CFM56-7B24 engine measured by the Nano-SMPS during 

APEX-2, Test T4, (a) with line loss correction; and (b) without line loss correction. 

141 
1.0E+07 

8.0E+06 

Cold 300 kg fuel/h Loss Corr 

Cold 397 kg fuel/h Loss Corr 

Cold 654 kg fuel/h Loss Corr 

Cold 1136 kg fuel/h Loss Corr 

Cold 1618 kg fuel/h Loss Corr 

(a) 

dN/dlogDp (1/cm3) 6.0E+06	 

4.0E+06	 

2.0E+06	 

Cold 2260 kg fuel/h Loss Corr 

Cold 2903 kg fuel/h Loss Corr 

Cold 3385 kg fuel/h Loss Corr
 

Warm 3385 kg fuel/h Loss Corr
 

Warm 2903 kg fuel/h Loss Corr
 

Ward 2260 kg fuel/h Loss Corr
 

Warm 1618 kg fuel/h Loss Corr
 

Warm 1136 kg fuel/h Loss Corr
 

Warm 654 kg fuel/h Loss Corr
 

Warm 397 kg fuel/h Loss Corr
 

Warm 300 kg fuel/h Loss Corr 

0.0E+00
 

1 10

Particle Diameter (nm)
 

1.0E+07 

8.0E+06 

6.0E+06	 

4.0E+06	 

2.0E+06	 

Cold 300 kg fuel/h 

Cold 397 kg fuel/h
 

Cold 654 kg fuel/h
 

Cold 1136 kg fuel/h
 

Cold 1618 kg fuel/h
 

Cold 2260 kg fuel/h
 

Cold 2903 kg fuel/h
 

Cold 3385 kg fuel/h
 

Warm 3385 kg fuel/h
 

Warm 2903 kg fuel/h
 

Ward 2260 kg fuel/h
 

Warm 1618 kg fuel/h
 

Warm 1136 kg fuel/h
 

Warm 654 kg fuel/h
 

Warm 397 kg fuel/h
 

Warm 300 kg fuel/h 

(b) 

0.0E+00 

1 10 100 

Particle Diameter (nm) 

	 
 dN/dlogDp (1/cm3) 

100 

Figure 10-14. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during APEX-3, 

Test T1, (a) with line loss correction; and (b) without line loss correction. 

142
1.8E+07 Cold 182 kg fuel/h Loss Corr
 


Cold 304 kg fuel/h Loss Corr (a)
 1.6E+07 Cold 452 kg fuel/h Loss Corr
 


Cold 568 kg fuel/h Loss Corr 1.4E+07 Cold 760 kg fuel/h Loss Corr
 


Cold 999 kg fuel/h Loss Corr 1.2E+07 Cold 1226 kg fuel/h Loss Corr
 


Warm 1226 kg fuel/h Loss Corr

 1.0E+07 

Ward 763 kg fuel/h Loss Corr
 


Warm 568 kg fuel/h Loss Corr

 8.0E+06 

Warm 454 kg fuel/h Loss Corr
 


Warm 304 kg fuel/h Loss Corr

 6.0E+06 

Warm 182 kg fuel/h Loss Corr
 


4.0E+06
 


2.0E+06 

0.0E+00
 


1 10 100
 


Particle Diameter (nm)
 


1.8E+07 Cold 182 kg fuel/h 

(b) Cold 304 kg fuel/h 1.6E+07 Cold 452 kg fuel/h
 


Cold 568 kg fuel/h

 1.4E+07 

Cold 760 kg fuel/h
 


Cold 999 kg fuel/h

 1.2E+07 

Cold 1226 kg fuel/h
 


Warm 1226 kg fuel/h

 1.0E+07 

Ward 763 kg fuel/h
 


Warm 568 kg fuel/h

 8.0E+06 

Warm 454 kg fuel/h
 


Warm 304 kg fuel/h

 6.0E+06 

Warm 182 kg fuel/h
 


4.0E+06
 


2.0E+06 

0.0E+00
 


1 10
 
 100 

Particle Diameter (nm) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

Figure 10-15. Average PSD for a CJ610-8ATJ turbojet engine measured by the Nano-SMPS during 

APEX-3, Test T2, (a) with line loss correction; and (b) without line loss correction. 

143
5.0E+06 

Cold 174 kg fuel/h Loss Corr (a) Cold 238 kg fuel/h Loss Corr 

Cold 389 kg fuel/h Loss Corr 

Cold 555 kg fuel/h Loss Corr 4.0E+06 

Cold 805 kg fuel/h Loss Corr 

dN/dlogDp (1/cm3)

Cold 1082 kg fuel/h Loss Corr 

Cold 1286 kg fuel/h Loss Corr 

3.0E+06 Warm 1088 kg fuel/h Loss Corr 

Ward 810 kg fuel/h Loss Corr 

Warm 563 kg fuel/h Loss Corr 

Warm 392 kg fuel/h Loss Corr 

2.0E+06	 Warm 235 kg fuel/h Loss Corr
 

Warm 173 kg fuel/h Loss Corr
 

1.0E+06 

0.0E+00
 

1 10

Particle Diameter (nm)
 

5.0E+06 Cold 174 kg fuel/h (b) Cold 238 kg fuel/h 

Cold 389 kg fuel/h 

Cold 555 kg fuel/h 4.0E+06 

	 
 Cold 805 kg fuel/h dN/dlogDp (1/cm3) 3.0E+06	 

2.0E+06	 

Cold 1082 kg fuel/h 

Cold 1286 kg fuel/h 

Warm 1088 kg fuel/h
 

Ward 810 kg fuel/h
 

Warm 563 kg fuel/h
 

Warm 392 kg fuel/h
 

Warm 235 kg fuel/h
 

Warm 173 kg fuel/h
 

1.0E+06 

0.0E+00 

1 10

Particle Diameter (nm) 

100 

100 

Figure 10-16. Average PSD for an AE3007-A1E engine measured by the Nano-SMPS during 

APEX-3, Test T3, (a) with line loss correction; and (b) without line loss correction. 

144
5.0E+06 

Cold 168 kg fuel/h Loss Corr 

(a)	 Cold 239 kg fuel/h Loss Corr 

Cold 385 kg fuel/h Loss Corr 

Cold 547 kg fuel/h Loss Corr 4.0E+06 

Cold 788 kg fuel/h Loss Corr 

Cold 1050 kg fuel/h Loss Corr 

Cold 1253 kg fuel/h Loss Corr 

Warm 1052 kg fuel/h Loss Corr 3.0E+06 

Warm 786 kg fuel/h Loss Corr 

Warm 549 kg fuel/h Loss Corr 

Warm 384 kg fuel/h Loss Corr 

Warm 231 kg fuel/h Loss Corr 2.0E+06 

Warm 167 kg fuel/h Loss Corr 

1.0E+06 

0.0E+00
 


1 10

Particle Diameter (nm)
 


5.0E+06 

Cold 168 kg fuel/h 

(b)	 Cold 239 kg fuel/h 

Cold 385 kg fuel/h 

Cold 547 kg fuel/h 4.0E+06 

Cold 788 kg fuel/h 

Cold 1050 kg fuel/h 

Cold 1253 kg fuel/h 

Warm 1052 kg fuel/h 3.0E+06 

Warm 786 kg fuel/h 

Warm 549 kg fuel/h 

Warm 384 kg fuel/h 

Warm 231 kg fuel/h 2.0E+06 

Warm 167 kg fuel/h 

1.0E+06 

0.0E+00
 


1 10
 
 100 

Particle Diameter (nm) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

100 

Figure 10-17. Average PSD for an AE3007-A1E engine measured by the Nano-SMPS during 

APEX-3, Test T4, (a) with line loss correction; and (b) without line loss correction. 

145 

 


 

1.2E+07 Cold 227 kg fuel/h Loss Corr 

Cold 303 kg fuel/h Loss Corr 

Cold 452 kg fuel/h Loss Corr 

1.0E+07 Cold 567 kg fuel/h Loss Corr 

Cold 763 kg fuel/h Loss Corr 

Cold 1009 kg fuel/h Loss Corr
 

8.0E+06 Cold 1226 kg fuel/h Loss Corr
 


Warm 1226 kg fuel/h Loss Corr
 


Warm 1009 kg fuel/h Loss Corr
 


6.0E+06 Warm 763 kg fuel/h Loss Corr
 

Warm 567 kg fuel/h Loss Corr
 

Warm 452 kg fuel/h Loss Corr
 

4.0E+06 Warm 227 kg fuel/h Loss Corr 

2.0E+06 

0.0E+00
 

1 10 

Particle Diameter (nm)
 

1.2E+07 Cold 227 kg fuel/h 

Cold 303 kg fuel/h 

Cold 452 kg fuel/h 

1.0E+07 Cold 567 kg fuel/h 

Cold 763 kg fuel/h 

Cold 1009 kg fuel/h 

8.0E+06 Cold 1226 kg fuel/h 

Warm 1226 kg fuel/h 

Warm 1009 kg fuel/h 

6.0E+06 Warm 763 kg fuel/h 

Warm 567 kg fuel/h 

Warm 452 kg fuel/h 

4.0E+06 Warm 227 kg fuel/h 

2.0E+06 

0.0E+00
 

1 10
 

Particle Diameter (nm) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

(a) 

100
 

(b) 

100 

Figure 10-18. Average PSD for a CJ610-8ATJ turbojet engine measured by the Nano-SMPS during 

APEX-3, Test T5, (a) with line loss correction; and (b) without line loss correction. 

146 
1.8E+07 Cold 610 kg fuel/h Loss Corr (a) 

Cold 1014 kg fuel/h Loss Corr 1.6E+07 Cold 2245 kg fuel/h Loss Corr
 


Cold 3726 kg fuel/h Loss Corr



1.4E+07 Cold 5827 kg fuel/h Loss Corr
 


Cold 7026 kg fuel/h Loss Corr
 


1.2E+07 Warm 7026 kg fuel/h Loss Corr
 


Warm 5658 kg fuel/h Loss Corr
 


1.0E+07 Warm 3834 kg fuel/h Loss Corr
 


Warm 2465 kg fuel/h Loss Corr
 


8.0E+06 Warm 1097 kg fuel/h Loss Corr
 


Warm 368 kg fuel/h Loss Corr
 


6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00
 


1 10 100
 


Particle Diameter (nm)
 


1.8E+07 Cold 610 kg fuel/h (b) 

Cold 1014 kg fuel/h 1.6E+07 Cold 2245 kg fuel/h
 


Cold 3726 kg fuel/h



1.4E+07 Cold 5827 kg fuel/h
 


Cold 7026 kg fuel/h
 


1.2E+07 Warm 7026 kg fuel/h
 


Warm 5658 kg fuel/h
 


1.0E+07 Warm 3834 kg fuel/h
 


Warm 2465 kg fuel/h
 


8.0E+06 Warm 1097 kg fuel/h
 


Warm 368 kg fuel/h
 


6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00
 


1 10
 
 100 

Particle Diameter (nm) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

Figure 10-19. Average PSD for a PW4158 engine measured by the Nano-SMPS during APEX-3, 

Test T6, (a) with line loss correction; and (b) without line loss correction. 

147 
2.0E+07 

1.8E+07 

1.6E+07 

1.4E+07 

1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

2.0E+07 

1.8E+07 

1.6E+07 

1.4E+07 

1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

Cold 600 kg fuel/h Loss Corr (a) 

Cold 1035 kg fuel/h Loss Corr 

Cold 2230 kg fuel/h Loss Corr 

Cold 3688 kg fuel/h Loss Corr 

Cold 5702 kg fuel/h Loss Corr 

Cold 7100 kg fuel/h Loss Corr 

Warm 7200 kg fuel/h Loss Corr 

Warm 5711 kg fuel/h Loss Corr 

Warm 2252 kg fuel/h Loss Corr 

Warm 596 kg fuel/h Loss Corr 

1 10

Particle Diameter (nm) 

Cold 600 kg fuel/h 

Cold 1035 kg fuel/h 

Cold 2230 kg fuel/h 

Cold 3688 kg fuel/h 

Cold 5702 kg fuel/h 

Cold 7100 kg fuel/h 

Warm 7200 kg fuel/h 

Warm 5711 kg fuel/h 

Warm 2252 kg fuel/h 

Warm 596 kg fuel/h 

(b) 

1 10

Particle Diameter (nm) 

100 

100 

Figure 10-20. Average PSD for a PW4158 engine measured by the Nano-SMPS during APEX-3, 

Test T7, (a) with line loss correction; and (b) without line loss correction. 

148
1.2E+07 Cold 566 kg fuel/h Loss Corr (a) Cold 770 kg fuel/h Loss Corr
 

Cold 1191 kg fuel/h Loss Corr
 

1.0E+07	 	 Cold 2109 kg fuel/h Loss Corr
 


Cold 3178 kg fuel/h Loss Corr
 


dN/dlogDp (1/cm3)

Cold 4750 kg fuel/h Loss Corr
 

8.0E+06	 	 Cold 6096 kg fuel/h Loss Corr
 

Warm 4691 kg fuel/h Loss Corr
 

Warm 3436 kg fuel/h Loss Corr
 

Warm 2131 kg fuel/h Loss Corr 6.0E+06 

Warm 1178 kg fuel/h Loss Corr
 


Warm 654 kg fuel/h Loss Corr
 


Warm 437 kg fuel/h Loss Corr



4.0E+06 

2.0E+06 

0.0E+00
 

1 10 100
 

Particle Diameter (nm)
 

1.2E+07 Cold 566 kg fuel/h (b) Cold 770 kg fuel/h 

Cold 1191 kg fuel/h 1.0E+07 Cold 2109 kg fuel/h
 

Cold 3178 kg fuel/h 	 dN/dlogDp (1/cm3)

Cold 4750 kg fuel/h
 

8.0E+06	 	 Cold 6096 kg fuel/h
 

Warm 4691 kg fuel/h
 

Warm 3436 kg fuel/h
 

6.0E+06	 	 Warm 2131 kg fuel/h
 

Warm 1178 kg fuel/h
 

Warm 654 kg fuel/h
 

4.0E+06	 	 Warm 437 kg fuel/h 

2.0E+06 

0.0E+00
 

1 10
 100 

Particle Diameter (nm) 

Figure 10-21. Average PSD for a RB211-535E4B engine measured by the Nano-SMPS during 

APEX-3, Test T8, (a) with line loss correction; and (b) without line loss correction. 

149 
1.4E+07 

Cold 421 kg fuel/h Loss Corr 

Cold 690 kg fuel/h Loss Corr (a) 

Cold 1221 kg fuel/h Loss Corr 1.2E+07 

Cold 2004 kg fuel/h Loss Corr
 


Cold 3068 kg fuel/h Loss Corr
 


Cold 4479 kg fuel/h Loss Corr

 1.0E+07 Cold 6233 kg fuel/h Loss Corr
 

Cold 6966 kg fuel/h Loss Corr
 

Warm 6307 kg fuel/h Loss Corr 8.0E+06 Warm 4551 kg fuel/h Loss Corr
 


Warm 3111 kg fuel/h Loss Corr
 


Warm 2037 kg fuel/h Loss Corr

 6.0E+06 Warm 1173 kg fuel/h Loss Corr
 

Warm 668 kg fuel/h Loss Corr
 

Warm 506 kg fuel/h Loss Corr

4.0E+06 

2.0E+06 

0.0E+00
 


1 10 100
 


Particle Diameter (nm)
 


1.4E+07 

Cold 421 kg fuel/h (b) Cold 690 kg fuel/h 

Cold 1221 kg fuel/h 1.2E+07 

Cold 2004 kg fuel/h
 


Cold 3068 kg fuel/h
 


Cold 4479 kg fuel/h

 1.0E+07 Cold 6233 kg fuel/h
 


Cold 6966 kg fuel/h
 


Warm 6307 kg fuel/h

 8.0E+06 Warm 4551 kg fuel/h
 


Warm 3111 kg fuel/h
 


Warm 2037 kg fuel/h

 6.0E+06 Warm 1173 kg fuel/h
 


Warm 668 kg fuel/h
 


Warm 506 kg fuel/h

 4.0E+06 

2.0E+06 

0.0E+00
 


1 10
 
 100 

Particle Diameter (nm) 

dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 

Figure 10-22. Average PSD for a RB211-535E4B engine measured by the Nano-SMPS during 

APEX-3, Test T9, (a) with line loss correction; and (b) without line loss correction. 

150 
8.0E+06 

Cold 179 kg fuel/h Loss Corr (a) Cold 233 kg fuel/h Loss Corr
 

Cold 372 kg fuel/h Loss Corr 7.0E+06 

Cold 524 kg fuel/h Loss Corr
 

Cold 750 kg fuel/h Loss Corr
 

6.0E+06 Cold 971 kg fuel/h Loss Corr

dN/dlogDp (1/cm3) 	 


Cold 1171 kg fuel/h Loss Corr
 


Warm 1180 kg fuel/h Loss Corr
 


Warm 982 kg fuel/h Loss Corr
 


Warm 767 kg fuel/h Loss Corr
 


Warm 529 kg fuel/h Loss Corr
 


4.0E+06	 	 Warm 371 kg fuel/h Loss Corr
 

Warm 231 kg fuel/h Loss Corr
 

Warm 178 kg fuel/h Loss Corr
 

5.0E+06 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00
 

1 10 100
 

Particle Diameter (nm)
 

8.0E+06 

Cold 179 kg fuel/h (b) Cold 233 kg fuel/h 

7.0E+06	 	 Cold 372 kg fuel/h
 

Cold 524 kg fuel/h
 

Cold 750 kg fuel/h
 

6.0E+06	 	 Cold 971 kg fuel/h
 

dN/dlogDp (1/cm3)

Cold 1171 kg fuel/h
 


Warm 1180 kg fuel/h

 5.0E+06 Warm 982 kg fuel/h
 


Warm 767 kg fuel/h
 


Warm 529 kg fuel/h

 4.0E+06 

Warm 371 kg fuel/h
 


Warm 231 kg fuel/h
 


3.0E+06 Warm 178 kg fuel/h



2.0E+06 

1.0E+06 

0.0E+00
 

1 10
 100 

Particle Diameter (nm) 

Figure 10-23. Average PSD for an AE3007-A1/1 engine measured by the Nano-SMPS during 

APEX-3, Test T10, (a) with line loss correction; and (b) without line loss correction. 

151 
152
 


dN/dlogDp (1/cm3) dN/dlogDp (1/cm3) 1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

1 

1.2E+07 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

1 

381 kg fuel/h Loss Corr 

431 kg fuel/h Loss Corr 

622 kg fuel/h Loss Corr 

1090 kg fuel/h Loss Corr 

1530 kg fuel/h Loss Corr 

2179 kg fuel/h Loss Corr 

2815 kg fuel/h Loss Corr 

3564 kg fuel/h Loss Corr 

(a) 

10 100
 

Particle Diameter (nm)
 

381 kg fuel/h 

431 kg fuel/h 

622 kg fuel/h 

1090 kg fuel/h 

1530 kg fuel/h 

2179 kg fuel/h 

2815 kg fuel/h 

3564 kg fuel/h 

(b) 

10 100
 

Particle Diameter (nm)
 

Figure 10-24. Average PSD for a CFM56-3B1 engine measured by the Nano-SMPS during APEX-3, 
 

Test T11, (a) with line loss correction; and (b) without line loss correction.
 
 

 

 

0.0E+00 

2.0E+16 

4.0E+16 

6.0E+16 

8.0E+16 

1.0E+17 

1.2E+17 

dEIn/dlogDp (#/kg fuel) 

Base Fuel (EPA 2) Before Corr 

Base Fuel (EPA 2) After Corr 

Hi-Sulfur (NASA 2&3) Before Corr 

Hi-Sulfur (NASA 2&3) After Corr 

Hi-Aromatics (NASA 4&5) Before Corr 

Hi-Aromatics (NASA 4&5) After Corr 

10.4 Effects of Particle Loss Correction on PSD Results 

To examine the effect of particle loss correction on the PSD results, the PSDs under the idle condition 

(7% power), before and after loss correction, were plotted in Figure 10-25 for APEX-1. Shown in this 

figure are Test EPA-2 for base fuel, NASA-2&3 for high sulfur fuel, and NASA-4&5 for high aromatic fuel. 

The six PSD curves in this figure represent the three different fuels: the blue lines show the base fuel, the 

pink lines the high-sulfur fuel, and the green lines the high-aromatic fuel. The PSD curves before particle 

loss correction are shown as fine lines with open dots, and the results after loss correction are shown as 

solid lines. The particle loss correction in this study did not alter the shape of the PSD over the entire 

particle size range. However, this correction did change the results for number of particles emitted. 

1 10 100 

Particle Diameter (nm) 

Figure 10-25. Effects of line particle loss correction on PSD for a CFM56-2C1 during APEX-1 

(Nano-SMPS results). 

The effects of particle loss correction can also be evaluated by comparing the total particle number data, 

GMDs and GSDs of the PSD, before and after line loss correction as obtained by the Nano-SMPS 

measurements. The results of this comparison for all three APEX campaigns are shown in Figure 10-26. 

In Figure 10-26(a), the total particle number concentrations before and after line loss correction show that 

the concentrations after loss correction increased by about a factor of 1.6 for APEX-1, and about 1.2 for 

APEX-2 and APEX-3. The different increases for the three APEX campaigns are considered to be due to 

differences in the sampling line configurations used for these three APEX campaigns. Figure 10-26(b) 

shows that the GMD data after line loss correction were linearly correlated with the data before loss 

correction with a correlation coefficient of approximately 0.99. The straight line had a slope of 0.95, 

indicating that the average particle size was reduced by about 5 percent after sampling line loss 

correction due to the loss of fine particles by diffusion in the sampling line. Figure 10-26(c) indicates that 

the line loss correction had little effect on the GSD results as the slope of the correlation line is close to 

unity. 

153
 

GSD after Loss Correction (-) GMD after Loss Correction (nm) Total Particles after Loss Correction (#/cm3) 

1.4E+07 

(a) APEX-1 y = 1.5656x 

APEX-2 & -3 R2 = 0.9916 

1.0E+07 

1.2E+07 

8.0E+06 

6.0E+06 

4.0E+06 y = 1.2109x 

R2 = 0.9847 

2.0E+06 

0.0E+00 

0.0E+00 2.0E+06 4.0E+06 6.0E+06 8.0E+06 1.0E+07 

Total Particles before Loss Correction (#/cm3) 

45 

(b) 40
 


35
 


30
 


25
 


20
 
 y = 0.9522x 

15 R2 = 0.9877 

10
 


5
 


0
 


0 10 20 30 40 50 

GMD before Loss Correction (nm) 

3.0 

3.5 (c) 

2.5 

1.5 

2.0 y = 0.9948x 

R2 = 0.9837 

1.0 

1.0 1.5 2.0 2.5 3.0 

GSD before Loss Correction (-) 

3.5 

Figure 10-26.	 Comparison of total particle number, GMD and GSD before and after loss correction 

for all tests conducted based on: (a) total particle concentration and (b) GMD and 

(c) GSD. 

154 
 

Thus, in summary, the sampling line loss correction increased the total particle number (mass) and 

slightly reduced the GMD. No effect on the GSD was observed. 

10.5 Effect of Engine Power and Fuel Flow Rate 

The particle GMD was found to track closely with engine fuel flow rate and, in turn, thrust. Figure 10-27 

shows the typical GMD time-series results of two tests: EPA-2 of APEX-1 and T1 of EPA-3. The GMD 

data were obtained by Nano-SMPS and are presented both with and without line loss correction. The fuel 

flow rate data are represented by the red line (refer to the second y-axis on the right). 

To investigate the effect of engine power thrust or fuel flow rate on PSD, the time series GMD and GSD 

data measured by the Nano-SMPS in each APEX test were averaged at the same power settings and 

then plotted against the fuel flow rate as shown in Figure 10-28 for APEX-1, Figures 10-29 and -30 for 

APEX-2, and Figures 10-31 to -34 for APEX-3. The data for APEX-2 and -3 are broken down by engine 

size and cold or warm operation. Since the sampling line particle loss does not affect the overall trend of 

PSD with engine operation conditions, only the results with particle loss correction are presented here. 

These figures show that, in general, the GMD was larger at idle (lowest fuel flow rate), decreased as fuel 

flow rate increased until the minimum value was reached, and then increased again with fuel flow. 

Notable exceptions to this U-shaped pattern include the AE3007 series engines which exhibited an 

almost consistent GMD of ~10 nm across all fuel flow (thrust) levels as indicated in Figures 10-31(a) and 

10-33(a). Most of the GMD values in the figures were obtained from the measurement probe 30 m 

downstream of the engines, which show variation with fuel flow between 10 to 30 nm. Note that in Figure 

10-31(a), the cold engine data for APEX-3 tests T2, T3, T4 and T5 were measured by the 15-m probe, 

and the cold engine data for T8 in Figure 10-32(a) were measured by the 43-m probe. 

The GSD values in Figures 10-29 to -34 were usually near 1.4 at idle, then gradually increased to greater 

than 2 as the fuel flow increased. As shown in Figure 10-31(b) and 10-33(b) for T2 and T3 of APEX-3, the 

GSDs measured at 15 m varied with fuel flow in a pattern different from the other engines tested. 

Figure 10-35(a) and (b) compare the GMDs and GSDs measured by the Nano-SMPS for the four ICAOspecified engine operation modes of idle, takeoff, climb-out, and approach power for different jet engines 

in the three test campaigns. The data in the figures are particle-loss-corrected, and only data from the 30-

m probe are presented. 

The figure shows that, in general, the PM emissions for the approach power condition (30% power) had 

the smallest GMD for all of the engines tested. The largest GMDs and GSDs were obtained during the 

takeoff (100% power) and climb-out (85% power) conditions. These observations suggest that the PSDs 

of PM emissions from the jet engines under both idle (7% power) and approach (30% power) conditions 

were unimodal and consisted of primary nuclei particles. When the engines were operated under the 

takeoff (100% power) and climb (85% power) conditions, accumulation mode particles were formed (by 

either homogeneous nucleation, condensational growth, and/or coagulation to form larger particles) and 

the PSD curves became broader. 

155
 

0 

500 

1000 

1500 

2000 

2500 

3000 

3500 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

Fuel Flow Rate (kg/h) 

Geometric Mean Diameter (nm) 

(a) with loss corr 

without loss corr 

Fuel Flow Rate 

8:00 8:30 9:00 9:30 10:00 10:30 11:00 

Time of Day 

0 

20 

40 

60 

80 

100 

120 

14 

16 

18 

20 

22 

24 

26 

28 

30 

Fuel Flow Rate (kg/h) 

Geometric Mean Diameter (nm) 

(b) with loss corr 

without loss corr 

Fuel Flow Rate 

17:16 17:45 18:14 18:43 19:12 

Time of Day 

Figure 10-27.	 Two typical results of GMD as a function of fuel flow rate for (a) a CFM56-2C1 

engine during APEX-1, Test EPA-2; and (b) for a CFM56-3B1 engine during APEX-3, 

Test T1. 

156
 

157
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


Figure 10-28. The (a) GMD and (b) GSD of the PM emissions measured during APEX-1 for a 

CFM56-2C1 engine as a function of fuel flow. 

0 

5 

10 

15 

20 

25 

30

Geometric Mean Diameter (nm) 

EPA 2 

EPA 3 

NASA 1a 

NASA 2 

NASA 3 

NASA 4 

NASA 5 

(a) 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

Geometric Standard Deviation 

EPA 2 

EPA 3 

NASA 1a 

NASA 2 

NASA 3 

NASA 4 

NASA 5 

(b) 
 

0 1000 2000 3000 4000 5000
 


Fuel Flow Rate (kg/h)
 


0 1000 2000 3000 4000 5000 

Fuel Flow Rate (kg/h) 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22

Geometric Mean Diameter (nm) 

CFM56-7B24 (T1) Cold 

CFM56-7B24 (T4) Cold 

CFM56-3B1 (T2) Cold 

CFM56-3B2 (T3) Cold 

(a) 

1.0 

1.1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

Geometric Standard Deviation (-) 

CFM56-7B24 (T1) Cold 

CFM56-7B24 (T4) Cold 

CFM56-3B1 (T2) Cold 

CFM56-3B2 (T3) Cold 

(b) 

Figure 10-29.	 The (a) GMD and (b) GSD of the PM emissions measured for three derivatives of the 

CFM56 engine during APEX-2 as a function of fuel flow. Engines operated during 

cold portion of test cycle. 

158
 

22 

21 

20 

19 

18 

17 

16 

15 

14 

13 

12 

(a) CFM56-7B24 (T1) Warm 

CFM56-7B24 (T4) Warm 

CFM56-3B1 (T2) Warm 

CFM56-3B2 (T3) Warm 

0 1000 2000 3000 4000 5000
 


Fuel Flow Rate (kg/h)
 


0 1000 2000 3000 4000 5000 

Fuel Flow Rate (kg/h) 

Geometric Mean Diameter (nm) 

1.0 

1.1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

Geometric Standard Deviation (-) 

CFM56-7B24 (T1) Warm 

CFM56-7B24 (T4) Warm 

CFM56-3B1 (T2) Warm 

CFM56-3B2 (T3) Warm 

(b) 

Figure 10-30.	 The (a) GMD and (b) GSD of the PM emissions measured for three derivatives of the 

CFM56 engine during APEX-2 as a function of fuel flow. Engines operated during 

warm portion of test cycle. 

159
 

 

 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

0 

10 

20 

30 

40 

50 

60 

Geometric Mean Diameter (nm) 

CJ610-8ATJ (T2) 

CJ610-8ATJ (T5) 

AE3007-A1E (T3) 

AE3007-A1E (T4) 

AE3007-A1/1 (T10) 

(a) Cold-Small Engines 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

2.6 

Geometric Standard Deviation (-) 

CJ610-8ATJ (T2) 

CJ610-8ATJ (T5) 

AE3007-A1E (T3) 

AE3007-A1E (T4) 

AE3007-A1/1 (T10) 

(b) Cold-Small Engines 

Figure 10-31.	 The (a) GMD and (b) GSD of the PM emissions measured for the small engines 

during APEX-3 as a function of fuel flow. Engines operated during the cold portion 

of the test cycle. 

160
 

 

0 1000 2000 3000 4000 5000 6000 7000 8000
 


Fuel Flow Rate (kg/h)
 


0 2000 4000 6000 8000 

Fuel Flow Rate (kg/h) 

0 

10 

20 

30 

40 

50 

60

Geometric Mean Diameter (nm) 

CFM56-3B1 (T1) 

CFM56-3B1 (T11) 

PW4158 (T6) 

PW4158 (T7) 

RB211-535E4B (T8) 

RB211-535E4B (T9) 

(a) Cold-Large Engines 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

2.6 

Geometric Standard Deviation (-) 

CFM56-3B1 (T1) 

CFM56-3B1 (T11) 

PW4158 (T6) 

PW4158 (T7) 

RB211-535E4B (T8) 

RB211-535E4B (T9) 

(b) Cold-Large Engines 

Figure 10-32.	 The (a) GMD and (b) GSD of the PM emissions measured for the large engines 

during APEX-3 as a function of fuel flow. Engines operated during the cold portion 

of the test cycle. 

161
 

162
 


Geometric Mean Diameter (nm) 

60 

50
 

40
 

30
 

20
 

10
 

0
 

Warm-Small Engines CJ610-8ATJ (T2) 

(a) CJ610-8ATJ (T5) 

AE3007-A1E (T3) 

AE3007-A1E (T4)
 

AE3007-A1/1 (T10)
 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

Geometric Standard Deviation (-) 

CJ610-8ATJ (T2) 

CJ610-8ATJ (T5) 

AE3007-A1E (T3) 

AE3007-A1E (T4) 

AE3007-A1/1 (T10) 

(b) Warm-Small Engines 

Figure 10-33.	 The (a) GMD and (b) GSD of the PM emissions measured for the small engines 

during APEX-3 as a function of fuel flow. Engines operated during the warm portion 

of the test cycle. 
0 1000 2000 3000 4000 5000 6000 7000 8000
 


Fuel Flow Rate (kg/h)
 


0 2000 4000 6000 8000 

Fuel Flow Rate (kg/h) 

0 

10 

20 

30 

40 

50 

60

Geometric Mean Diameter (nm) 

CFM56-3B1 (T1) 

PW4158 (T6) 

PW4158 (T7) 

RB211-535E4B (T8) 

RB211-535E4B (T9) 

(a) Warm-Large Engines 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

2.6 

Geometric Standard Deviation (-) 

CFM56-3B1 (T1) 

PW4158 (T6) 

PW4158 (T7) 

RB211-535E4B (T8) 

RB211-535E4B (T9) 

(b) Warm-Large Engines 

Figure 10-34.	 The (a) GMD and (b) GSD of the PM emissions measured for the large engines 

during APEX-3 as a function of fuel flow. Engines operated during the warm portion 

of the test cycle. 

163
 

164 

40 

35 

30 

25 

20 

15 

10 

5 

0 

(a) CFM56-2C1 

CFM56-7B24 

CFM56-3B 

CJ610-8ATJ 

AE3007A1/1 

PW 4158 

RB211 

Geometric Mean Diameter (nm) 

Idle Takeoff Climb Approach 

Engine Cycle 

2.8 

Geometric Standard Deviation (-) 

2.6 

2.4 

2.2 

2.0 

1.8 

1.6 

1.4 

1.2 

1.0 

Idle	 Takeoff Climb 

(b) CFM56-2C1 

CFM56-7B24 

CFM56-3B 

CJ610-8ATJ 

AE3007A1/1 

PW 4158 

RB211 

Approach 

Engine Cycle 

Figure 10-35.	 Comparison of: (a) GMD and (b) GSD under four ICAO power conditions for 

different engine types. 
 

10.6 Effects of Fuel Type 

To investigate the effects of fuel type on particle size distribution, the differential number PSDs 

(dN/dlogDp) obtained from APEX-1 for different fuels were compared. Figure 10-36 shows the 

comparisons of the PSDs obtained by the Nano-SMPS for the three different jet fuels (base, high-sulfur 

and high-aromatic) under three engine power levels representative of (a) idle, (b) climb and (c) approach, 

respectively. The three test results used were NASA-1 for base fuel, NASA-3 for high-sulfur fuel, and 

NASA-4 for high-aromatic fuel. Take-off data could not be obtained by the Nano-SMPS due to its slow 

instrument response and relatively short run time under the 100 percent rated thrust condition. Note that 

the test NASA-1 of APEX-1 was run under higher crosswind conditions as discussed previously. This test 

is being used for the discussion here because the NASA-1 test was the only test with all three power 

levels for the base fuel measured by Nano-SMPS. 

Under all three power levels, a unimodal and log-normal PSD was observed regardless of the difference 

in fuel type and power setting. In Figure 10-36, under all three power settings, the base fuel produced the 

smallest number of particles, followed by the high-aromatic fuel and the high-sulfur fuel. This trend is due 

to the conversion of a small fraction of the sulfur in jet fuel to sulfate during combustion. The sulfate then 

becomes part of the PM emissions. The PSD for the high-sulfur fuel peaked at approximately 17 nm 

regardless of the power setting, while the peaks for the PSDs of base and high-aromatic fuels were at 

slightly smaller particle size. Measurement of higher PM emissions from high-aromatic fuel than from 

base fuel is most likely due to unburned hydrocarbons in the high-aromatic fuel being condensed and 

forming additional nuclei particles in the emissions. 

In Figure 10-36(c), the PSD curves under the climb-out power (85%) shows notable “tails” in the larger 

particle size channels (>30 nm) indicative of the formulation of a minor accumulation mode. Under 

approach conditions (30% power), as shown in Figure 10-36(b), the number of particles emitted from all 

three fuels sharply increased, but the particles were still not as numerous as was the case at idle. Again, 

like idle, a higher particle count resulted from the high-sulfur fuel. 

Figure 10-37 also provides a comparison of the average GMDs and GSDs obtained for selected APEX-1 

tests at idle and at 30 and 85 percent rated thrust. The data presented in the figure were particle-losscorrected. As Figure 10-37 shows, the GMDs of the particles produced using high sulfur fuel tend to be 

greater than those for the other two fuel types tested. Also, the GMDs obtained with either high-sulfur or 

high-aromatic fuel showed little effect from changes in engine power. The GMD for high-sulfur fuel was in 

the range of 16-17 nm, the GMD for high-aromatic fuel was between 11-12 nm, and, in contrast, the GMD 

for base fuel varied significantly from ~11 to 17 nm as the engine power changed. Figure 10-37(b) also 

shows that the GSD obtained with base fuel varied by a factor of 1.7 between idle and climb-out power, 

where the GSD exceeded 2.3. 

10.6 Effects of Engine Type 

To investigate the effects of engine type on particle size distribution, Figure 10-38 compares the GMDs 

obtained by the different engines tested during the three APEX campaigns. The results, measured by 

Nano-SMPS at 30 m behind the engines, are presented in the figure. The PSDs for the CJ610-8ATJ (Test 

2 and 5 from APEX-3) and AE3007-A1E (Test 3 and 4 from APEX-3) engines were measured 15 m 

downstream of the engines, and are therefore not presented here. The effect of probe position on the PM 

emission from jet engines is discussed in Section 10.9 below. 

165
 
0.0E+00 

5.0E+06 

1.0E+07 

1.5E+07 

2.0E+07 

2.5E+07 

3.0E+07 

1 10 100 

dEIn/dlogDp (#/kg fuel) 

Particle Diameter (nm) 

(a) Base Fuel (NASA1) 

Hi-Sulfur (NASA3) 

Hi-Aromatic (NASA4) 

0.0E+00 

5.0E+06 

1.0E+07 

1.5E+07 

2.0E+07 

2.5E+07 

3.0E+07 

1 10 100 

dEIn/dlogDp (#/kg fuel) 

Particle Diameter (nm) 

(b) 

0.0E+00 

5.0E+06 

1.0E+07 

1.5E+07 

2.0E+07 

2.5E+07 

3.0E+07 

3.5E+07 

4.0E+07 

1 10 100 

dEIn/dlogDp (#/kg fuel) 

Particle Diameter (nm) 

(c) 

Figure 10-36. Effects of fuel type on PSD for different engine power conditions during APEX-1 for: 

(a) idle (7%), (b) climb-out (85%), and (c) approach (30%). 

166
 
Idle	 Climb Approach 

Idle	 Climb Approach 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20

Geometric Mean Diameter (nm) 

Base (NASA-1) 

Hi-Sulfur (NASA-3) 

Hi-Aromatic (NASA-4) 

(a) 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

Geometric Standard Deviation (-) 

Base (NASA-1) 

Hi-Sulfur (NASA-3) 

Hi-Aromatic (NASA-4) 

(b) 

Figure 10-37.	 Comparison of the loss-corrected: (a) GMDs; and (b) GSDs for different power 

conditions and fuels during APEX-1. 

167
 

 

 

 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

Geometric Mean Diameter (nm) 

CFM56-2C (APEX-1 NASA1a) 

CFM56-7B (APEX-2 T1) 

CFM56-3B (APEX-2 T2) 

AE3007A1/1 (APEX-3 T10) 

P&W 4158 (APEX-3 T6) 

RB211-535E4 (APEX-3 T9) 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Fuel Flow Rate (kg/h) 

Figure 10-38. Comparison of GMDs for different engines. 

Figure 10-38 shows that at low fuel flow rates, all the engines had a GMD of about 10-20 nm, which first 

decreased and then increased as the fuel flow rate increased. For most of these engines, the GMD was 

smallest at the fuel flow rate ranging below ~2,000 kg/h. Also, in comparison to the P&W 4158 engine, the 

GMD of the RB211 engine increased more sharply as the fuel flow rate increased beyond ~3,000 kg/h. 

The GSD data for different engines can be compared as shown in Figure 10-39. The GSD results showed 

a trend similar to the GMD. All of these observed trends suggest that more accumulation mode particles 

were present in the PM emissions when the engines were operated under the higher power settings 

(higher fuel flow rate). Figures 10-38 and 10-39 also show that the P&W 4158 and RB211 engines, which 

were the largest tested in the APEX campaigns, also had larger GMD and GSD at higher fuel flow rates. 

The GMDs of the PM emissions obtained from the six different engines were also compared under the 

four ICAO-specified engine operation modes of takeoff, climb-out, approach and idle, as shown in Figure 

10-40(a) – (d). The data in the figure are particle-loss-corrected, and only 30-m data are presented for 

APEX-3. In Figure 10-40(a), only three engines − CFM56-3B1, AE3007-A1/1 and RB211-535E4-B − have 

Nano-SMPS data at 100 percent power thrust for comparison. At takeoff, the GMD of the PM emissions 

generally increased with engine size. The larger RB211-535E4-B engine had a GMD of about 30 nm, 

followed by 28 nm for the medium-sized CFM56-3B1 engine, with the smaller AE3007-A1/1 engine 

having the smallest GMD (11 nm). When the engines operated at climb mode, Figure 10-40(b) shows that 

the GMD of the RB211-535E4-B engine decreased to ~28 nm and was the largest among all the engines 

tested. The larger P&W 4158 engine ranked second at climb-out with a GMD of 26 nm. 

168
 
 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

Geometric Standard Deviation (-) 

CFM56-2C (APEX-1 NASA1a) 

CFM56-7B (APEX-2 T1) 

CFM56-3B (APEX-2 T2) 

AE3007A1/1 (APEX-3 T10) 

P&W 4158 (APEX-3 T6) 

RB211-535E4 (APEX-3 T9) 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Fuel Flow Rate (kg/h) 

Figure 10-39. Comparison of GSDs for different engines. 

When the engines switched to approach mode, the GMD for all of the engines was significantly reduced 

as shown in Figure 10-40(c). Figure 10-40(d) shows that the engines at idle also had small GMDs, but the 

GMDs measured at idle were slightly larger than those measured at approach mode. 

The GSDs obtained by different engines operated under four modes were compared in Figure 10-41(a) – 

(d). Regardless of engine type, the PM emissions at approach and idle modes generally had lower GSD 

values, in the 1.3 to 1.5 range, except for the RB211-535E4-B engine, which had a GSD of 1.9 at 

approach power. As was the case for GMD, the GSDs increased during takeoff and climb modes. The 

only exception to the GSD increase during takeoff and climb modes was for the small AE3007-A1/1 

engine, which showed little change in GSD value when the engine operated at climb-out power. 

These observations again suggest that the PSDs of PM emissions from the jet engines under both idle 

(7% power) and approach (30% power) conditions were unimodal and consisted of primary nuclei 

particles. When the engines operated under the takeoff (100% power) and climb (85% power) conditions, 

accumulation mode particles were formed and the PSD curves became broader. 

169
 

40
 

(a) Idle 

40 

35
 35
 

0 0 

CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 RB211 CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 

(b) Take-Off 

40
 

(d) Approach 


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Geometric Mean Diameter (nm) Geometric Mean Diameter (nm) 

Geometric Mean Diameter (nm) Geometric Mean Diameter (nm) 30
 30
 25
 25
 20
 20
 15
 15
 10
 10
 5
 5
 40
 (c) Climb 35
 35 30
 30
 25
 25
 20
 20
 15
 15
 10
 10

5
 5
 0 0 

CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 RB211 CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 

Figure 10-40. Comparison of GMD produced by different engines at: (a) idle, (b) takeoff, (c) climb, and (d) approac

170
 

2.6 2.6 

2.4 2.4 

(a) Idle (b) Take-Off 

Geometric Standard Deviation (-) 2.2 2.0 1.8 1.6 1.4 

Geometric Standard Deviation (-) 2.2 2.0 1.8 1.6 1.4 

1.2 1.2 1.0 1.0 

CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 RB211 CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 

Geometric Standard Deviation (-) 

Geometric Standard Deviation (-) 

2.6 2.6 

(c) Climb (d) Approach 

2.4 2.4 2.2 2.0 1.8 1.6 1.4 

2.2 2.0 1.8 1.6 1.4 

1.2 1.2 1.0 1.0 

CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 RB211 CFM56-2C CFM56-7B CFM56-3B AE3007A1/1 PW 4158 

171
 

Figure 10-41. Comparison of GSD produced by different engines at: (a) idle, (b) takeoff, (c) climb, and (d) approac
 

10.7 Effects of Cold and Warm Engine Conditions 

In APEX-2 and APEX-3, the PM emissions were measured under both increasing (cold) and decreasing 

(warm) engine power. Figures 10-10 through 10-13 (for APEX-2) and Figures 10-14 through 10-24 (for 

APEX-3) show that slight differences were observed in the PSD between cold and warm engine 

conditions. To investigate the magnitude of these differences, particle number concentration, GMD and 

GSD obtained at different power settings under cold engine conditions were plotted against the 

corresponding data under warm engine conditions in Figure 10-42(a), (b) and (c), respectively. Figure 10-

42(a) shows that the particle number concentration data obtained from cold engines were linearly 

correlated with the data obtained from warm engines, with a correlation coefficient of 0.91. The straight 

line had a slope of 0.925, indicating that the particle number concentrations were ~7 percent lower with 

warm engines than they were with cold engines. Figures 10-42(b) and (c) show that the correlation lines 

between cold and warm engine conditions have slopes equal to 1 for both GMD and GSD. Engine warmup results in fewer particles being emitted, but does not markedly change the particle size distribution. 

10.8 Effect of Probe Position on PSD 

During the APEX-3 campaign, the effect of sampling probe location on the PM emissions was 

investigated in tests T5 and T8. In test T5, the emissions from the CJ610-8ATJ turbojet engine were 

sampled at two locations. The data were first collected by the 15-m sampling probe as the engine power 

increased step-by-step at the rated thrust levels of 7, 30, 45, 65, 85, and 100 percent. Samples were then 

collected by the 30-m probe while the engine power setting was switched in opposite order from 100 to 7 

percent. The same procedure was used to compare the results between the 30-m and 43-m probes in 

test T8 for the RB211-535E4-B engine. However, the data were comparable only at the power setting 

levels of 4, 7, 15, 30, 45 and 65 percent. The engine was tested at up to 85 percent thrust, but the 

emissions were only measured at 30 m. 

The probe position effects on PM emissions were first investigated by comparing the three characteristic 

parameters of the PSDs measured by Nano-SMPS at different distances from the tested engines. Figure 

10-43(a) – (c) shows the particle number concentration, GMD and GSD, respectively, plotted against the 

engine thrust as measured by the 30-m and 15-m probes during APEX-3 test T5. Figure 10-43(b) shows 

that the GMD measured by the 30-m probe was lower than the GMD measured by the 15-m probe under 

all the engine power settings, with the exception of 7 percent idle. The GSD measured by 30-m probe, on 

the other hand, was greater than the GSD measured by 15-m probe at all power levels. As the plume 

moved from 15-m to 30-m downstream of the engine, more nuclei mode particles were formed in the 

plume, which reduced the average particle size and widened the size distribution. The exception at idle 

seen in Figure 10-43(b) shows that smaller GMDs were obtained from the 15-m probe, indicating 

compositional differences in the particles produced at lower power settings. At higher power settings (i.e., 

fuel flow), the engine seems to produce more volatiles, which formed additional nuclei mode particles 

from the gas phase as the plume traveled farther downstream of the engine. 

172
 

173
 


y = 0.9248x

R2 = 0.9126 

0.0E+00 

1.0E+06 

2.0E+06 

3.0E+06 

4.0E+06 

5.0E+06 

6.0E+06 

C N Measured Under Warm Condition (#/cm3 ) 

(a) 

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06 

CN Measured Under Cold Condition (#/cm3) 

y = 1.0011x

R2 = 0.9258 

0 

5 

10 

15 

20 

25 

30 

35 

40 

GMD Measured Under Warm Condition (nm) 

(b) GMD 

0 5 10 15 20 25 30 35 40
 

GMD Measured Under Cold Condition (nm)
 

y = 1.0011x

R2 = 0.9258 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

2.2 

2.4 

GSD Measured Under Warm Condition (nm) 

(c) GSD 

1.0 	 1.2 1.4 1.8 2.2 1.6 2.0 2.4 

GSD Measured Under Cold Condition (nm) 

Figure 10-42. Effect of engine operating temperature on: (a) PM number concentration; (b) GMD; 

and (c) GSD. 
40 

Particle Number Concentration (particles/cm3 ) 

1.0E+07 

8.0E+06 

6.0E+06 

4.0E+06 

2.0E+06 

0.0E+00 

15-m Probe 

30-m Probe 

(a) 

7 30 45 65 85 100 

Rated Thrust (%) 

15-m Probe 

30-m Probe 

(b) 

7 30 45 65 85 100 

Rated Thrust (%) 

35 

30 

	 25

2.4 

20 

15 

10 

5 

0 

15-m Probe 

30-m Probe 

(c) 

2.2 

2.0 

1.8 

1.6 

1.4 

1.2 

1.0 

GSD (-) 

7 30 45 65 85 100 
 

Rated Thrust (%) 
 

GMD (nm) 

Figure 10-43.	 Comparisons of: (a) particle number concentration; (b) GMD; and (c) GSD measured 

by the 15- and 30-m probes during APEX-3 T5 (Nano-SMPS; line-loss corrected). 

174 
 

Figure 10-44(a) - (c) show the particle concentration, GMD and GSD measured using the 30-m and 43-m 

probes from APEX-3 test T8 for the RB211-535E4-B engine. The comparison shows similar trends to 

those observed in APEX-3 test T5. Figure 10-44(b) shows that the GMDs measured at 43-m were lower 

than the GMDs measured at 30 m at power levels greater than 15 percent, again indicating that, at higher 

power settings, the formation of fine particles by the nucleation and condensation of volatiles continued to 

dominate as the plume moved from the 30- to 43-m probe location. At lower power settings, as was seen 

in test T5 for the 15-m and 30-m comparison, the GMD was larger at 43-m than that at 30-m. The GSD 

measured by the 43-m probe at power settings above 7 percent was greater than the GSD measured by 

the 30-m probe, as shown in Figure 10-44(c), consistent with the observation in APEX-3 test T5. This 

result is considered to be mainly a result of the formation of additional sulfate particles from the gas 

phase as reported by Wey et al. (2006). 

Both Figures 10-43(a) and 10-44(a) show that, at higher power settings, the particle number 

concentration decreased as the plume traveled farther downstream of the engine, possibly because of the 

dilution of the plume by ambient air during transit. 

The effects of probe position on particle number and mass were further investigated using the numberand mass-based EIs derived from the Nano-SMPS measurements in the APEX-3 T5 and T8 tests. Figure 

10-45 shows the comparison between the particle number emission indices (EIN) measured by the 15-m 

and 30-m probes for test T5 with the CJ610-8ATJ engine and T8 of the RB211-535E4-B engine. Although 

the particle number EIs varied differently with power settings for these two engines, at lower power 

settings the EIN decreased as the probe moved farther from the engine and, at higher power settings, the 

EIN increased with distance. The increase in EIN at higher power settings as the plume traveled farther is 

probably attributable to the nucleation of volatiles, while the EIN decrease at engine idle may imply some 

different mechanism for particle transformation under lower power conditions. 

For particle mass emissions, Figure 10-46 compares the mass emission indices (EIM) measured at 

different probe positions for APEX-3 test T5 for the CJ610-8ATJ engine and APEX-3 test T8 for the 

RB211-535E4-B engine. The figure shows that, for both engines, the EIM values decreased with travel 

distance of the plume, and that the trends were consistent for most power setting levels. The only 

exception was for the RB211 engine at 4 and 65 percent thrust, where the EIM was higher at the 43-m 

probe position than that at 30-m. The decrease in EIM observed here is in conflict with the EIN results 

discussed above. This decrease may be partly attributed to the EIM results being converted from the 

Nano-SMPS number measurements, which were affected by the PSDs measured. Note also that in 

APEX-3 test T5 and T8, the first measurements were made at the probe location closer to the engine 

when the engine was operating under the cold condition, resulting in the measurements at the more 

distant probe position always being collected under warm engine conditions. The engine condition may 

have also affected these results. Additional research would be needed to help explain the above 

experimental results. 

175
 

35 

GMD (nm) Particle Number Concentration (particles/cm3) 

6.0E+06 

5.0E+06 

4.0E+06 

3.0E+06 

2.0E+06 

1.0E+06 

0.0E+00 

30-m Probe 

43-m Probe 

(a) 

4 7 15 30 45 65 85 

Rated Thrust (%) 

30-m Probe 

43-m Probe 

(b) 

4 7 15 30 45 65 85 

Rated Thrust (%) 

30 

25 

20 

15 

10 

5 

0 

2.8 30-m Probe 

43-m Probe 

(c) 

2.6 

2.4 

2.2 

	 GSD (-) 2.0 

1.8 

1.6 

1.4 

1.2 

1.0 

4	 7 15 30 45 65 85
 

Rated Thrust (%) 
 

Figure 10-44.	 Comparisons of: (a) particle number concentrations; (b) GMD; and (c) GSD 

measured by the 30- and 43-m probes during APEX-3 T8 (EEPS; line-loss 

corrected). 

176
 
177
 


PM Emission Index (particles/kg fuel) PM Emission Index (particles/kg fuel) 

2.0E+16 

1.5E+16 

1.0E+16 

5.0E+15 

0.0E+00 

3.5E+16 

3.0E+16 

2.5E+16 

2.0E+16 

1.5E+16 

1.0E+16 

5.0E+15 

0.0E+00 

CJ610-8ATJ (APEX-3 T5) 15-m Probe 

30-m Probe 

7 30 45 65 85 100

Rated Thrust (%)
 

RB211-535E4 (APEX-3 T8) 30-m Probe 

43-m Probe 

4 7 15 30 45 65
 

Rated Thrust (%)
 

Figure 10-45.	 Effects of probe position on particle number emission indices for a: CJ610-8ATJ 

turbojet; and RB211-535E4B turbofan engine. 
178
 


7 30 4	 5 65 85 100

Rated Thrust (%)
 


4 7 15 30 45 65
 


Rate Thrust (%)
 


0 

100 

200 

300 

400 

500 

600 

700 

800 

PM Emission Index (mg/kg fuel) 

CJ610-8ATJ (APEX-3 T5) 15-m Probe 

30-m Probe 

0 

50 

100 

150 

200 

250 

300 

350 

PM Emission Index (mg/kg fuel) 

RB211-535E4 (APEX-3 T8) 30-m Probe 

43-m Probe 

Figure 10-46.	 Effects of probe position on particle mass emission indices for a: CJ610-8ATJ 

turbojet; and RB211-535E4B turbofan engine. 
10.9 Comparison of PSDs Measured by Different Instruments 

The GMD and GSD data of the particle size distributions, as measured by Nano-SMPS and EEPS, were 

compared. The comparison of particle number emission indices measured by different instruments was 

discussed previously in Section 9 (PM Number Emissions). Figure 10-47 plots the results from the NanoSMPS against those of the EEPS under the same test conditions for all APEX-2 and APEX-3 tests. 

Therefore, these graphs show the average of tests T1 to T4 from APEX-2 for the CFM56-7B24, -3B1, and 

-3B2 engines; and tests T1 to T11 from APEX-3 for the CFM56-3B1, CJ610-8ATJ, AE3007-A1E and – 

A1/1, P&W 4158 and RB211-535E4-B engines. 

Figure 10-47(a) shows the comparison of GMD results measured by the two instruments. The correlation 

line in the figure shows a slope of 0.84, indicating that the GMDs measured by the EEPS were ~16 

percent smaller than those measured by the Nano-SMPS. For most of the measurement results, a weak 

linear correlation between the two instruments can be observed, with a correlation coefficient of ~0.6. The 

GSD comparison is shown in Figure 10-47(b), where the weak linear correlation between the two 

instrument measurements can again be observed (correlation coefficient is ~0.5). The slope of the 

correlation line is 0.98, indicating that the PSD measurements by the two instruments had nearly the 

same standard deviations. 

179
 

180
 

50 

(a) 

40 

30 

y = 0.8417x

R2 = 0.5833 

20 

10 

0 

GMD by EEPS (nm) 

0 5 10 15 20 25 30 35 40 45 

GMD by nano-SMPS (nm) 

3.0 

(b) 

y = 0.9752x 

R2 = 0.5169 

1.0	 1.5 2.0 2.5 3.0 

2.5 

	 GSD by EEPS (-) 2.0 

1.5 

1.0 

GSD by nano-SMPS (-) 

Figure 10-47.	 Comparison of the GMD and GSD as obtained from Nano-SMPS and EEPS 

measurements during all tests conducted during APEX-2 and -3. 
11. Black Carbon and PAH Emissions 

The PM emissions from aviation gas turbine engines consist of a number of components including black 

carbon (BC) as well as other organic compounds, inorganic acids and salts, etc., which are generated 

during the combustion process. In the APEX test series, black carbon was continuously monitored using 

a Magee Aethalometer and particle surface-bound PAHs were continuously monitored by a PAS 2000 

instrument. The data collected from these two analyzers are summarized in this section with details 

provided in Appendix G. All results provided were background-corrected using data collected before/after 

each test. 

However, the quality of the data collected by the aethalometer and PAH analyzer was generally poor. The 

data were highly variable and often did not respond to changes in engine power. Therefore, only selected 

data are being presented here for the sake of completeness and the analysis of trends. All continuous BC 

and PAH results should be used with extreme caution and certainly should not be used in absolute terms. 

11.1 Black Carbon Emissions 

The black carbon (BC) content in PM emissions was continuously monitored by the Magee Aethalometer 

for all the three APEX campaigns. The data were recorded every second. The time-series BC 

concentration data for individual tests are presented in Figures 11-1 to 11-8. In the figures, the black lines 

represent the recorded black carbon concentration and the rated power thrust was plotted using the 

second y-axis. Also note the very high degree of variability in the data produced by the aethalometer. 

Figure 11-1 consists of the results of four tests: EPA-1, EPA-2, NASA-1, and NASA-1a of APEX-1 

campaign. These tests were conducted with the same CFM56-2C1 engine and base jet fuel. The BC 

concentrations measured for EPA-2 and NASA-1a were well correlated to the variation in engine power 

thrust. The responses for the EPA-1 and NASA-1 tests were poor and may have been caused by the 

crosswind background interference. 

The CFM56-2C1 engine was also tested with high-sulfur fuel during APEX-1 tests EPA-3, NASA-2 and 

NASA-3. The BC concentrations recorded for NASA-2 were found to be unrealistically high during some 

of the test period, and the BC data for EPA-3 and NASA-3 did not correlate well with the power settings. 

Therefore, these tests were not used in the data analysis. 

Figure 11-2 shows the BC concentrations measured for the CFM56-2C1 engine with high-aromatic fuel. 

The two APEX-1 tests, NASA-4 and NASA-5, are presented in the figure. The data show some 

correlation between the BC concentration and the rated power thrust, though there was large fluctuation 

in these tests. 

181
 
The BC concentration results of APEX-2 T1 and T4 tests for the CFM56-7B24 engine are shown in Figure 

11-3, with the results of the T2 and T3 of APEX-2 and the T1 and T11 of APEX-3 presented in Figure 

11-4. As shown, there is some correlation of the BC measurements with power changes. 

Figure 11-5 presents the results of APEX-3 T2 and T5 for the CJ610-8ATJ engine. The discrepancy 

between the BC concentration change with ascending and descending power variation were believed to 

be caused primarily by the probe position change. The probe position was changed during these two 

tests. This change in the probe position will be discussed further in a later subsection. 

Figures 11-6, 11-7, and 11-8 are the results for the AE3007-A series, P&W 4158 and RB211 engines, 

respectively, during APEX-3. The BC concentrations recorded in these tests show good correlation with 

power change. The results of the test T8 of APEX-3 in Figure 11-8 were obtained from the two probe 

positions. The effect of probe position will be discussed later. 

The tests during which the black carbon monitoring results were not correlated to engine power are 

indicated in Table 11-1. Also note that all data presented are uncorrected for losses in the sampling lines 

since this parameter was not measured during the line loss determination. 

0 

20 

40 

60 

80 

100 

0 

1 

2 

3 

4 

5 

6 

7 

8 

12:00 12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 

Rated Thrust (%) 

Black Carbon Concentration (mg/m3) 

Time of Day 

Black Carbon 

Rated Thrust 

APEX-1 EPA-1 

Figure 11-1. Time-series black carbon concentration data for the tests EPA-1, EPA-2, NASA-1, 

and NASA-1a of APEX-1 campaign for the CFM56-2C1 engine with base fuel. 

182
 

Figure 11-2.	 	 Time-series black carbon concentration data for the tests NASA-4 and NASA-5 of 

APEX-1 campaign for the CFM56-2C1 engine with high-aromatic fuel. 

183 
184
 


Figure 11-3. Time-series black carbon concentration data for the tests T1 and T4 of APEX-2 

campaign for the CFM56-7B24 engine. 
185
 


Figure 11-4. Time-series black carbon concentration data for the tests T2 and T3 of APEX-2 and 

T1 and T11 of APEX-3 for the CFM56-3B series engine. 
186 

Figure 11-5.	 	 Time-series black carbon concentration data for the APEX-3 T2 and T5 for the 

CJ610-8ATJ turbojet engine. 
187
 


Figure 11-6. Time-series black carbon concentration data for the APEX-3 T3 and T4 for the 

AE3007A1E engine and T10 for the AE3007A1/1 engine. 
188
 


Figure 11-7. Time-series black carbon concentration data for the APEX-3 T6 and T7 for the P&W 

4158 engine. 
189
 


Figure 11-8. Time-series black carbon concentration data for the APEX-3 T8 and T9 for the 

RB211-535E4-B engine. 
 

Table 11-1. Black Carbon Monitoring in APEX Tests 

Campaign 

Aircraft Engine Fuel 

Type Probe Position 

Concentration 

correlated with 

engine power?b APEX Test No. 

EPA-1a 30-m N 

EPA-2 

Base 

30-m Y 

NASA-1a

 30-m N 

NASA-1a 30-m Y 

1 EPA-3 DC-8 CFM56-2C1 30-m N 

NASA-2 Hi-S 30-m N 

NASA-3 30-m N 

NASA-4 

Hi-A 

30-m Y 

NASA-5 30-m Y 

T1 B737- CFM56-7B24 

30-m Y 

2 

T4 70030-m Y 

T2 B737- CFM56-3B1 30-m Y 

T3 300CFM56-3B2 30-m Y 

T1a 

B737- CFM56-3B1 

30-m N 

T11 300 30-m Y 

T2 NASA 

Lear CJ610-8ATJ 

15-m Y 

T5 Model 

25 

turbojet 30-m/15-m Fleet Y 

3 

T3 

Embraer 

EMB145 

AE3007A1E 

15-m Y 

T4 15-m Y 

T10 AE3007A1/1 30-m Y 

T6 

A300 P&W 4158 

30-m Y 

T7 30-m Y 

T8 

B757 RB211-

535E4-B 

30-m/43-m Y 

T9 30-m Y 

a

 Indicates the tests with high cross wind in background. 

b

 N = no; Y = yes. 

190
 

 

11.1.1 Effect of Fuel Flow Rate and Engine Thrust 

The effect of fuel flow rate on the BC emission index was investigated. By averaging the fuel flow rates 

and BC concentration readings that were recorded under the same rated power within a test, the average 

BC concentrations as well as the corresponding average fuel flow rates at various power levels were 

calculated for each test. The average BC emission indices were then calculated from the average CO2 

concentration and summarized in Table G-1 in Appendix G. Figures 11-9 to 11-15 plot the BC emission 

index as a function of fuel flow rate. Note that only the results obtained from the 30-m probe are 

discussed here. The effect of probe position will be discussed later. 

In these figures, the results of different tests with the same engine and fuels were plotted for comparison. 

Figure 11-9 shows the large uncertainty in the APEX-1 black carbon measurement. In comparison, the 

BC measurements for the APEX-2 and APEX-3 campaigns, shown in Figures 11-10 to 11-15, were much 

better. These figures show that the fuel flow rate had effects on the BC emission index similar to those 

observed for the PM mass emission index. A U-shaped curve of EI vs. fuel flow was determined where 

the emissions are slightly elevated near idle, decreases to a minimum at mid-range power, and then 

increases to the maximum at climb-out or take-off power. 

Five engines in this study had black carbon emission data collected at 30-m for the four ICAO- specified 

engine powers: idle (7%), takeoff (100%), climb (85%), and approach (30%). These five engines are 

CFM56-2C1, CFM56-3B series, CJ610-8ATJ, AE3007A1/1, and RB211-535E4-B. The data for the 

AE3007A1/1 engine collected at 8.4 percent rated thrust were used to represent the results of the idle 

engine condition and were compared with the data of the other engines at seven percent rated thrust. The 

emission indices derived from the black carbon measurements under the same engine thrust were 

averaged and summarized in Table 11-2. 

The effects of the LTO engine cycle on the BC emission index for different engines are illustrated in 

Figure 11-16. This figure shows the same trend of BC EI with the change in engine power, although the 

absolute EI values were different for the different engines at the same engine power. In general the BC 

emission indices were the highest at takeoff and climb and became the lowest when the engine was at 

idle and approach modes. The engines operated under approach mode emitted slightly more or less 

black carbon than under idle. These results are consistent with those reported by Wey et al. (2006) and 

Lobo et al. (2007) for APEX-1 and -2. The reported results indicate that the BC emissions are generally 

greater at higher engine power. 

191
 

192
 


Black Carbon Emission Index (mg/kg fuel) Black Carbon Emission Index (mg/kg fuel) 

600
 

500
 

400
 

300
 

200
 

100
 

0
 

0 

600
 

500
 

400
 

300
 

200
 

100
 

0
 

0 

APEX-1 EPA2 

APEX-1 NASA1a 

CFM56-2C 

Base Fuel 

500 1000 1500 2000 2500 3000 3500
 

Fuel Flow Rate (kg/h) 

CFM56-2C
 

High-Aromatic
 

APEX-1 NASA-4
 

APEX-1 NASA-5
 

500 1000 1500 2000 2500 3000 3500
 

Fuel Flow Rate (kg/h) 

Figure 11-9. Black carbon emission index as a function of fuel flow rate for the CFM56-2C1 

engine during APEX-1. 
 

0 

100 

200 

300 

400 

500 

600 

700

Black Carbon Emission Index (mg/kg fuel) 

APEX-2 T1 

APEX-2 T4 

CFM56-7B 

0 1000 2000 3000 4000 5000 

Fuel Flow Rate (kg/h) 

 

Figure 11-10.	 Black carbon emission index as a function of fuel flow rate for the CFM56-7B24 

engine. 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

Black Carbon Emission Index (mg/kg fuel) 

APEX-2 T2 

APEX-2 T3 

APEX-3 T11 

CFM56-3B 

0 500 1000 1500 2000 2500 3000 3500 4000 

Fuel Flow Rate (kg/h) 

Figure 11-11.	 Black carbon emission index as a function of fuel flow rate for the CFM56-3B series 

engine. 

193 
 

0 

200 

400 

600 

800 

1000 

1200 

1400 

Black Carbon Emission Index (mg/kg fuel) 

APEX-3 T5 

CJ610-8ATJ 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

Figure 11-12.	 Black carbon emission index as a function of fuel flow rate for the CJ610-8ATJ 

turbojet engine. 

0 

50 

100 

150 

200 

250 

300 

350 

Black Carbon Emission Index (mg/kg fuel) 

APEX-3 T10 

AE3007A1/1 

0 200 400 600 800 1000 1200 1400 

Fuel Flow Rate (kg/h) 

Figure 11-13. Black carbon emission index as a function of fuel flow rate for the AE3007A1/1 

engine. 

194 
 

 

195
 


0 

100 

200 

300 

400 

500 

600 

700 

Black Carbon Emission Index (mg/kg fuel) 

APEX-3 T6 

APEX-3 T7 

P&W 4158 

0 1000 2000 3000 4000 5000 6000 7000 8000
 

Fuel Flow Rate (kg/h)
 

Figure 11-14. Black carbon emission index as a function of fuel flow rate for the P&W 4158 
 

engine.
 

1600
 

Black Carbon Emission Index (mg/kg fuel) 1400
 

1200
 

1000
 

800
 

600
 

400
 

200
 

0
 

APEX-3 T8 

APEX-3 T9 

RB211-535E4 

0 1000 2000 3000 4000 5000 6000 7000 8000
 

Fuel Flow Rate (kg/h) 

Figure 11-15. Black carbon emission index as a function of fuel flow rate for the RB211-535E4B 

engine. 
 

Table 11-2. BC Emission Indices at the LTO Power Levels for Different Engines 

Engine Test Average Engine Cycle 

BC 

EI SD 

mg/kg mg/kg 

Idle (7%) 33.6 46.2 

CFM56-2C1 APEX-1 EPA-2 

& NASA-1a 

Takeoff (100%) 71.2 81.6 

Climb (85%) 402 113 

Approach (30%) 99.5 174 

Idle (7%) 260 204 

CFM56- APEX-2 T1&T4 

Takeoff (100%) - -

7B24 Climb (85%) 406 168 

Approach (30%) 111 60.9 

Idle (7%) 333 92.6 

CFM56-3B APEX-2 T2&T3 Takeoff (100%) 734 58.5 

series APEX-3 T11 Climb (85%) 718 236 

Approach (30%) 205 27.1 

Idle (7%) 137 651 

CJ610-8ATJ APEX-3 T5 

Takeoff (100%) 808 378 

Climb (85%) 853 106 

Approach (30%) 289 72.3 

Idle (8.4%) 108 192 

AE3007A1/1 APEX-3 T10 

Takeoff (100%) 190 97.3 

Climb (85%) 154 77.4 

Approach (30%) 53.6 85.1 

Idle (7%) 209 229 

P&W 4158 APEX-3 T6&T7 

Takeoff (100%) - -

Climb (80%) 386 135 

Approach (30%) 35.4 60.5 

Idle (7%) 142 172 

RB211- APEX-3 T8&T9 

Takeoff (100%) 665 140 

535E4-B Climb (85%) 873 65.9 

Approach (30%) 191 72.6 

196
 

0 

100 

200 

300 

400 

500 

600 

700 

800 

900 

1000

Black Carbon Emission Index (mg/kg fuel) 

CFM56-2C 

CFM56-7B 

CFM56-3B 

CJ610-8ATJ 

AE3007A1/1 

P&W 4158 

RB211 

Idle (7%) Takeoff (100%) Climb (85%) Approach (30%) 

Figure 11-16. Effect of engine cycle on BC emission index for multiple engine types. 

11.1.2 Effect of Fuel Composition 

To investigate the effects of fuel type on the BC emissions, the APEX-1 test results with different types of 

fuels were evaluated. Figure 11-17 compares the BC emission indices for the base and high-aromatic 

fuels. The BC emission indices in the figure are the average values obtained from the data at the same 

rated thrust levels for the same fuel. For the base fuel, the data from the APEX-1 test NASA-1a were 

averaged, and the data for the high-aromatic fuel were from the test NASA-5. There were no BC data for 

the high-sulfur fuel tests in the comparison because, as discussed previously, the BC measurements for 

tests EPA-3, NASA-2 and NASA-3 were not reliable. The BC emission index data for each fuel type were 

plotted against fuel flow rate. The fuel type appeared to have little effect on the BC emission index. The 

difference in BC emission indices between the base fuel and the high-aromatic fuel was insignificant in 

comparison to the experimental errors. 

To assess the effect of sulfur content, the black carbon emission indices obtained from all the tests with 

the CFM56 engine were plotted in Figure 11-18 against the sulfur content in the fuel, including the data 

obtained from the -2C1, -3B, and -7B24 models in all the three APEX campaigns. The BC emission 

indices are the averages at the same engine rated thrust level and fuel sulfur content. The figure shows 

that, unlike the PM mass emission index, the BC emission index was not directly correlated to the sulfur 

content of the jet fuel. Our finding that BC EI is independent of fuel type is consistent with the 

observations of other APEX investigators (Lobo et. al., 2007). 

197
 

198
 

 

0 

100 

200 

300 

400 

500 

600 

700 

800 

Black Carbon Emission Index (mg/kg fuel) 

Base Fuel 

Hi-Aromatic 

CFM56-2C 

0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


Figure 11-17.	 Comparison of black carbon emission indices obtained from different types of fuel 

for the CFM56-2C1 engine during APEX-1. 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

Black Carbon Emission Index (mg/kg fuel) 

7% Rated Thrust 

30% Rated Thrust 

85% Rated Thrust 

100% Rated Thrust 

0 500 1000 1500 2000
 


Sulfur Content in Fuel (ppm)
 


Figure 11-18.	 Effect of sulfur content in fuel on BC emission index for all CFM56 engines tested. 
 

 

11.1.3 Effect of Engine Type 

The average BC emission indices obtained from the different engine types tested were compared in 

Figures 11-19 for the four ICAO engine power levels: idle, take-off, climb, and approach. Only the data 

with the base fuel or fleet fuel and measured at the 30-m sampling location were presented here. The 

data for the tests EPA-1 and NASA-1 of APEX-1 and the test T1 of APEX-3 were not used as discussed 

previously. The data are averages from the different tests with the same engines. The lowest rated thrust, 

8.4 percent, for the AE3007-A1/1 engine, was used as the idle condition and compared with the other 

engines at 7 percent rated thrust. For the P&W 4158 engine, the data available at 80 percent rated thrust 

were averaged and compared with the other engines at 85 percent rated thrust. There were no data 

available at engine take-off (100%) thrust for the CFM56-7B24 and P&W 4158 engines. The fuel flow rate 

is also presented in the figure using the second y-axis. Again note that the fuel flows provided are 

averages for only those test periods where valid BC data were available and may not match those shown 

earlier in Table 7-2. 

The figure shows that the larger engines did not always produce the most BC. In fact, the CJ610-8ATJ 

turbojet, which is the smallest engine with older combustor technology, had highest BC emission indices 

except for idle. The large error bars in the figure indicate that the BC emission data measured in this 

study were highly variable. It is therefore difficult to make any clear conclusion from the above 

observations. More accurate data than can be provided by the aethalometer are needed to reach clear 

conclusions. 

11.1.4 Effect of Cold and Warm Engine Conditions 

In Figure 11-20, all of the BC emission index data under the cold engine condition were plotted against 

the equivalent indices obtained for the same engine type and the same engine power but under the warm 

condition. The black diagonal line in the figure represents the 1:1 relationship where the emission indices 

under cold and warm conditions are identical. The figure also shows the linear regression results (see the 

pink line). The correlation line has a slope of 0.947, indicating that the BC emission indices were 

approximately 5 percent lower after engine warm-up. Therefore, the warm-up of engines can improve 

carbon burn-off. 

11.1.5 Effect of Probe Position 

In the APEX-3 campaign, the effect of the sampling probe distance from the test engine was investigated. 

The emissions were collected at both 15 m and 30 m in test T5 for the CJ610-8ATJ engine and at 30 m 

and 43 m in test T8 for the RB211-535E4-B engine. In the test T5, the data were first collected at 15 m 

while the engine power increased in five steps from 7, 30, 45, 65, 85 to 100 percent rated thrust, and then 

collected at 30 m with the engine power setting varied stepwise downward from 100 to 7 percent. The 

same experimental procedure was used in Test T8, but the rated thrust settings were between 4 and 85 

percent in six steps. 

199
 

200
 


 

900 

800 1400
 

800
 

33.61 260.39 332.90 136.86 107.90 209.28 142.37 

425 

401 

422 

227 

178 

532 

709 

Emission Index Fuel Flow Rate 

Idle (7%) 


 

71.17 733.66 808.40 189.73 665.27 

3148 

3564 

1226 1175 

6976 

Emission Index Fuel Flow Rate 

Take-Off (100%) 


 
 
 
 
 
 

700

Black Carbon Emission Index (mg/kg fuel) 

Fuel Flow Rate (kg/h) 

Black Carbon Emission Index (mg/kg fuel) Black Carbon Emission Index (mg/kg fuel) 


 
 
 


 
 
 
 
 
 
 
 
 
 
 
 
 
 1200
 


 
 700
 

600
 500
 400
 300
 200
 

600
 

1000
 

800
 

500
 400
 300
 200
 

600
 400
 200
 


 
 100
 100
 

0 0 0 

CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 RB211 CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 RB211 

1200
 8000
 

401.56 406.11 718.15 853.30 154.07 385.53 873.44 

2881 

4109 

3446 

1009 976 

7088 

6271 

Emission Index Fuel Flow Rate 

Climb (85%) 500 
 
 
 
 
 
 
 
 


 

99.53 110.94 205.41 289.30 53.59 35.38 191.26 

1023 

1158 

1099 

452 

371 

2298 

2050 

Emission Index Fuel Flow Rate 

Approach (30%) 


 
 
 
 
 
 
 
 
 7000
 450 6000
 5000
 

Black Carbon Emission Index (mg/kg fuel) 1000
 800
 400
 350

Fuel Flow Rate (kg/h) 300
 

600
 4000
 250
 200
 

3000
 2000
 1000
 

400
 200
 

150
 100
 

50
 

0 0 0 

CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 RB211 CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007A1/1 P&W 4158 RB211 

Figure 11-19. Effect of engine type on BC emission index for multiple engine types. 
 

y = 0.947x

R2 = 0.8006 

0 

200 

400 

600 

800 

1000 

1200 

1400 

Black Carbon EI at Warm Condition (mg/kg) 

0 200 400 600 800 1000 1200 1400
 


Black Carbon EI at Cold Condition (mg/kg)
 


Figure 11-20. Effect of engine cold and warm condition on BC emission index. 

The BC emission indices obtained from the different sampling positions for these two engines are 

compared in Figure 11-21. The results show that the BC emission indices of the CJ610-8ATJ engine 

obtained at 15 m were always higher than the indices obtained at 30 m except for idle. For the RB211-

535E4-B engine, the BC emission index was lower at idle and at a rated thrust >65 percent but was 

higher at 30 or 45 percent rated thrust when the sampling probe changed from 30 m to 43 m. The reason 

for higher BC emissions when the probe was closer to the engine is currently unknown. However, this 

result is consistent with the results of measurements of particulate mass based emission indices 

discussed in Section 10, where EIM decreased as the probe distance increased. Since the BC EI should 

not be affected by probe distance, further study without complication by engine cold and warm operating 

condition is required. 

11.1.6 Test-Average Black Carbon Emission Index 

The test-average black carbon emission indices are summarized in Table 11-3. The available testaverage PM mass emission indices and the percentage non-volatile PM obtained from the Teflon filter 

sampling are also presented in the table. The percentage black carbon in PM as shown in the table for 

each test was obtained by dividing the BC EI by the PM EI. The comparison shows that the percentage 

black carbon in PM for most of the APEX tests was higher than the percentage non-volatile PM measured 

from the Teflon filter/thermal denuder sampling. This result implies that there were significant non-volatile 

PM losses in the thermal denuder. The test-average rated power and fuel flow rate for each test shown in 

Table 11-3 were evaluated by taking account of both the time at each power setting and the time for 

transition from one power setting to another. 

201
 

202
 


0 

200 

400 

600 

800 

1000 

1200 

1400 

Black Carbon Emission Index (mg/kg fuel) 

30-m 15-m 

CJ610-8ATJ 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

Black Carbon Emission Index (mg/kg fuel) 

30-m 43-m 

RB211-535E4 

0 1000 2000 3000 4000 5000 6000 7000
 


Fuel Flow Rate (kg/h)
 


Figure 11-21.	 Effect of probe position on BC emission index for the CJ610-8ATJ and 

RB211-535E4B engines. 
 

 

Table 11-3. Test-average PM and BC EIs and BC Fraction in PM 

APEX Test Engine Fuel 

Rated 

Thrust 

Fuel 

Flow 

Teflon Filter Black Carbon 

PM EI NonVolatile EI BC/PM 

% kg/h mg/kg % mg/kg % 

1 EPA-1 19.5 785 107 32.0 Fail 

1 EPA-2 Base 18.8 770 305 38.0 71.3 23.4 

1 NASA-1 Fuel 22.6 635 N/A Fail 

1 NASA-1a 45.1 1559 N/A 166 

1 EPA-3 CFM56-2C1 20.4 797 447 30.7 301 67.4 

1 NASA-2 Hi-Sulfur 38.4 1279 

443 20.7 

Fail 

1 NASA-3 38.6 1277 Fail 

1 NASA-4 Hi- 36.2 1197 

219 34.5 

153 70.0 

1 NASA-5 Aromatic 35.3 1244 168 77.0 

2 T1 CFM56- 30.1 1264 Fail 237 

2 T4 7B24 30.1 1264 Fail 282 

2 T2 31.5 1201 Fail 464 

2 T3 CFM56-3B 30.4 1199 Fail 288 

3 T1 series 36.7 1352 N/A Fail 

3 T11 31.1 1161 267 20.6 275 § 

3 T2 

CJ610-8ATJ 

47.4 618 N/A 592 

3 T5 Fleet 

Fuel 41.0 566 N/A 584 

3 T3 39.3 523 62.5 53.9 

AE3007A1E 116 38.2 

3 T4 43.1 554 137 § 

3 T10 AE3007A1/1 45.0 550 N/A 101 

3 T6 

P&W 4158 

28.5 2344 

268 46.4 

198 73.7 

3 T7 35.0 2968 198 73.7 

3 T8 RB211- 27.5 2087 N/A 667 

3 T9 535E4-B 34.2 2473 384 59.1 559 § 

§ BC/PM percentage exceeds 100%. 

203
 

 

11.2 PAH Emissions 

The particle surface-bound PAH was monitored by the PAS 2000 during all the APEX tests. The data 

were recorded every second. The time-series PAH concentration data for each test are presented in 

Figures 11-22 to 11-29. In these figures, the PAH concentrations were plotted as black lines. The rated 

thrust for each test was plotted as a pink color line using the second y-axis. Again note the variable, and 

sometimes erratic, data produced by the PAH analyzer which were difficult to analyze and significantly 

impacted the resulting EIs. 

Figure 11-22 shows the results of four tests: EPA-1, EPA-2, NASA-1, and NASA-1a of APEX-1 campaign. 

These tests were conducted with the same CFM56-2C1 engine and the same base jet fuel. The PAH 

concentrations measured for the tests EPA-2 and NASA-1a generally tracked with changes in engine 

power. The EPA-1 and NASA-1 tests may have been influenced by the strong crosswind. 

PAH concentration data for the CFM56-2C1 engine with high-sulfur fuel were collected during APEX-1 

Tests EPA-3, NASA-2, and NASA-3. However, as was the case for BC with these tests, the data were 

found to be unreliable and were not used in the data analysis. 

Figure 11-23 shows the PAH concentrations measured for the CFM56-2C1 engine with high-aromatic 

fuel. The NASA-4 and NASA-5 tests of APEX-1 are presented here. The data show some correlation 

between the PAH concentration and the percentage thrust, though large fluctuations were observed. 

The PAH concentration results for APEX-2 T1 and T4 tests for the CFM56-7B24 engine are shown in 

Figure 11-24 and the results of the T2 and T3 of APEX-2 and the T1 and T11 of APEX-3 are presented in 

Figure 11-25. Figure 11-26 presents the results of APEX-3 T2 and T5 for the CJ610-8ATJ engine and 

Figures 11-27, 11-28, and 11-29 are the results for the AE3007A, P&W 4158 and RB211 engines, 

respectively. The tests during which the PAH monitoring results were not correlated to engine power for 

all the APEX tests are summarized in Table 11-4. Also note that all data presented are uncorrected for 

sampling line losses. 

204
 

205
 


Figure 11-22. Time-series PAH concentration data for tests EPA-1, EPA-2, NASA-1, and NASA-1a 
 

of APEX-1 campaign for the CFM56-2C1 engine with base fuel.
 

206
 


Figure 11-23. Time-series PAH concentration data for tests NASA-4 and NASA-5 of APEX-1 

campaign for the CFM56-2C1 engine with high-aromatic fuel. 
207
 


Figure 11-24. Time-series PAH concentration data for tests T1 and T4 of APEX-2 campaign for the 

CFM56-7B24 engine. 
208
 


Figure 11-25. Time-series PAH concentration data for tests T2 and T3 of APEX-2 and T1 and T11 

of APEX-3 for the CFM56-3B series engines. 
209
 


Figure 11-26. Time-series PAH concentration data for the APEX-3 T2 and T5 for the CJ610-8ATJ 

turbojet engine. 
210
 


Figure 11-27. Time-series PAH concentration data for the APEX-3 T3 and T4 for the AE3007A1E 

engine and T10 for the AE3007A1/1 engine. 
211
 


Figure 11-28. Time-series PAH concentration data for the APEX-3 T6 and T7 for the P&W 4158 

engine. 
212
 


Figure 11-29. Time-series PAH concentration data for the APEX-3 T8 and T9 for the RB211­

535E4-B engine. 
Table 11-4. PAH Monitoring in APEX Tests 

Campaign 

Aircraft Engine Fuel 

Type 

Probe 

Position 

Concentration 

Correlated with 

Engine Power?b APEX Test No. 

EPA-1 30-m Na 

EPA-2 

Base 

30-m Y 

NASA-1a 30-m N 

NASA-1 30-m Ya 

1 EPA-3 DC-8 CFM56-2C1 30-m N 

NASA-2 Hi-S 30-m N 

NASA-3 30-m N 

NASA-4 

Hi-A 

30-m Y 

NASA-5 30-m Y 

T1 B737- CFM56-7B24 30-m Y 

2 

T4 70030-m Y 

T2 B737- CFM56-3B1 30-m Y 

T3 300CFM56-3B2 30-m Y 

T1 B737- CFM56-3B1 30-m Ya 

T11 300 30-m Y 

T2 NASA 

Lear CJ610-8ATJ 

15-m Y 

T5 Model 

25 

turbojet 

Fleet 

30-m/15-

m 

Y 

T3 

AE3007A1E 

15-m Y 

3 T4 Embraer 

EMB145 15-m Y 

T10 AE3007A1/1 30-m Y 

T6 

A300 P&W 4158 

30-m Y 

T7 30-m Y 

T8 

B757 RB211-

535E4-B 

30-m/43-

m 

N 

T9 30-m N 

a. indicates tests not used due to high cross wind in background. 

b. N = no; Y = yes. 

213
 

 

11.2.1 Effect of Fuel Flow Rate 

The relationship between the PAH concentration and fuel flow rate was investigated. The PAH 

concentration readings and corresponding fuel flow rate data under the same rated thrust were averaged 

within the test and the results summarized in Table G-2 in Appendix G. The PAH emission indices for 

various tests were then calculated from average CO2 and plotted as a function of fuel flow rate as shown 

in Figures 11-30 to 11-35. Only the results obtained from the 30-m probe are presented in the figures. 

The results of different tests for the same engine and same fuel were plotted together for comparison. 

These figures show that the PAH emission index varied with the fuel flow rate in a pattern similar to that 

observed for black carbon. The PAH EI was slightly elevated at low fuel flow (engine power), reached a 

minimum at mid-range fuel flow (500-2000 kg/h, depending on the type of engine), and increased with 

fuel flow at high engine power. 

11.2.2 Effect of Fuel Composition 

The effects of fuel composition on the PAH emissions were investigated using the data available from the 

APEX-1 campaign. The base fuel data were from the Tests EPA-2 and NASA-1a and the high aromatic 

fuel were from the NASA-4 and NASA-5 tests. The high sulfur fuel results for Test EPA-3 were not used 

for the reasons discussed above. For each type of fuel, the PAH EI values and corresponding fuel flow 

rate at the same rated thrust levels were averaged and compared in Figure 11-36. The figure shows that 

the base fuel had highest PAH emission index. This observation seems to suggest that the PAH 

emissions are primarily determined by factors other than just the aromatic content of the fuel. However, 

this preliminary finding needs further investigation. 

214
 

215
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0 500 1000 1500 2000 2500 3000 3500
 


Fuel Flow Rate (kg/h)
 


0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

0.35 

0.40 

0.45 

0.50 

PAH Emission Index (mg/kg fuel) 

APEX-1 EPA-2 

APEX-1 NASA-1a 

0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

0.35 

0.40 

0.45 

0.50 

0.55 

0.60 

PAH Emission Index (mg/kg fuel) 

APEX-1 NASA-4 

APEX-1 NASA-5 

Figure 11-30.	 PAH emission index as a function of fuel flow for the CFM56-2C1 engine while 

burning: (a) base fuel; and (b) high-aromatic fuel. 
216
 

 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

PAH Emission Index (mg/kg fuel) 

APEX-2 T1 

APEX-2 T4 

0 1000 2000 3000 4000 5000
 

Fuel Flow Rate (kg/h)
 

Figure 11-31. PAH emission index as a function of fuel flow for CFM56-7B24 engines. 

1.8 

PAH Emission Index (mg/kg fuel) 

1.6 

1.4 

1.2 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

APEX-2 T2 

APEX-2 T3 

APEX-3 T11 

0 500 1000 1500 2000 2500 3000 3500 4000
 

Fuel Flow Rate (kg/h)
 

Figure 11-32. PAH emission index as a function of fuel flow for CFM56-3B series engines. 
 
217
 

 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

PAH Emission Index (mg/kg fuel) 

APEX-3 T5 (30-m only) 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


Figure 11-33. PAH emission index as a function of fuel flow for the CJ610-8ATJ turbojet engine. 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

1.6 

1.8 

PAH Emission Index (mg/kg fuel) 

APEX-3 T10 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


Figure 11-34. PAH emission index as a function of fuel flow for the AE3007-A1/1 engine. 
 

218
 


0.5 

PAH Emission Index (mg/kg fuel) 0.4 

0.3 

0.2 

0.1 

0.0 

Fuel Flow Rate (kg/h) 

Base Fuel 

Hi-Aromatic Fuel 

0 500 1000 1500 2000 2500 3000 3500
 


0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

1.6 

PAH Emission Index (mg/kg fuel) 

APEX-3 T6 

APEX-3 T7 

0 1000 2000 3000 4000 5000 6000 7000 8000
 


Fuel Flow Rate (kg/h)
 


Figure 11-35. PAH emission index as a function of fuel flow for the PW4158 engine. 

Figure 11-36. Comparison of PAH emission indices for different fuel types during APEX-1. 
 

11.2.3 Effect of Engine Cycle 

Like black carbon discussed previously, the PAH emission data collected at 30 m from the CFM56-2C1, 

CFM56-3B series, CJ610-8ATJ, AE3007A1/1 and RB211-535E4-B engines under the four ICAOspecified engine thrusts representing idle (7%), takeoff (100%), climb (85%) and approach (30%) were 

used to investigate the effects of the LTO engine cycle. The data for the AE3007A1/1 engine collected at 

a rated thrust of 8.4 percent were used to represent the results of idle engine condition and compare with 

the data of the other engines at 7 percent rated thrust. The average emission index results derived from 

the PAH measurements were averaged for each of the four power levels and summarized in Table 11-5 

for the individual engine types. 

The PAH emission indices derived from the measurement data for the CFM56-2C, CFM56-3B, CFM56-

7B24 and CJ610-8ATJ engines had a trend similar to the trend shown in Figure 11-37(a)-(c). The engines 

all showed lower PAH EI values when engine was at idle and approach and higher PAH EI values when 

the engines were at take-off and climb-out. Also, the CJ610-8ATJ had the highest PAH EI except at idle. 

Figure 11-37 also shows the PAH emissions from the AE3007A1/1 and PW4158 were affected differently 

by engine power. The AE3007A1/1 and PW4158 engines had the highest PAH emission index at idle, 

comparable to the PAH emission index observed at climb-out and take-off. The differences observed 

could have been caused by differences in engine technology or may simply be experimental errors as the 

large error bars in the figure suggest. 

11.2.4 Effect of Engine Type 

The average PAH emission indices obtained from the different engine types tested were compared in 

Figure 11-38. Only the data with the base fuel or fleet fuel and measured at the 30-m sampling location 

were presented here. The data for the Tests EPA-1 and NASA-1 of APEX-1 and Tests T1, T8 and T9 of 

APEX-3 were not used due to lack of response to changes in engine power as mentioned previously in 

Table 11-4. The data were the averages from the different tests of the same engines under each of the 

four ICAO engine power levels. The lowest rated thrust, 8.4 percent, for the engine AE3007A1E was used 

as idle condition and compared with the other engines at 7 percent rated thrust. For the P&W 4158 

engine, the data available at 80 percent rated thrust were averaged and compared with the other engines 

at 85 percent rated thrust. No data were available at engine take-off (100% thrust) for the CFM56-7B24 

and P&W 4158 engines. The PAH EI value for each engine was presented at the bottom of the bars. The 

fuel flow rate is also presented in the figure using the second y-axis. As before, the fuel flows shown only 

represent those periods with valid PAH data. 

As was the case for BC, the figure shows that the CJ610-8ATJ turbojet which is the smallest engine had 

the highest PAH emission indices when this engine was run at approach, climb-out and take-off power. 

The CFM56-2C engine, on the other hand, had the lowest PAH emission indices at all thrust levels. 

11.2.5 Effect of Cold and Warm Engine Conditions 

The PAH emission index data under the cold engine condition were plotted against the indices obtained 

for the same engine type and the same engine power but under warm condition in Figure 11-39. The 

black dashed line in the figure represents where the emission indices under cold and warm conditions are 

identical. The figure also shows the linear regression results (see the pink line), indicating a slight 

reduction in the PAH emission indices after the engine was warmed up. These results are consistent with 

most of the other emission parameters measured during the APEX campaigns, such as the mass and BC 

EIs, which tended to be lower after engine warm up. 

219
 
 

 

 

 

 

Table 11-5. PAH Emission Indices at the Four ICAO Engine Power Levels for Different Engines 

Engine Campaign and Tests Engine Power 

Average 

Fuel Flow 

PAH 

EI SD 

(kg/h) (mg/kg) (mg/kg) 

Idle (7%) 419 0.0127 0.0325 

CFM56-2C1 APEX-1 EPA-2 & NASA-1a Takeoff (100%) 3151 0.319 0.0858 

Climb (85%) 2881 0.319 0.0366 

Approach (30%) 1023 0.00 0.000736 

Idle (7%) 401 0.0814 0.0389 

CFM56- APEX-2 T1 & T4 

Takeoff (100%) 

7B24 Climb (85%) 4109 0.663 0.0514 

Approach (30%) 1158 0.0208 0.0502 

Idle (7%) 419 0.226 0.0361 

CFM56-3B APEX-2 T2 &T3 Takeoff (100%) 3564 0.617 0.184 

series APEX-3 T11 Climb (85%) 3465 1.05 0.0649 

Approach (30%) 1099 0.141 0.0228 

Idle (7%) 227 0.0944 0.352 

CJ610-8ATJ APEX-3 T5 

Takeoff (100%) 1226 3.05 0.267 

Climb (85%) 1009 3.25 0.256 

Approach (30%) 452 1.43 0.137 

Idle (8.4%) 178 1.03 0.601 

AE3007A1/1 APEX-3 T10 

Takeoff (100%) 1175 0.954 0.0749 

Climb (85%) 976 0.847 0.0689 

Approach (30%) 371 0.591 0.0830 

Idle (7%) 532 0.946 0.492 

PW 4158 APEX-3 T9 

Takeoff (100%) 

Climb (80%) 7088 0.985 0.0241 

Approach (30%) 2298 0.00853 0.0144 

220
 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

CFM56-2C1 

CFM56-7B24 

CFM56-3B 

CJ610-8ATJ 

AE3007-A1/1 

PW4158 

Idle (7%) Take-off (100%) Climb-out (85%) Approach (30%) 

PAH Emission Index (mg/kg fuel) 

Figure 11-37. Effect of engine power on the PAH emission index for different engine types. 

221
 

2.0 600 3.5 

0.319132428 0.616941144 3.047126988 0.9541154

3151.264444 

3563.9 

1225.8 1175

Take-off (100%) Fuel Flow 

3.0 500 

0.0127 

0.0814 0.226 0.0944 1.03 0.946 

419 

401 

419 

227 

178 

532 

Idle (7%) Fuel Flow 

(a)

PAH Emission Index (mg/kg fuel) 

Fuel Flow (kg/h) Fuel Flow (kg/h) 

PAH Emission Index (mg/kg fuel) 1.5 2.5 2.0 

1.5 1.0 400 1.0 300 200 0.5 

100 

0.5 

0.0 0 0.0 

CFM56-2C1 CFM56-7B24 CFM56-3B CJ610-8ATJ AE3007-A1/1 PW4158 CFM56-2C1 CFM56-7B24 CFM56-3B CJ610-8ATJ AE3007-A

4.0 8000 1.8 

0.318850069 0.663016958 

1.048438072 

3.250216692 0.847496003 0.985270588 

2881.235333 

4108.7 

3464.776667 

1008.788 976.1217877 

7087.905488 

Climb-out (85%) Fuel Flow 

(c)

0.0208 0.141 1.43 0.591 

1023 

1158 

1099 

452 

371 

Approach (30%) Fuel Flow 

1.6 3.5 7000 

1.4 

PAH Emission Index (mg/kg fuel) 

PAH Emission Index (mg/kg fuel) 3.0 6000 1.2 2.5 5000 1.0 2.0 1.5 4000 3000 0.8 0.6 1.0 2000 

0.4 

0.5 1000 0.0 

0.2 

0 0.0 

CFM56-2C1 CFM56-7B24 CFM56-3B CJ610-8ATJ AE3007-A1/1 PW4158 CFM56-2C1 CFM56-7B24 CFM56-3B CJ610-8ATJ AE3007-A

222
 


Figure 11-38. Effect of engine type on (a) idle, (b) take-off, (c) climb-out and (d) approach PAH emissions. 
 

y = 0.9344x

R2 = 0.9011 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

PAH EI at Warm Condition (mg/kg fuel) 

0.0 0.5 	 1.0 2.0 3.0 4.0 1.5 2.5 3.5 

PAH EI at Cold Condition (mg/kg fuel)
 


Figure 11-39. Effect of engine operating temperature on PAH emissions. 

11.2.6 Effect of Probe Position 

Emissions data were collected at both 15 m and 30 m locations in Test T5 of APEX-3 for the CJ610-8ATJ 

engine and at 30 m and 43 m in Test T8 of APEX-3 for the RB211-535E4-B engine. In the Test T5, the 

data were first collected at 15 m while the engine power increased step by step from 7, 30, 45, 65, 85 to 

100 percent rated thrust, and then collected at 30 m with the engine power setting varied stepwise 

downward from 100 to 7 percent. The same experimental procedure was used in Test T8, but the rated 

thrust settings were 4, 7, 15, 30, 45, 65 and 85 percent. Again, the data for RB211 were deemed 

unreliable and are not presented here. 

The PAH emission indices obtained from the different sampling positions for the CJ610-8ATJ engine 

were compared as shown in Figure 11-40. The results show that the PAH emission index obtained from 

the probe position farther from the engine was generally higher at higher fuel flows (thrust), suggesting 

that more particles with surface-bound PAHs were formed during plume transport from the gas phase. 

This observation is consistent with the previous discussion about more nuclei size particles being formed 

as the plume moves away from the engines. As discussed in Section 10, the GMD decreased and the 

GSD increased with probe distance due to the formation of more nuclei particles during plume processing 

in the near-field atmosphere. 

223
 

 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

PAH Emission Index (mg/kg fuel) 

15-m Probe 

30-m Probe 

0 200 400 600 800 1000 1200 1400
 


Fuel Flow Rate (kg/h)
 


Figure 11-40.	 Effect of probe position on PAH emission index for the CJ610-8ATJ engine during 

APEX-3. 

11.2.7 Test-Average PAH Emission Index 

The test-average PAH emission indices for all the APEX tests are summarized in Table 11-6. By 

averaging the results of the same engines from different tests, Figure 11-41 compares the PAH emission 

indices of different engines when the base fuel or fleet fuels were used. The figure shows that the CJ610-

8ATJ and AE3007A1 series engines had highest PAH emission indices. The CFM56 model engines, on 

the other hand, emitted the least particles with surface-bound PAHs. Note that the test-average emission 

index is an overall measure of the emissions for all power conditions. The red color points in the figure 

are the test-averaged fuel flow rates for individual tests, which were determined by the power log during 

the tests. A higher test-average PAH emission index with lower test-average fuel flow rate implies a 

poorer combustion efficiency for an engine over the range of power conditions evaluated. 

Also shown for comparison in Table 11-6 are the equivalent PAH EIs obtained from the quartz filter timeintegrated sampling. Table 11-6 shows that the two data sets somewhat agree for the CFM56 series 

engines during some tests, but not for the others. Of the data presented, the quartz filter data are 

considered to be underestimated due to the lack of information on the unresolved compounds by the GCMS analysis, as discussed in Section 13. 

224
 

 

 

 

 

Table 11-6. Comparison between the PAH Emission Indices Obtained by the PAS 2000 

Measurements and the Quartz Filter Integrated Sampling 

APEX Test Engine 

Model Fuel 

Average 

Fuel Flow 

(kg/h) 

PAH Emission Index (mg/kg fuel) 

PAS 2000a Quartz filter 

analysisb 

EPA-1* 785 Fail 

EPA-2 Base 770 0.0650 0.0696 

NASA-1* Fuel 635 Fail 

NASA-1a 1559 0.225 

1 EPA-3 CFM56-2C1 797 Fail 0.104 

NASA-2 Hi-Sulfur 1279 Fail 

NASA-3 1277 Fail 

NASA-4 Hi- 1197 0.0560 

NASA-5 Aromatic 1244 0.0927 

T1 

CFM56-7B24 

1264 0.196 

0.00997 

T4 1264 0.253 

2 

T2 1201 0.479 

0.0243 

T3 CFM56-3B 1199 0.752 

T1* series 1352 1.53 

T11 1161 0.205 0.154 

T2 

CJ610-8ATJ 

618 1.67 

T5 Fleet 566 1.93 

T3 

AE3007A1E 

523 1.94 

0.123 

3 T4 554 1.94 

T10 AE3007A1/1 550 0.802 

T6 

P&W 4158 

2344 0.564 

0.00807 

T7 2968 0.598 

T8 

RB211-535E 

2087 Fail 

T9 2473 Fail 0.179 

* indicates the tests with high cross wind in background 

a. The PAH EI data shown here were obtained from the measurement by the PAS 2000 with no background correction. 

b. The quartz filter data shown here were after background and backup-filter correction. 

225
 

0 

500 

1000 

1500 

2000 

2500 

3000 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

1.6 

1.8 

2.0 

Average Fuel Flow Rate (kg/h) 

Average PAH Emission Index (mg/kg fuel) 

Emission Index 

Fuel Flow Rate 

CFM56-2C CFM56-7B CFM56-3B CJ610-8ATJ AE3007-A1/1 P&W 4158 

Figure 11-41. Comparison of the average PAH emission indices obtained from the tests with 

different types of jet engines. 

226
 

 

12. Gas-Phase Chemical Composition 

The gaseous emission samples were collected in both the plume and background sampling system 

during the APEX tests on a time-integrated basis using SUMMA canisters and DNPH cartridges. The 

samples were then analyzed by EPA Method TO-15 for analysis of the SUMMA samples and Method TO11A for the DNPH samples. The analytical results from these plume and background samples were used 

to derive the background corrected EIs for the individual non-methane volatile organic compounds 

(NMVOCs) and carbonyls in the gaseous engine emissions. The test results used in investigating 

gaseous emissions from different engines in this section were: EPA-2 of APEX-1 for the CFM56-2C1, 

T1&4 of APEX-2 for the CFM56-7B24, T2&3 of APEX-2 for the CFM56-3B series, T3&4 of APEX-3 for the 

AE3007-A1E, T6&7 of APEX-3 for the P&W 4158, and T9 of APEX-3 for the RB211-535E4-B engine. The 

gaseous emissions from a total of six different engine types were studied here. 

The emission indices of individual NMVOCs and carbonyl compounds obtained from the SUMMA and 

DNPH sampling for different engines are summarized in Table 12-1 and Figure 12-1, and Table 12-2 and 

Figure 12-2, respectively. Table 12-3 and Figure 12-3 compare the EI sums of VOCs and carbonyls for 

the different engines. The tables show that the P&W 4158 engine had emission indices of 703 mg/kg for 

NMVOCs and 729 mg/kg for carbonyls. These values are the highest among all the engines tested. The 

AE3007A1E engine produced the least amount of speciated gaseous pollutants and its emission indices 

were 258 mg/kg for NMVOCs and 287 mg/kg for carbonyls. Note that the ratio of NMVOCs to carbonyls 

was close to 1 for the CFM56-2C1, CFM56-7B24, CFM56-3B, AE3007-A1E, and P&W 4158 engines 

despite the difference in engine technology. The RB211-535E4-B engine, on the other hand, had higher 

NMVOC pollutants compared to carbonyls. The NMVOCs accounted for 57 percent of the total speciated 

gas phase pollutants for the CFM56-3B and 69 percent of the total gaseous pollutants for the RB211. 

The individual gaseous compounds emitted from the six different engines are compared in Figure 12-4. 

The figure shows that the gaseous emissions primarily consisted of formaldehyde (EI = 120-360 mg/kg or 

16-28 percent of total gaseous emissions), ethylene (41-246 mg/kg, 8-23%), acetaldehyde (38-126 

mg/kg, 5-13%), acetylene (28-128 mg/kg, 5-15%), propylene (9-86 mg/kg, 2-8%), and glyoxal (0-112 

mg/kg, 3-8%), with significant quantities of acrolein (0-38 mg/kg, <4%), benzene (0-25 mg/kg, <3%), 1,3-

butadiene (2-31 mg/kg, <3%), and toluene (3-10 mg/kg, <1%). A slight difference in the speciated 

gaseous emissions was seen for the AE3007-A1E engine, which had no glyoxal in the emissions, but 

instead contained 15 percent acetone (82 mg/kg) and 6 percent ethane (33 mg/kg). Formaldehyde, 

acetaldehyde, benzene, acrolein, toluene, and 1,3-butadiene are some of the compounds considered as 

hazardous air pollutants by EPA in the Clean Air Act. 

The above discussion was based on the gaseous compounds that were identified and quantified by the 

analytical instruments. Unresolved compounds made up about 16-42 percent of the total NMVOC (as 

227
 

 

 

 

 

 

 

 

 

 

 

 

 

ppmC) and carbonyl (as formaldehyde) compounds shown by gas chromatography, depending on the 

engine tested. 

Table 12-1.	 	 Emission Indices of Individual VOCs Obtained by SUMMA Sampling for Different 

Engines 

Engine CFM56-

2C1 

CFM56-

7B24 CFM56-3B AE3007A1E P&W 4158 RB211-

535E4B 

APEX APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

Test EPA-2 T1&4 T2&3 T3&4 T6&7 T9 

Gaseous Compound mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg 

Ethylene 219 92.7 123 40.6 246 194 

Acetylene 103 107 119 28.3 105 128 

Ethane 9.05 10.8 32.8 15.0 10.7 

Propylene 66.4 75.4 86.3 8.99 86.8 61.7 

Propane 2.53 2.09 25.9 0.944 1.10 

Isobutane 0.0778 0.265 6.23 

Isobutene/1-Butene 18.1 23.3 31.1 32.1 20.9 

n-Butane 0.316 15.4 

trans-2-Butene 1.44 2.53 2.67 2.68 1.86 

cis-2-Butene 1.15 1.62 1.95 2.63 2.01 

3-Methyl-1-butene 0.453 0.845 2.99 1.98 

Isopentane 2.94 2.12 8.28 

1-Pentene 6.62 5.53 8.08 11.4 6.05 

2-Methyl-1-butene 2.69 2.61 1.38 3.04 1.91 

n-Pentane 2.90 5.48 0.270 0.539 

Isoprene 3.81 2.44 0.274 

trans-2-Pentene 1.31 0.978 0.880 1.51 1.00 

cis-2-Pentene 0.731 0.867 0.844 0.613 

2-Methyl-2-butene 0.453 0.786 0.328 

2,2-Dimethylbutane 2.82 0.908 2.96 0.109 

Cyclopentene 0.655 1.28 1.49 

4-Methyl-1-pentene 1.15 1.30 1.73 1.52 

Cyclopentane 0.0564 0.547 0.0912 

2,3-Dimethylbutane 0.0362 0.0113 

2-Methylpentane 0.884 2.98 

3-Methylpentane 2.63 

2-Methyl-1-pentene 0.917 0.435 0.421 0.698 0.466 

1-Hexene 2.88 4.99 5.08 0.145 7.98 5.34 

228
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Engine CFM56-

2C1 

CFM56-

7B24 CFM56-3B AE3007A1E P&W 4158 RB211-535E4B 

APEX APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

Test EPA-2 T1&4 T2&3 T3&4 T6&7 T9 

Gaseous Compound mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg 

n-Hexane 2.41 

trans-2-Hexene 0.398 0.475 0.567 0.441 

cis-2-Hexene 0.452 3.62 34.6 58.6 

Methylcyclopentane 1.01 0.301 

2,4-Dimethylpentane 0.557 

Benzene 25.5 22.5 5.54 24.7 21.9 

Cyclohexane 0.483 

2-Methylhexane 0.0564 1.23 0.604 0.588 

2,3-Dimethylpentane 0.564 0.310 

3-Methylhexane 1.03 1.21 

1-Heptene 3.31 3.27 4.07 2.33 

n-Heptane 0.290 0.684 4.68 2.61 2.13 

Methylcyclohexane 0.409 0.391 0.994 2.52 0.809 

2,3,4-Trimethylpentane 0.285 

Toluene 2.88 8.19 9.80 2.87 9.57 6.30 

2-Methylheptane 0.525 0.933 1.52 

3-Methylheptane 1.03 1.11 0.766 

1-Octene 1.83 1.24 

n-Octane 0.0655 1.69 1.86 4.11 0.882 

Ethylbenzene 2.22 2.36 0.603 2.57 1.25 

Styrene 3.47 4.59 4.49 3.34 2.23 

o-Xylene 2.95 2.72 0.704 2.49 0.34 

1-Nonene 1.41 2.02 1.92 2.50 1.40 

n-Nonane 0.197 1.65 2.02 0.905 

Isopropylbenzene 0.27 

α-Pinene 0.917 0.416 2.99 

n-Propylbenzene 1.06 1.38 1.20 0.466 

m-Ethyltoluene 0.622 2.22 2.57 0.402 4.60 2.03 

p-Ethyltoluene 1.15 1.49 2.33 0.294 

1,3,5-Trimethylbenzene 0.557 0.49 1.39 0.402 3.45 

o-Ethyltoluene 1.79 2.15 0.453 1.32 

1,2,4-Trimethylbenzene 1.08 5.57 6.05 9.46 3.63 

n-Decane 0.557 4.17 1.48 

229
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Engine CFM56-

2C1 

CFM56-

7B24 CFM56-3B AE3007A1E P&W 4158 RB211-535E4B 

APEX APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

Test EPA-2 T1&4 T2&3 T3&4 T6&7 T9 

Gaseous Compound mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg 

1,2,3-Trimethylbenzene 2.00 2.36 2.84 0.809 

m-Diethylbenzene 0.779 0.508 1.07 1.27 

p-Diethylbenzene 0.435 0.582 1.41 0.466 

1-Undecene 1.84 0.882 

n-Undecane 2.10 3.60 2.81 10.1 3.82 

1-Dodecene 1.68 3.08 1.20 

n-Dodecane 2.37 1.42 5.49 1.89 

n-Tridecane 2.06 

Dichlorodifluoromethane 0.272 0.0564 18.7 

Chloromethane 0.349 0.182 6.34 

Dichlorotetrafluoroethane 0.704 

1,3-Butadiene 7.11 24.6 30.6 1.69 25.3 18.4 

Acrolein 30.0 37.6 

Trichlorofluoromethane 0.109 10.8 

Acrylonitrile 0.634 

Dichloromethane 0.836 0.0790 1.06 

Trichlorotrifluoroethane 5.03 

1,1,1-Trichloroethane 0.805 

Carbon Tetrachloride 1.87 0.198 5.67 0.147 0.294 

m,p-Xylene 4.90 7.15 1.56 8.08 2.25 

230
 

231
 


Emission Index (mg/kg fuel) 

EPA2 T1&4 T2&3 T3&4 T6&7 T9 

APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

CFM56-2C1 CFM56-7B24 CFM56-3B AE3007A1E P&W 4158 RB211-

535E4B 

Ethylene Ethylene Ethylene Ethylene Ethylene Ethylene 

Acetylene Propylene Acetylene Acetylene 1-Butene 

Acetylene Acetylene 

Propylene 

Propylene 

Propylene 

Propylene 

Acrolein 

Acrolein 

Acetylene 

Ethane 

Benzene 

Benzene 

Benzene 

Benzene 

1-Butene 

cis-2-Hexene 

cis-2-Hexene 

1-Butene 

1,3-Butadiene 

1,3-Butadiene 

1,3-Butadiene 

1,3-Butadiene 

Propane 

Ethylene 800 Ethane 

Propane 

Isobutene/1-Butene 

n-Butane 700 cis-2-Butene 

Isopentane 

2-Methyl-1-butene 

Isoprene 600 cis-2-Pentene 

2,2-Dimethylbutane 

4-Methyl-1-pentene 

2,3-Dimethylbutane 500 3-Methylpentane 

1-Hexene 

trans-2-Hexene 

Methylcyclopentane 400 Benzene 

2-Methylhexane 

3-Methylhexane 

n-Heptane 

300 2,3,4-Trimethylpentane 

2-Methylheptane 

1-Octene 

Ethylbenzene 

200 Styrene 

1-Nonene 

Isopropylbenzene 

n-Propylbenzene 

100 p-Ethyltoluene 

o-Ethyltoluene 

n-Decane 

m-Diethylbenzene 

0 1-Undecene 

1-Dodecene 

n-Tridecane 

Chloromethane 

Acrolein 

Acrylonitrile 

Trichlorotrifluoroethane 

Carbon Tetrachloride 

Acetylene 

Propylene 

Isobutane 

1,3-Butadiene 

trans-2-Butene 

3-Methyl-1-butene 

1-Pentene 

n-Pentane 

trans-2-Pentene 

2-Methyl-2-butene 

Cyclopentene 

Cyclopentane 

2-Methylpentane 

2-Methyl-1-pentene 

n-Hexane 

cis-2-Hexene 

2,4-Dimethylpentane 

Cyclohexane 

2,3-Dimethylpentane 

1-Heptene 

Methylcyclohexane 

Toluene 

3-Methylheptane 

n-Octane 

m-Xylene/p-Xylene 

o-Xylene 

n-Nonane 

a-Pinene 

m-Ethyltoluene 

1,3,5-Trimethylbenzene 

1,2,4-Trimethylbenzene 

1,2,3-Trimethylbenzene 

p-Diethylbenzene 

n-Undecane 

n-Dodecane 

Dichlorodifluoromethane 

Dichlorotetrafluoroethane 

Trichlorofluoromethane 

Dichloromethane 

1,1,1-Trichloroethane 

Figure 12-1. Mass EIs of individual NMVOCs from SUMMA canister sampling. 
 

 

 

 

 

 

 

 

 

 

Table 12-2. Emission Indices of Individual Carbonyl Compounds Obtained by DNPH Sampling 

for Different Engines 

Engine CFM56-

2C1 

CFM56-

7B24 CFM56-3B AE3007A1E P&W 4158 RB211-

535E4B 

APEX APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

Test EPA-2 T1&4 T2&3 T3 T6&7 T9 

Gas Compound mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg 

Formaldehyde 268 232 231 117 357 130 

Acetaldehyde 90.3 95.8 76.4 69.8 126.4 38.3 

Acetone 11.4 16.8 1.61 82.4 

Propionaldehyde 7.37 10.4 9.55 7.81 16.6 6.64 

Crotonaldehyde 21.7 19.7 20.7 26.8 10.41 

Butyraldehyde 3.11 5.26 4.22 4.86 2.70 

Benzaldehyde 13.5 10.2 10.0 14.0 7.18 

Isovaleraldehyde 2.14 0.670 0.811 2.43 

Valeraldehyde 6.94 3.48 4.57 6.13 3.01 

o-Tolualdehyde 3.57 4.77 6.45 2.60 

m-Tolualdehyde 7.04 3.85 5.42 9.33 3.01 

p-Tolualdehyde 3.24 1.20 1.30 3.14 

Hexaldehyde 0.118 1.92 2.41 4.72 2.09 

2,5-Dimethylbenzaldehyde 4.72 0.986 

Diacetyl 1.71 

Methacrolein 11.8 9.73 7.56 11.4 3.06 

2-Butanone 5.35 3.86 5.12 4.36 

Glyoxal 29.8 44.8 40.2 112 40.7 

Acetophenone 12.4 3.95 

Methylglyoxal 25.2 7.00 5.01 23.7 9.80 

Octanal 1.57 2.63 0.811 

Nonanal 3.83 0.568 2.65 

232
 

233
 


Emission Index (mg/kg fuel) 

800 

700 

600 

500 

400 

300 

200 

100 

0 

EPA2 T1&4 T2&3 T3 T6&7 T9 

APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

CFM56-2C1 CFM56-7B24 CFM56-3B AE3007A1E P&W 4158 RB211-

535E4B 

Formaldehyde Formaldehyde Formaldehyde Formaldehyde Formaldehyde Formaldehyde 

Acetaldehyde 

Acetaldehyde 

Acetaldehyde 

Acetaldehyde Acetaldehyde 

Glyoxal 

Glyoxal 

Glyoxal 

Glyoxal 

Acetone Glyoxal 

Acetaldehyde 

Nonanal 

Octanal
 


Methylglyoxal
 


Acetophenone 

Glyoxal 

2-Butanone 

Methacrolein 

Diacetyl 

2,5-Dimethylbenzaldehyde 

Hexaldehyde 

p-Tolualdehyde 

m-Tolualdehyde 

o-Tolualdehyde 

Valeraldehyde 

Isovaleraldehyde 

Benzaldehyde 

Butyraldehyde 

Crotonaldehyde 

Propionaldehyde
 


Acetone
 


Acetaldehyde 

Formaldehyde 

 

Figure 12-2. 

Table 12-3. 

Mass EIs of individual carbonyl compounds from DNPH cartridge sampling. 

Comparison of NMVOC and Carbonyl Emission Indices for Different Engines 

Test EPA-2 T1&4 T2&3 T3&4 T6&7 T9 

APEX APEX-1 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

Engine CFM56-2C1 CFM56-

7B24 CFM56-3B AE3007A1E P&W 4158 RB211-

535E4B 

NMVOCs mg/kg 452 490 567 258 703 577 

Carbonyls mg/kg 521 479 432 287 729 263 

NMVOCs % 46.5 50.6 56.7 47.3 49.1 68.7 
 

Emission Index (mg/kg fuel)

1600

1400

1200

1000

800

600

400

200

0

452 490 567

258

703

577

521 479 432

287

729

263

EPA2 T1&4 T2&3 T3&4 T6&7 T9

APEX‐1 APEX‐2 APEX‐2 APEX‐3 APEX‐3 APEX‐3

CFM56‐2C1 CFM56‐7B24 CFM56‐3B AE3007A1E P&W 4158 RB211‐

535E4B

Carbonyls

NMVOCs

Figure 12-3. Emission indices of total NMVOCs and carbonyls for different engines. 

234
 

235
 


-

 

Emission Index (mg/kg fuel)

1500

1400

1300

1200

1100

1000

900

800

700

600

500

400

300

200

100

0

EPA2 T1&4 T2&3 T3&4 T6&7 T9

APEX‐1 APEX‐2 APEX‐2 APEX‐3 APEX‐3 APEX‐3

CFM56‐2C1 CFM56‐7B24 CFM56‐3B AE3007A1E P&W 4158 RB211‐535E4B

Ethylene

22.5%

Ethylene

23.1%

Ethylene

17.2% Ethylene

12.3%

Ethylene

9.6%

Acetylene

10.6% Acetylene

15.3%

Acetylene

7.3%

Acetylene

Acetylene 12%

11.1%

Propylene Propylene

7.3%

Propylene

6.1%

Propylene

Propylene 8.6%

7.8%

Formaldehyde

27.6%

Formaldehyde

15.5%

Formaldehyde

24.9%

Formaldehyde

21.5%

Formaldehyde

23.1%

Formaldehyde

24%

Acetone

15.1%

Glyoxal

7.8%

Glyoxal 4.6%

Glyoxal 4%

Glyoxal 4.8% Acetaldehyde

9.3% Acetaldehyde

Acetaldehyde

8.8%

Acetaldehyde

7.7%

Acetaldehyde

9.9%

Acetaldehyde

12.8%

cis-2 Hexene 

Ethylene Acetylene

Ethane Propylene

Propane Isobutane

Isobutene/1‐Butene 1,3‐Butadiene

n‐Butane trans‐2‐Butene

cis‐2‐Butene 3‐Methyl‐1‐butene

Isopentane 1‐Pentene

2‐Methyl‐1‐butene n‐Pentane

Isoprene trans‐2‐Pentene

cis‐2‐Pentene 2‐Methyl‐2‐butene

2,2‐Dimethylbutane Cyclopentene

4‐Methyl‐1‐pentene Cyclopentane

2,3‐Dimethylbutane 2‐Methylpentane

3‐Methylpentane 2‐Methyl‐1‐pentene

1‐Hexene n‐Hexane

trans‐2‐Hexene cis‐2‐Hexene

Methylcyclopentane 2,4‐Dimethylpentane

Benzene Cyclohexane

2‐Methylhexane 2,3‐Dimethylpentane

3‐Methylhexane 1‐Heptene

n‐Heptane Methylcyclohexane

2,3,4‐Trimethylpentane Toluene

2‐Methylheptane 3‐Methylheptane

1‐Octene n‐Octane

Ethylbenzene m‐Xylene/p‐Xylene

Styrene o‐Xylene

1‐Nonene n‐Nonane

Isopropylbenzene a‐Pinene

n‐Propylbenzene m‐Ethyltoluene

p‐Ethyltoluene 1,3,5‐Trimethylbenzene

o‐Ethyltoluene 1,2,4‐Trimethylbenzene

n‐Decane 1,2,3‐Trimethylbenzene

m‐Diethylbenzene p‐Diethylbenzene

1‐Undecene n‐Undecane

1‐Dodecene n‐Dodecane

n‐Tridecane Dichlorodifluoromethane

Chloromethane Dichlorotetrafluoroethane

Acrolein Trichlorofluoromethane

Acrylonitrile Dichloromethane

Trichlorotrifluoroethane 1,1,1‐Trichloroethane

Carbon Tetrachloride Formaldehyde

Acetaldehyde Acetone

Propionaldehyde Crotonaldehyde

Butyraldehyde Benzaldehyde

Isovaleraldehyde Valeraldehyde

o‐Tolualdehyde m‐Tolualdehyde

p‐Tolualdehyde Hexaldehyde

2,5‐Dimethylbenzaldehyde Diacetyl

Methacrolein 2‐Butanone

Glyoxal Acetophenone

Methylglyoxal Octanal

Nonanal

Figure 12-4. Comparison of EIs for individual gas phase species as produced by different engine 

types. 
This page intentionally left blank. 

236
 

13. Particle-Phase Chemical Composition 

The PM-phase chemical composition discussed in this study includes the inorganic elements and ions, 

elemental carbon, organic carbon, and organic compounds determined by analyzing the Teflon and 

quartz filter samples collected from the time-integrated sampling. Like the discussion of black carbon and 

PAH emissions, the emission indices reported here are without correction for sampling line particle losses 

because the fraction of species of the PM lost in the sampling line could not be determined from available 

data. Summary tables of experimental results for PM speciation and element EI can be found in Tables 

H-1 and H-2, respectively, in Appendix H. 

13.1 Element and Ion Emissions 

The Teflon filter samples were first subjected to trace elemental analysis by X-ray fluorescence (XRF). 

The samples were then extracted with HPLC-grade deionized water and the extracts were analyzed by 

ion chromatography (IC) for determination of sulfate, nitrate, and chloride in the PM collected on the 

filters. The Teflon filters were installed in both plume and background sampling systems, so that the 

background-corrected concentrations and emission indices for individual elements and ions were 

obtained for each test. The tests in this study for which the XRF and IC analyses were conducted are 

EPA-1, EPA-2, EPA-3 and NASA-4&5 of APEX-1, T1 to T4 of APEX-2, and T3&4, T6&7, T9, and T11 of 

APEX-3. In calculation of the element emission indices from the XRF analytical results, the reported 

uncertainties were used. Thus, the elements which had detected concentrations either less than their 

detection limits or less than three times their uncertainties were not reported. 

Although integrated filter sampling was conducted in the APEX-1 EPA-1 test, the results from this test 

were not used in the discussion of this section because of high background interference by crosswinds 

during this test. Furthermore, the total element and ion concentrations on the background Teflon filter for 

the APEX-3 T6&7 were extremely high. Since the PM mass collected on the background Teflon filter for 

this test was low (-0.016 mg), that filter may have been contaminated either in the field or in the 

laboratory. Therefore, this test was also excluded in the element and ion emission discussion. 

Various trace elements in the PM emissions are considered to originate from the presence of these 

elements in fuels, lubricating oils, engine wear and corrosion, sampling line, and fugitive dust. Table 13-1 

summarizes the total emission index of elements derived from the XRF analysis for each test. The engine 

type, fuel sulfur content, and test-average rated thrust and fuel flow rate are also presented in the table. 

The emission indices for individual elements are presented in stacked column format for each test in 

Figure 13-1. The blue columns in the figure represent the sulfur in PM, which clearly was the most 

abundant element for all the tests. The samples of APEX-2 T1 test contained notable amounts of Si, 

probably due to dust contamination resulting from the resuspension of concrete cuttings left over from the 

drilling of holes in the tarmac. 

237
 
 

 

Table 13-1. Total Elemental Emission Index Derived from the XRF Analyses 

APEX Test Engine 

Fuel 

Sulfur 

(ppm) 

Time-weighted 

Engine Powera 

(%) 

Fuel Flow 

(kg/h) 

Total Metal 

Emission Index 

(mg/kg fuel) 

EPA-2 409 18.8 770 10.8 

1 EPA-3 CFM56-2C1 1639 20.4 797 27.5 

NASA-4&5 553 35.7 1221 12.0 

T1 

CFM56-7B24 

132 30.1 1264 6.33 

2 T4 412 30.1 1264 13.5 

T2&3 

CFM56-3B series 

279 31.0 1200 10.1 

T11 400 31.1 1161 12.8 

3 T3&4 AE3007A1E 300 41.1 537 7.51 

T9 RB211-535E4-B 300 34.2 2473 6.92 

a

 Time-weighted average (TWA) thrust calculated over entire test period. 

30 

CFM56-2CCFM56-2CCFM56-2CCFM56-7BCFM56-7BCFM56-3BCFM56-3B

AE3007A1E

RB211-535E4 

APEX-1 

EPA2 

APEX-1 

EPA3 

APEX-1 

NASA4&5 

APEX-2 T1APEX-2 T4 APEX-2 

T2&3 

APEX-3 

T11 

APEX-3 

T3&4 

APEX-3 T9 

Tl I Te 

Sb In Ag

Br Zn Cu 

Ni Fe Mn 

Cr Ti Ca 

K Cl S 

P Si Mg 

S 

S 

S 

Si 

S 

S 

S 

S 

S 

S 

Fe 

Mg 

Figure 13-1. Elemental emission indices for each test. Element Emission Index (mg/kg fuel) 25 

20 

15 

10 

5 

0 

238
 

239
 

The results of the tests with the same engine and same fuel were averaged and the elemental emissions 

from different engines compared in Table 13-2 and Figure 13-2. The element emission indices for 

different engines were obtained with base fuel or fleet fuel and were plotted in stacked columns in the 

figure. The results show that the total element emissions produced from the CFM56 engines were 

relatively higher than the total element emissions from the AE3007-A1E and RB211-535E4-B engines. 

The table shows that about 2 to 7 percent of the total PM mass were the elements for these engines. The 

mass percentage of sulfur in the total elements detected for each test was also provided in the figure, 

indicating that over 80 percent of the elemental mass was sulfur for all five engines compared except for 

the AE3007A1E engine (54% sulfur). 

Table 13-2. Elemental Emission Indices for Different Engines 

Engine 

Time-Weighted 

Engine Powera 

(%) 

Fuel Flow 

(kg/h) 

PM EI 

(mg/kg) 

Total 

Metal EI 

(mg/kg) 

Metal/PM 

(%) 

Sulfur EI 

(mg/kg) 

S/Metal 

(%) 

CFM56-2C1 18.8 770 305 10.8 3.54 9.54 88.3 

CFM56-7B24 30.1 1264 9.94 8.05 81.0 

CFM56-3B 31.0 1200 267 11.5 4.30 10.1 88.4 

AE3007A1E 41.1 537 116 7.51 6.48 4.03 53.7 

RB211-535E4-B 34.2 2473 384 6.92 1.80 6.15 88.9 

a. TWA calculated for all tests conducted. 

14
 


12
 


10
 


8
 


6
 


4
 


2
 


0
 


I Te Sb In Ag Br Zn 

Cu Ni Fe Mn Cr Ca K 

Cl S P Si Mg 

88% S 

81% S 

88% S 

54% S 

89% S 

Mg Si 

Fe 

I 

CFM56-2C CFM56-7B CFM56-3B AE3007A1E RB211-535E4 

Figure 13-2. Comparison of elemental emission indices for different engines. Element Emission Index (mg/kg fuel) 
The sulfur detected in PM samples originated from the jet fuels used in the tests. Therefore the highsulfur fuel was expected to produce a higher elemental sulfur emission index. Table 13-3 provides the 

sulfur emission index results and the sulfur contents in the fuels. Table 13-3 indicates that the primary 

element in the PM emissions was sulfur regardless of fuel type. The sulfur content in the total detected 

elements was 88 percent for base fuel (APEX-1 EPA2), 95 percent for high sulfur fuel (APEX-1 EPA3), 

and 93 percent for high aromatic fuel (APEX-1 NASA-4&5). The sulfur emission index for high sulfur fuel 

was 26.2 mg/kg, which was 2.3 times as much for high aromatic fuel and 2.7 times as much for base fuel. 

It is not surprising that the high sulfur fuel had the highest sulfur emission index. The conversion of fuel 

sulfur into particulate was also calculated and presented in the table, indicating that about 2 to 3 percent 

of fuel sulfur was converted into sulfate as part of particulate matter emissions. By plotting the sulfur 

emission indices derived from the XRF analytical results for the CFM56 engines as a function of fuel 

sulfur content, Figure 13-3 shows that the correlation between the emission index of sulfur in PM and the 

fuel sulfur content can be approximately expressed by a linear equation with a correlation coefficient (r2

) 

of 0.93. 

The water soluble ion emission indices derived from the IC analysis of the Teflon filter samples for various 

tests are presented in Table 13-4 and Figure 13-4. Four ions, K+

, NH4

+

, Cl-, and SO4

-2, were reported, of 

which SO4

-2 and NH4+

 were the two primary inorganic ions comprising 90 percent of the total ion mass. 

The table also presents the S(IV) to S(VI) conversion calculated from the known amount of sulfur in fuel 

and the measured sulfate EI. Also shown for comparison in Table 13-4 are similar results from the 

European PartEmis program (Katragkou et al., 2004) and the landmark study by Schumann et al. (2002). 

The IC results show that approximately two to four percent of the sulfur in the fuel was converted to water 

soluble particulate sulfate, consistent with the data of Katragkou et al. (2004) and Schumann et al. (2002). 

Also, comparing this value to the sulfur conversion values shown in Table 13-3, the fuel sulfur conversion 

efficiency determined by IC was either slightly more or less than that measured by XRF, indicating 

differences in the two analytical methods. 

Table 13-5 and Figure 13-5 compare the average EIs of individual ions among five different engines. The 

total ion emission indices for all five engines range from 30-40 mg/kg fuel. For the three CFM56 engines, 

SO4

-2, had about 71 percent of total ion mass. The AE3007-A1E and RB211-535E4-B engines had 63 

and 53 percent SO4

-2, respectively. 

Table 13-6 presents the SO4

-2 ion EIs obtained for the CFM56 engine with different fuel compositions. 

Like sulfur detected by XRF, the emission index of SO4

-2 was linearly correlated to the sulfur content in 

fuel as shown in Figure 13-6. The relation between SO4

-2 EI and fuel sulfur content can be approximately 

described by a linear equation with an r2 of 0.90. 

240
 

 

 

0 500 1000 1500 2000 

Sulfur in Fuel (ppm) 

y = 0.0136x + 4.4952

R2 = 0.9258 

0 

5 

10 

15 

20 

25 

30 

Sulfur Emission Index (mg/kg fuel) 

Table 13-3. Sulfur Emission Indices for Individual Tests as Determined from the XRF Analyses 

and Their Associated Fuel Sulfur Contents 

APEX Test Engine 

Sulfur 

in Fuel 

(ppm) 

Sulfur EI 

(mg/kg) 

S/Metal 

(%) 

Sulfur 

Conversion 

(%) 

EPA2 409 9.54 88.3 2.33 

1 EPA3 CFM56-2C1 1639 26.2 95.3 1.60 

NASA-4&5 553 11.2 93.3 2.02 

T1 

CFM56-7B24 

132 3.11 49.1 2.35 

2 T4 412 13.0 95.9 3.15 

T2&3 CFM56-3B 279 9.21 91.2 3.30 

3 T11 series 400 11.1 86.3 2.77 

Figure 13-3. Correlation of sulfur emission index with fuel sulfur content for CFM56 engines. 

241
 

 

 

 

 

 

 

 

100
 


90
 
 SO4 

Cl 

NH4 

K 

APEX-1 APEX-1 APEX-1 APEX-2 APEX-2 APEX-2 APEX-3 APEX-3 APEX-3 

EPA2 EPA3 NASA4&5 T1 T4 T2&3 T11 T3&4 T9 

Ion Emission Index (mg/kg) 

80 

70 

60 

50 

40 

30 

20 

10 

0 

CFM56-2CCFM56-2CCFM56-2CCFM56-7BCFM56-7BCFM56-3BCFM56-3B

AE3007A1E

RB211-535E4 

Table 13-4. Water Soluble Ion Emission Indices Derived from the IC Analyses for Each Test 

APEX Test Engine 

Fuel 

Sulfur 

(ppm) 

TimeWeighted 

Engine 

Power (%) 

TimeWeighted 

Fuel Flow 

(kg/h) 

Emission Indices 

Sulfur 

Conversion 

(%) Total Ions 

(mg/kg) 

K 

(mg/kg) 

NH4 

(mg/kg) 

Cl 

(mg/kg) 

SO4 

(mg/kg) 

1 

EPA2 

CFM56-

2C1 

409 18.8 770 29.4 2.98 5.46 20.9 1.71 

EPA3 1639 20.4 797 86.0 5.54 10.5 69.9 1.42 

NASA4&5 553 35.7 1221 40.0 1.91 5.69 32.4 1.95 

2 

T1 CFM56-

7B24 

132 30.1 1264 25.8 8.51 17.3 4.37 

T4 412 30.1 1264 53.0 13.8 39.2 3.17 

T2&3 CFM56-

3B series 

279 31.0 1200 36.5 2.38 6.69 27.4 3.28 

3 

T11 400 31.1 1161 42.0 13.6 28.4 2.37 

T3&4 AE3007-

A1E 300 41.1 537 40.7 15.1 25.6 2.85 

T9 RB211-

535E4-B 300 34.2 2473 31.8 3.85 8.24 3.01 16.7 1.86 

PartEmis (Katragkov et al., 2004) 2.30a 

Schumann et al., 2002 3.30b 

a Low pressure stage of combustor + hot end simulator at modern cruise power. 

b CFM56-3B1 engine at cruise altitude. 

Figure 13-4. Water-soluble ion emission indices for each test. 

242 
Table 13-5. Water Soluble Ion Emission Indices for Different Engines 

Engine Powera 

(%) 

Fuel Flowa 

(kg/h) 

PM EI 

(mg/kg) 

Total Ion EI 

(mg/kg) 

Ions/PM 

(%) 

SO4 EI 

(mg/kg) 

SO4/Ions 

(%) 

CFM56-2C1 18.8 770 305 29.4 9.64 20.9 71.3 

CFM56-7B24 30.1 1264 39.4 28.3 71.7 

CFM56-3B 31.0 1200 267 39.3 14.7 27.9 71.2 

AE3007-A1E 41.1 537 116 40.7 35.2 25.6 62.9 

RB211-535E4-B 34.2 2473 384 31.8 8.29 16.7 52.6 

a

 TWA calculated for all tests conducted. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

Ion Emission Index (mg/kg fuel) 

SO4 

Cl 

NH4 

K 

71% SO4 

72% SO4 71% SO4 

63% SO4 

53% SO4 

CFM56-2C CFM56-7B CFM56-3B AE3007A1E RB211-535E4 

Figure 13-5. Comparison of water-soluble ion emission indices for different engines. 

243
 

 

y = 0.0333x + 15.469 

R2

 = 0.9004 

0 

10 

20 

30 

40 

50 

60 

70 

80 

Sulfate Emission Index (mg/kg fuel) 

0 200 400 600 800 1000 1200 1400 1600 1800 

Sulfur in Fuel (ppm) 

Table 13-6. Sulfate Emission Indices from the IC Analyses and Their Fuel Sulfur Contents 

APEX Test Engine Fuel Sulfur 

(ppm) 

SO4 EI 

(mg/kg) 

S/Ions 

(%) 

EPA2 409 20.9 71.3 

1 EPA3 CFM56-2C1 1639 69.9 81.3 

NASA-4&5 553 32.4 81.0 

T1 

CFM56-7B24 

132 17.3 67.0 

2 T4 412 39.2 74.0 

T2&3 CFM56-3B 279 27.4 75.2 

3 T11 series 400 28.4 67.7 

Figure 13-6. Correlation of SO4 emission index with fuel sulfur content for CFM56 engines. 

13.2 Organic and Elemental Carbon Emissions 

The quartz filters collected from the integrated sampling were first analyzed by the EC/OC analyzer to 

determine the organic and elemental carbon content in the PM samples, and then analyzed by GC/MC to 

determine the semivolatile organic compounds in PM. Accurate collection and determination of particulate 

organic material on quartz filters was complicated by the fact that gas phase organic compounds may be 

adsorbed by the quartz filters during sampling, resulting in overestimate of the actual concentrations. This 

sampling artifact was accounted for by placing a backup quartz filter(s) behind the Teflon filter in the 

sampling array using an approach developed by Turpin et al. (1994). No artifact correction was made for 

244
 

the Teflon filters. The organic carbon was then obtained by subtracting the amount of OC found on the 

quartz filter located downstream of the Teflon filter from the amount found on the primary quartz filter. The 

elemental carbon is always considered as non-volatile particulate, and therefore no backup filter 

correction was needed in the elemental carbon emission index calculation. Like Teflon filter sampling, the 

quartz filters were installed in both the plume and background systems so that the background could be 

corrected. For comparison, the emission indices of OC and semivolatile organic compounds were 

reported both with background and backup correction and with only the background corrected. 

Table 13-7 summarizes the results of organic and elemental carbon emission indices derived from the 

analysis of quartz filter samples. The tests shown are EPA-3, NASA-2&3, and NASA-4&5 for APEX-1; T1, 

T4 and T2&3 for APEX-2; and T3&4, T9 and T11 for APEX-3. For the EPA-2 test, both plume front and 

background quartz filters were found broken. Therefore the EPA-2 plume quartz filter samples were not 

analyzed for organic and elemental carbon content. However, these samples were solvent-extracted and 

analyzed by GC/MS for organic speciation which will be discussed later. High background OC and EC 

content was also found for APEX-3 T3&4. As a result, only the uncorrected OC EI was reported. For 

backup and background-corrected samples, the emission indices obtained in this study ranged from 37-

83 mg/kg of fuel burned for OC and 21-98 mg/kg of fuel burned for EC, depending on the test conditions. 

The EC/OC ratio ranged from 0.3 to 2. 

Table 13-7. Organic and Elemental Carbon Emission Indices for Each Test 

APEX Test Engine 

TimeWeighted 

Engine 

Power 

(%) 

TimeWeighted 

Average 

Fuel Flow 

(kg/h) 

Background and 

Backup Corrected 

Background 

Corrected Only 

Without Any 

Correction 

OC 

(mg/kg) 

ECa 

(mg/kg) 

EC/OC 

Ratio 

OC 

(mg/kg) 

ECa 

(mg/kg) 

OC 

(mg/kg) 

EC 

(mg/kg) 

NASA-2&3 18.8 770 83.2 21.1 0.253 100 21.1 179 27.9 

1 EPA-3 CFM56-2C1 20.4 797 37.1 26.1 0.703 21.1 26.1 188 40.2 

NASA-4&5 35.7 1221 50.7 32.4 0.640 80.7 32.4 137 48.2 

T1 

CFM56-7B24 

30.1 1264 82.0 28.1 0.342 132 28.1 225 37.4 

2 T4 30.1 1264 42.2 25.1 0.595 76.8 25.1 176 33.5 

T2&3 CFM56-3B 31.0 1200 50.4 91.9 1.82 69.3 91.9 120 95.4 

T11 series 31.1 1161 54.7 98.4 1.80 77.5 98.4 113 98.4 

3 T3&4 AE3007-A1E 41.1 537 - 39.2 - - 39.2 118 63.4 

T9 RB211-

535E4-B 34.2 2473 39.2 27.5 0.700 57.0 27.5 89.9 27.5 

a. Quartz filters will not adsorb EC, therefore the EC data before and after backup correction should be the same. 

By averaging the emission indices of the tests with the same engine type, the OC and EC EIs for different 

engine models are compared in Table 13-8. The EI results for the CFM56-2C1 are not shown in the table 

due to the high background effect of crosswinds. For APEX-3 T3&4 for the AE3007-A1E engine, the 

background quartz filter had high OC contamination, resulting in zero OC EIs after backup and/or 

background corrections. 

245
 
 

 

 

Table 13-8. Organic Carbon and Elemental Carbon Emission Indices for Different Engines 

Engine 

TimeWeighted 

Engine 

Powera 

(%) 

TimeWeighted 

Fuel 

Flow 

(kg/h) 

Background and 

Backup Corrected 

Background 

Corrected Only 

Without Any 

Correction 

OC 

(mg/kg) 

ECb 

(mg/kg) 

OC 

(mg/kg) 

ECb 

(mg/kg) 

OC 

(mg/kg) 

EC 

(mg/kg) 

CFM56-7B24 30.1 1264 62.1 26.6 105 26.6 200 35.4 

CFM56-3B 31.0 1200 52.5 95.2 73.4 95.2 116 96.9 

AE3007-A1E 41.1 537 - 39.2 - 39.2 118 63.4 

RB211-535E4-B 34.2 2473 39.2 27.5 57.0 27.5 89.9 27.5 

a. TWA was calculated from all the power levels tested for each test. 

b. Quartz filters do not adsorb EC, therefore the EC data before and after backup filter correction should be the same. 

Figure 13-7 compares the OC and EC emission indices obtained from different engines. Figure 13-7(a) 

shows that, among the engines tested, the newer CFM56-7B24 engine produces the highest organic 

carbon emissions and the RB211-535E4 engine had lowest OC EI. The figure also shows that the effects 

of backup and background correction on the emission index were different from one engine to another. 

For elemental carbon emissions as shown in Figure 13-7(b), the highest EI was obtained from the 

CFM56-3B engine and the CFM56-2C had lowest EC EI. 

13.3 Particle-Phase Organic Compounds 

The identification and quantification of trace organic compounds collected on the APEX quartz filter 

samples were done using two approaches. After the APEX-1 campaign, the amount of organic carbon 

collected on each individual quartz filter ranged between 0.01 and 0.16 mg, much below 1 mg of OC 

required in order to use the solvent-extraction and GC/MS method for appropriate organic compound 

speciation. As a result, the quartz filter samples obtained during APEX-2 from the same engines were 

composited to increase the amount of OC for solvent extraction analysis. Thus, the corresponding 

samples from T2 and T3 tests for the CFM56-3B tests were composited and labeled as T2&3. Also the 

composite samples from T1 and T4 for the -7B24 model CFM56 were labeled as T1&4. In the case of 

APEX-3, the more sensitive thermal desorption GC/MS (TD/GC/MS) method was used in lieu of solvent 

extraction for all samples collected. 

The emission indices of individual organic compounds were calculated for the different tests. Both the 

quartz-filter artifact correction (backup correction) and background correction were conducted during the 

emission index calculation. The results of emission indices with both backup and background correction 

and the results that were background corrected but without backup-quartz-filter correction are all 

summarized in Table H-1 in Appendix H. The total emission indices for individual organic groups and for 

all the organic compounds detected are also presented in the tables. 

246
 

CFM56-2C CFM56-7B CFM56-3B AE3007A1E RB211-535E4 

CFM56-2C CFM56-7B CFM56-3B AE3007A1E RB211-535E4 

0 

50 

100 

150 

200 

250

Emission Index (mg/kg fuel) 

OC BK+Bkup Corrected 

OC BK Corrected 

OC Without Correction 

(a) 

0 

20 

40 

60 

80 

100 

120 

Emission Index (mg/kg fuel) 

EC BK Corrected 

EC Without Correction 

(b) 

Figure 13-7. Comparison of OC and EC emission indices for: (a) organic carbon; and 

(b) elemental carbon. 

247
 

Figure 13-8 shows the contribution of individual organic compounds to the total speciated particle-phase 

EI for different engines. The results were corrected for both quartz filter sampling artifact and background. 

The test number and sampling campaign are presented in the figure. In general, the figure shows that 

AE3007-A1E and CFM56-3B were the two engines having the highest emission indices of total speciated 

organics. Both the P&W 4158 and CFM56-7B24 produced the lowest EI for semi-volatile organic 

compounds. However, the samples from APEX-2 T1&4 for the CFM56-7B24 engine were analyzed by 

solvent extraction, which is considered less sensitive than the thermal desorption analysis used for the 

APEX-3 engine samples. Therefore, the lower emission indices of speciated organic compounds for 

APEX-2 T1&4 could be attributable to the method of analysis used. 

Figure 13-9 compares the emission indices of classes of organic compounds for different engines. The 

percentage value for each group is also presented in the figure. Regardless of the difference in engine 

type, the n-alkanes and PAHs were the primary compounds observed. For the AE3007-A1E engine, the 

total emission index of organic compounds was 293 ug/kg of fuel burned, of which about 58 percent was 

n-alkanes and 42 percent was PAHs. 

-

-

350 

300 

250 

Emission Index (ug/kg) 200 

150 

100 

50 

0 

EPA2 T1&4 T11 T3&4 T6&7 T9 

APEX-1 APEX-2 APEX-3 APEX-3 APEX-3 APEX-3 

Coronene 17A(H)-21B(H)-Hopane 

17B(H)-21A(H)-30-Norhopane 17A(H)-22,29,30-Trisnorhopane 

ABB-20R-C29-Ethylcholestane ABB-20R-C28-Methylcholestane 

AAA-20S-C27-Cholestane ABB-20R-C27-Cholestane 

Benzo[ghi]perylene Indeno[1,2,3-cd]pyrene 

Benzo(e)pyrene Benzo[b]fluoranthene 

Benzo[k]fluoranthene Benzo[a]anthracene 

Chrysene Pyrene 

Retene Fluoranthene 

Anthracene Phenanthrene 

Fluorene Dibenzofuran 

Acenaphthylene 2,6-Dimethylnaphthalene 

1,3 Dimethylnaphthalene 2,7 Dimethylnaphthalene 

2-Methylnaphthalene 1-Methylnaphthalene 

Series34 Naphthalene 

Nonadecylcyclohexane Dodecylcyclohexane 

Naphthalic Anhydride Squalene 

Phytane 2-Methylnonadecane 

n-Heptatriacontane (n-C37) n-Hexatriacontane (n-C36) 

n-Pentatriacontane (n-C35) n-Tetratriacontane (n-C34) 

n-Tritriacontane (n-C33) n-Dotriacontane (n-C32) 

n-Hentricontane (n-C31) n-Triacontane (n-C30) 

n-Nonacosane (n-C29) n-Octacosane (n-C28) 

n-Heptacosane (n-C27) n-Hexacosane (n-C26) 

n-Pentacosane (n-C25) n-Tetracosane (n-C24) 

n-Tricosane (n-C23) n-Docosane (n-C22) 

n-Heneiicosane (n-C21) n-Nonadecane (n-C19) 

n-Octadecane (n-C18) n-Heptadecane (n-C17) 

n-Hexadecane (n-C16) n-Pentadecane (n-C15) 

n-Tetradecane (n-C14) n-Tridecane (n-C-13) 

n-Dodecane (n-C12) n-Undecane (n-C11) 

Pyrene 

Pyrene 

Fluor 

anthene 

Fluor 

anthene 

Squalene 

n-Nonacosane 

Pyrene 

Figure 13-8. Relative contribution of individual organic compounds to the total speciated 

particle-phase EI. 

248
 

Emission Index (ug/kg) 

350 

300 

250 

200 

150 

100 

50 

0 

PAH 

Cyclohexanes 

Oxy PAH 

Alkenes 

Branched alkanes 

n-alkanes 

63.1% 

9.3% 

24.5% 

56.6% 

43.4% 

30.6% 

12.9% 

55.1% 

42.0% 

58.0% 

50.1% 

33.9% 

66.1% 

EPA2 T1&4 T11 T3&4 T6&7 T9 

APEX-1 APEX-2 APEX-3 APEX-3 APEX-3 APEX-3 

CFM56-2C CFM56-7B CFM56-3B AE3007 P&W 4158 RB211 

 

Figure 13-9.	 	 Relative contribution of classes of organic compounds to the total speciated 

particle-phase EI. 

The effects of the correction for quartz filter sampling artifact on the emission indices of individual organic 

compounds were investigated by comparing the emission index results of individual organic groups 

before and after backup correction as presented in Figure 13-10(a) and (b), respectively. After correction, 

most oxy PAH and phthalates on the plume front quartz filters were significantly reduced or even 

eliminated for all engines. 

The effect of background correction was further investigated in Figure 13-11, where the emission index 

results of n-alkanes and PAH obtained without any correction, with background correction only and with 

both backup and background correction were compared. The results for n-alkanes are presented in 

Figure 13-11(a) and Figure 13-11(b) provides the PAH results. The figures show that the background 

quartz filters contained high n-alkanes, and therefore the EI values for alkanes were substantially reduced 

by background correction. For the PAHs, only the APEX-3 T3&4 and T9 tests had a high background. 

Both Figure 13-10 and 13-11 underscore the need for a valid ambient background correction for these 

types of chemical analyses. 

249
 

250
 


Emission Index (ug/kg fuel) 

800
 

700
 

600
 

500
 

400
 

300
 

200
 

100
 

0
 

PAH 

Steroids 

Cyclohexanes 

Oxy PAH 

Phthalate 

Alkenes 

Branched alkanes 

n-alkanes 

(a) 

EPA1
 EPA2 EPA3 T1&4 T2&3 T3&4 T6&7 T9 T11
 

APEX-1
 APEX-1
 APEX-1
 APEX-2
 APEX-2
 APEX-3
 APEX-3
 APEX-3
 APEX-3
 

800
 

700
 

	 Emission Index (ug/kg fuel) 600
 

500
 

400
 

300
 

200
 

100
 

0
 

PAH 

Steroids 

Cyclohexanes 

Oxy PAH 

Phthalate 

Alkenes 

Branched alkanes 

n-alkanes 

(b) 

EPA1
 EPA2 EPA3 T1&4 T2&3 T3&4 T6&7 T9 T11
 

APEX-1
 APEX-1
 APEX-1
 APEX-2
 APEX-2
 APEX-3
 APEX-3
 APEX-3
 APEX-3
 

Figure 13-10.	 Effects of quartz-filter sampling-artifact correction on emission indices of individual 

organic groups: (a) before backup correction; and (b) after backup correction. 
251
 


Emission Index (ug/kg fuel) Emission Index (ug/kg fuel) 

1200 

1000
 

800
 

600
 

400
 

200
 

0 

No Correction 

BK Corrected 

BK&Bkup Corrected 

(b) PAH 

No Correction 

BK Corrected 

BK&Bkup Corrected 

(a) n-alkanes 

EPA1 EPA2 EPA3 T1&4 T2&3 T3&4 T6&7 T9 T11 

APEX-1
 APEX-1
 APEX-1
 APEX-2
 APEX-2
 APEX-3
 APEX-3
 APEX-3
 APEX-3
 

250
 

200
 

150
 

100
 

50
 

0 

EPA1 EPA2 EPA3 T1&4 T2&3 T3&4 T6&7 T9 T11 

APEX-1
 APEX-1
 APEX-1
 APEX-2
 APEX-2
 APEX-3
 APEX-3
 APEX-3
 APEX-3
 

Figure 13-11. Effects of background correction on emission indices of individual organic groups 

for: (a) n-Alkanes; and (b) PAHs. 
This page intentionally left blank. 

252
 

 

 

 

 

 

14. Quality Assurance 

14.1 Data Quality Indicator Goals 

The DQI (Data Quality Indicator) goals that were established prior to the three testing campaigns and 

referenced in the respective QAPPs are presented in Table 14-1. 

Table 14-1. DQI Goals for DEAL Instrumentation 

Experimental 

Parameter 

Measurement 

Method Precisiona

 Accuracyb Completeness Detection Limit or 

Range 

[APEX-1]:Gas phase 

measurements (CO2, 

CO, THC) 

Photoacoustic 

analyzer ± 5% ± 5% 95% 

CO2: 3.4 ppmv 

CO: 0.2 ppmv 

THC (as hexane): 

0.008 ppmv 

[APEX-2 and APEX-3]: 

Gas phase 

measurements (CO2)

 c Infrared analyzer ± 5% ± 5% 95% 

0 to 800 ppmc 

0 to 2000 ppm 

[APEX-3]: Gas phase 

measurements (CO2)

 d Infrared analyzer ± 5% ± 5% 95% 0- to 10,000 ppm 

K-type: -200°C1250°C 

Temperature Thermocouple 5% + 5% 95% J-type: 0 °C-750°C 

T-type: -250 °C – 350 

°C 

Volumetric air flow rate Mass flow 

controllerse 5% + 10% 95% 

0-2 Lpm; 0-15 Lpm; 

0-50 Lpm; 0-112 Lpm; 

0-1120 Lpm 

Differential pressure Transducers 5% + 10% 95% 0-17.5 inches H20 

PM massf Gravimetric 

analysis 3 μgg + 15 μg 90% 1 μg 

a Calculated as the RSD of the reference measurements obtained at a constant instrument set point. 

b Average variation between the reference measurements and instrument readings as determined over the entire
 


operating range. 
 

c

 0 to 800 ppm used for APEX-2; 0 to 800 ppm and 0 to 2000 ppm used in APEX-3. 
 

d Horiba Model AIA 210. 
 

e Includes all on-line and time-integrated instruments as well as sampling tunnels. 
 

f

 For time-integrated sampling only. 
 

g

 Determined as the standard deviation of the results of multiple analyses of the same filter on the same microbalance. 
 

253
 

 

All of the instruments used were calibrated before and after APEX-1 and before the APEX-2 field 

campaign. APEX-3 followed shortly thereafter. Although not all of the instrumentation was calibrated 

following APEX-3, all measurements were taken within the annual calibration window and, therefore, 

there should be no resulting impact on data quality. 

14.1.1 Photoacoustic Analysis (APEX-1) 

Table 14-2 lists the optical filters and the calibration gas concentrations used with the 

B & K Photoacoustic Multigas Analyzer during APEX-1. The analyzer was set up and calibrated for each 

of the three gas channels before departing for the test campaign. 

Table 14-2. INNOVA 1314 Photoacoustic Multigas Analyzer Calibrations 

Optical 

Filter 

Gas Name Span Gas 

Concentration 

UA0983 Carbon Dioxide (CO2) 924 ppm 

UA0984 Carbon Monoxide (CO) 41.8 ppm 

UA0987 Total Hydrocarbons (THC) as n-Hexane 5.37 ppm 

Water Water (H20) N/A 

Quality control checks for the three gas compounds (CO2, CO and n-hexane) measured by the 

photoacoustic analyzer were performed before each test during APEX-1 per the QAPP. Post-test 

calibration checks were not possible due to physical and time constraints that restricted access to the test 

site. Therefore, span and zero calibration checks for the photoacoustic analyzer were performed once 

each day. Summaries of all the daily calibration checks are included in the paragraphs below and are 

summarized in Table 14-3. 

Table 14-3. DQI Values for Photoacoustic Analyzer Gas Measurements for All Tests 

Gas 

Compound 

Calibration Check 

Range 

(ppm) 

Accuracy 

(% bias) 

Precision 

(% RSD) Percent Complete 

CO2 891– 960 3.6 – 3.9 <2 100 

CO 39.8 – 41.3 1.2 – 4.8 <2 100 

THC 4.95 – 5.58 3.9 – 7.8 <2 88 

Calibration checks for CO2 ranged from 891 ppm to 960 ppm. This range represents an accuracy range of 

3.6 to 3.9 percent, which meets the 5 percent DQI goal. Precision for all CO2 measurements was <2 

percent, which also meets the 5 percent DQI goal. CO2 measurements during APEX-1 were 100 percent 

complete. 

Measured calibration checks for CO ranged from 39.8 ppm to 41.3 ppm. This range represents an 

accuracy range of 1.2 to 4.8 percent, which meets the 5 percent DQI goal. Precision for all CO 

measurements was <2 percent, which also meets the 5 percent DQI goal. CO measurements for APEX-1 

were 100 percent complete. 

254
 
 

 

THC calibration checks ranged from 4.95 ppm to 5.58 ppm. This range represents an accuracy range 

from 3.9 to 7.8 percent, which falls slightly above the 5 percent DQI goal. Precision for all THC 

measurements was <2 percent, which meets the 5 percent DQI goal. Of the 26 measurements made, 

three were below 5.1 ppm, a value which represents the lowest acceptable value. This number of 

measurements results in a completeness of 88 percent, which falls below the 95 percent completeness 

goal. 

14.1.2 Infrared CO2 Gas Analyzers (APEX-2 and APEX-3) 

Two identical Milton Roy 3300A infrared gas analyzers were used to measure the CO2 gas concentration 

during APEX-2 and APEX-3. One analyzer was installed to measure a sample from the plume tunnel and 

the second to measure a sample from the background tunnel per the equipment configuration diagrams 

included in the QAPP. The analyzers were equipped with three selectable ranges of 0-800, 0-1600, and 

0-2000 ppm. Calibrations for both analyzers were performed on August 2, 2005, before departing for the 

APEX-2 field campaign. Calibrations were performed on October 10, 2005, for the 0 to 2000 ppm range 

before departing for APEX-3. 

One Horiba Model AIA 210 infrared gas analyzer was used in APEX-3 only and was calibrated in the 

DEAL on October 17, 2005, prior to departing for the field campaign. 

These calibrations, summarized in Table 14-4, generated a linear relationship between the voltage output 

of the analyzers and the calibration gases. 

Daily calibration checks performed during the APEX-2 and APEX-3 campaigns are summarized in the 

following paragraphs and in Table 14.5. 

Table 14-4. Carbon Dioxide Analyzer Calibrations 

Gas Analyzer Gas Name Span / Mid Gas 

Concentrations 

Milton Roy 3300A – Plume (APEX-2 only) CO2 710 ppm / 454 ppm 

Milton Roy 3300A – Background (APEX-2 and APEX-3) CO2 710 ppm / 454 ppm 

Milton Roy 3300A – Plume Low Range Analyzer (APEX-3 only) CO2 1730 ppm / 1103 ppm 

Horiba AIA 210 – Plume High Range Analyzer (APEX-3 only) CO2 5610 ppm / 8570 ppm 

255
 

 

 

Table 14.5 DQI Values for Infrared CO2 Gas Analyzer Measurements for All Tests 

Gas 

Compound 

Plume Background 

Accuracy 

(% bias) 

Precision 

(% RSD) 

Percent 

Complete Daily Calibration 

Check Range 

(ppm) 

CO2 Span Gas 

(APEX-2) 

709.5 – 734 705 – 716 −0.7 to 3.4 <3 

100* 

CO2 Mid-range 

(APEX-2) 

439 – 467 429 – 461 −3.3 to 2.9 (P) 

−5.5 to 2.9 (B)* <3 

CO2 Span Gas, 

High Range 

(APEX-3) 

8319 – 8807 --­ −3 to 3 0 – 1 

100 

CO2 Span Gas, 

High mid-range 

(APEX-3) 

5613 – 5905 --­ 0 to 5 1 –3 

CO2 Span Gas, 

Low Range 

(APEX-3) 

1719 – 1786 --­ −1 to 3 0 – <1 

90 

CO2 Span Gas, 

Low mid-range 

(APEX-3) 

1104 --­ 0 to 6 0 – <1 

CO2 Span Gas 

(APEX-3) --­ 699 – 736 −2 to 4 0 – 1 

100 

CO2 Mid-range 

(APEX-3) --­ 438 – 474 −4 to 4 0 – 2 

* With the exception of one low reading of 429 ppm in the analyzer used to sample background. 

Daily calibration checks for the CO2 span gas concentration during the APEX-2 campaign ranged from 

709.5 to 734 ppm for the analyzer used to sample the plume, and from 705 to 716 ppm for the analyzer 

used to sample the background. This range represents an accuracy range for both analyzers of −0.7 to 

3.4 percent to meet the DQI goal of ± 5 percent. 

Daily calibration checks for the CO2 mid-gas concentration during APEX-2 ranged from 439 to 467 ppm 

for the analyzer used to sample the plume. This range represents an accuracy range of −3.3 to 2.9 

percent for the plume analyzer to meet the DQI goal of 5 percent. The analyzer used to sample 

background ranged from 429 to 461 ppm, a range which represents an accuracy range of −5.5 to 2.9 

percent. This range failed to meet the DQI goal of ± 5 percent for one reading of 429 ppm. This value is 

the only reading that failed to meet the accuracy DQI goal and there is no explanation for the low value. 

The same instrument performed exceptionally well the day before and the day after for the mid-calibration 

checks, with readings of 460.7 and 450.1 ppm, respectively. These values represent accuracy values of 

1.5 and −0.7 percent, respectively. Precision for all CO2 measurements taken with both analyzers was 

less than 3 percent to meet the DQI goal of 5 percent. With the exception of the one low reading, CO2 

measurements were 100 percent complete. 

256
 
 

During the APEX-3 campaign, three gas analyzers were used to measure CO2 concentrations. Two 

analyzers were used to sample from the “plume tunnel” with ranges of 0 to 2000 ppm and 0 to 10,000 

ppm. One analyzer was used to sample from the “background tunnel” at a range from 0 to 800 ppm. 

The span gas calibration checks for the Plume High Range CO2 Anlayzer ranged from 8319 ppm to 8807 

ppm, with an average of 8559 ppm. These values represent an accuracy range of −3 to 3 percent and a 

precision ranging from 0 to 1 percent. The mid-range gas calibration checks for the same analyzer ranged 

from 5613 ppm to 5905 ppm, with an average overall reading of 5742 ppm. The accuracy values ranged 

from 0 to 5 percent and the precision ranged from 1 to 3 percent. Plume High Range CO2 measurements 

were 100 percent complete. 

The span gas calibration checks for the Plume Low Range CO2 Analyzer ranged from 1719 ppm to 1786 

ppm, with an average of 1742 ppm. These values represent an accuracy range of −1 to 3 percent, and a 

precision range from 0 to <1 percent. The mid-range gas calibration checks for the same analyzer ranged 

from 1104 ppm to 1159 ppm, with an average overall reading of 1133 ppm. The accuracy values ranged 

from 0 to 6 percent (highest value slightly exceeded the DQI goal of 5 percent) and the precision ranged 

from 0 to <1 percent. Plume Low Range CO2 measurements were 90 percent complete, a level which fell 

slightly below the 95 percent goal. 

The span gas calibration checks for the Background CO2 Analyzer ranged from 699 ppm to 736 ppm, with 

an average of 713 ppm. These values represent an accuracy range of −2 to 4 percent and a precision 

ranging from 0 to 1 percent. The mid-range gas calibration checks for the same analyzer ranged from 438 

ppm to 474 ppm, with an average overall reading of 450 ppm. The accuracy values ranged from −4 to 4 

percent and the precision ranged from 0 to 2 percent. These measurements were 100 percent complete. 

14.1.3 DQI Measurements for Volumetric Air Flow Rates 

For APEX-1, APEX-2 and APEX-3, calibrations for the filter sampler mass flow meters and mass flow 

controllers were completed annually by the EPA Metrology Laboratory. The calibration files will be 

archived as part of the permanent record of the study. The DQIs can be assessed using the Metrology 

Laboratory reports and the information they provide. The reports include a "combined expanded 

uncertainty" value that is applicable over the calibration range of the particular device. All volumetric flows 

were recorded on the DAS and were monitored closely before, during, and after testing. No unexpected 

behavior was observed during the field campaigns, and it is therefore assumed that the true value is ± the 

uncertainty of the recorded value. These measurements were 100 percent complete. 

During the APEX-1 campaign, the major and minor sampling tunnel flows were measured using thermal 

dispersion mass flow transmitters that provided feedback to a pair of variable speed blowers. The ability 

of this system to precisely control the flow rate was impractical to test prior to the system being subjected 

to the ram effects from the jet engine exhaust. The blowers functioned properly in providing a sample flow 

into the DEAL that was sufficient for the particle measurement instruments to draw a slipstream via their 

own internal or external pump. Since isokinetic sampling was not a requirement and a sufficient sample 

was delivered, the quality of the data does not appear to have been compromised as a result of these 

imprecise measurements. The only compromise that could be a result of these imprecise measurements 

would be having an unknown cutpoint for the virtual pre-separator. However, the main function of the 

virtual impactor was to remove the larger particles that were not of interest and that could result in the 

need for more frequent instrument cleaning. The EPA Metrology Laboratory performed calibrations of 

these devices. The calibration files will also be archived. 

257
 
For the APEX-2 and APEX-3 campaigns, new centrifugal blowers, each controlled by variable frequency 

drives, were installed in the DEAL to replace the sample extraction system used in APEX-1. The new 

blowers substantially improved flow stability in the plume sampling tunnel. 

14.1.4 Temperature (Thermocouples) 

The DEAL thermocouples are calibrated annually by the EPA Metrology Laboratory. The calibration files 

will be archived as part of the permanent record of the study. The thermocouple DQIs can be assessed 

using the Metrology Laboratory reports and the information they provide. The reports include a "combined 

expanded uncertainty" value that is applicable over the calibration range of that thermocouple. As long as 

there were no observations of a thermocouple responding with unexpected values, it can be assumed 

that the true value is ± the uncertainty of the recorded value. Metrology Laboratory experience has 

determined that thermocouple results are consistent and reliable within one year of the calibration date. 

No measurements were made during the field campaigns that fell outside of the calibration range of the 

thermocouples; therefore, these measurements were 100 percent complete. 

14.1.5 DQI Measurements for Differential Pressure 

The Validyne PD55 and the Modus R12 differential pressure transducers were calibrated by the EPA 

Metrology Laboratory so that the field campaigns took place within a year of the calibration date. The 

Validyne PD55 was used in APEX-1 and the Modus R12 was used in APEX-2 and APEX-3. The 

calibration files will be archived. The differential pressure transducer DQIs can be assessed using the 

Metrology Laboratory report and the information this report provides. The report includes a "combined 

expanded uncertainty" value that is applicable over the calibration range of the pressure transducer. As 

long as there were no observations of the transducer responding with unexpected values, it can be 

assumed that the true value is ± the uncertainty of the recorded value. No measurements were made 

during the field campaigns that fell outside of the calibration range of the differential pressure transducers; 

therefore, these measurements were 100 percent complete. 

14.2 Post-Test Laboratory Analysis 

14.2.1 Gravimetric Analysis of Teflon Filter Samples 

As described by MOP-2503 for filter gravimetric analysis (see Table 4-7), sample weighing was 

conducted at specified ranges of room temperature and relative humidity. The balance stability was 

controlled by checking the variations of the standard weights before and after analysis. A control Teflon 

filter was used to monitor the long-term balance stability. 

Table 14-6 shows the results of a QC check of the variations in these parameters during the gravimetric 

analysis that was conducted for the APEX-3 samples. The balance exhibited good stability with RSDs of 

less than 0.002 percent. The RSD was 0.8 percent for weighing room temperature and 1.2 percent for 

weighing room relative humidity, indicating that the gravimetric analysis was done under the required 

strictly controlled environmental conditions. Table 14-6 also includes replicate weights obtained for 100 

mg and 200 mg standards used to assess accuracy/bias. All of the weights obtained met the DQI 

accuracy goal of ± 0.015 mg. 

258
 
 

 

 

 

 

 

 

 

 

 

 

 

Table 14-7 documents the standard deviation of replicate tare weights observed for individual APEX-3 

Teflon filters. These standard deviations were equal to 0.003 mg or less, a value which also met the QA 

precision requirement. 

The replicate final weights of APEX-3 Teflon filter samples are shown in Table 14-8. The values in the 

table were measured on three different days: 1/16, 1/18 and 1/20/06. The standard deviation in replicate 

sample weight measurement was less than 0.05 mg. By comparing the weights measured on 1/16 and 

1/20, consistent losses were observed for almost all the samples as shown in Figure 14-1. This weight 

reduction is considered to be primarily attributable to slight sample losses by vaporization of volatile 

materials during the sample measurement procedure (in particular, during the 24-hour equilibrium prior to 

weighing). The detection limit of this sampling technique was limited due to the low mass of PM collected 

on the filters. Therefore, the usability of these data is limited. 

Table 14.6 	 Variations in Environmental Conditions and Balance Stability for APEX-3 Teflon 

Filter Gravimetric Analysis 

Date Time 

Temp RH 

Control 

TF 

Blank 

TF Standard Weight 

(F) (%) (mg) (mg) (100 mg) (200 mg) 

10/17/05 69.5 36.0 172.627 174.773 99.994 199.993 

172.627 199.993 

172.627 199.993 

172.627 199.992

 14:57 70.0 36.3 172.629 174.772 99.995 199.990

 17:15 70.0 36.3 

10/18/05 14:50 69.9 36.0 

16:48 70.5 36.5 

10/19/05 71.0 37.0 

71.0 37.0 

10/21/05 70.0 37.0 172.633 174.780 99.993 199.993 

172.634 174.769 99.996 199.993 

172.632 174.774 

Standard Deviation 0.54 0.44 0.003 0.004 0.001 0.001 

Relative SD (%) 0.77 1.19 0.002 0.002 0.001 0.001 

259
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 14-7. Standard Deviation of Replicate Tare Weight Measurement for Each of APEX-3 Teflon 

Filters 

Filter ID Tare Weight (mg) Standard 

Deviation 

1 2 3 4 5 6 7 8 mg 

T101305A 152.394 152.393 0.001 

T101305B 150.436 150.437 0.001 

T101305C 151.785 151.786 0.001 

T101305D 148.281 148.284 148.280 148.280 0.002 

T101305E 147.762 147.761 0.001 

T101305F 148.521 148.523 148.519 148.524 148.523 148.522 0.002 

T101305G 149.070 149.071 0.001 

T101305H 149.312 149.309 149.311 149.312 0.001 

T101305I 149.999 149.998 0.001 

T101305J 151.229 151.226 151.228 151.229 0.001 

T101305K 151.106 151.101 151.099 151.103 151.103 151.103 0.002 

T101305L 144.638 144.637 0.001 

T101305M 148.034 148.034 0.000 

T101305N 146.045 146.043 146.047 146.044 146.046 146.041 146.039 146.041 0.003 

T101305O 146.488 146.487 0.001 

T101305P 147.761 147.761 0.000 

T101305Q 149.349 149.349 0.000 

T101305R 147.470 147.470 0.000 

T101305S 146.170 146.169 0.001 

T101305T 146.722 146.718 146.720 146.715 146.718 146.717 0.002 

T101305U 147.734 147.730 147.734 147.733 0.002 

T101305V 147.462 147.464 147.462 147.465 147.465 147.465 0.001 

T101305W 149.207 149.209 149.206 149.210 149.208 149.208 0.001 

T101305X 145.766 145.767 0.001 

T101305Y 147.371 147.374 147.370 147.375 147.377 147.371 147.376 0.003 

260
 

 

 

 

 

 

 

 

 

 

Table 14-8. Replicate Final Weight Measurement for Each APEX-3 Teflon Filter 

Filter ID 

1/16/06 

(mg) 

1/16/06 

 (mg) 

1/18/06 

 (mg) 

1/18/06 

(mg) 

1/20/06 

 (mg) 

1/20/06 

 (mg) 

SD 

(mg) 

T101305A 152.547 152.542 152.531 0.008 

T101305B 150.489 150.468 150.467 0.012 

T101305C 151.838 151.804 151.798 0.022 

T101305D 148.352 148.318 148.265 0.044 

T101305E 148.345 148.332 148.325 148.324 148.323 148.320 0.009 

T101305F 148.635 148.587 148.584 0.029 

T101305G 149.444 149.435 149.437 149.432 0.005 

T101305H 149.324 149.315 0.006 

T101305I 150.067 150.060 0.005 

T101305J 151.276 151.247 151.239 151.241 0.017 

T101305K 151.258 151.250 151.247 0.006 

T101305L 144.696 144.659 144.656 0.022 

T101305N 146.070 146.064 0.004 

T101305O 146.749 146.743 0.004 

T101305P 147.794 147.772 0.016 

T101305Q 149.374 149.351 149.351 0.013 

T101305S 146.204 146.187 146.181 0.012 

261
 


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Teflon Filter Fin al We ight ( mg) 

T101305A
 

T101305B
 T101305C T101305D 

T101305E 

T101305F

T101305G

T101305H
 

T101305I

T101305J

T101305K
 

T101305L

T101305N
 

153 

152 

151 

150 

149 

148 

147 

146 

145 

144 
 
 

1/16/06 

1/20/06 

T101305O

T101305P 

T101305Q

T101305S
 

Figure 14-1. Sample losses from the comparison of weights measured on 1/16/06 and 1/20/06. 

14.2.2 PM Organic Speciation Analysis 

14.2.2.1 Solvent Extraction - GC/MS 

The speciation of APEX-2 quartz filter samples was conducted by solvent extraction and GC/MS analysis. 

Five-level standard calibration curves were prepared and injected onto the GC/MS system prior to 

analysis of all quartz filter samples. These calibration curves consisted of aromatic PAHs (NIST1491 and 

NIST 2260 standards), the second calibration curve of semivolatile alkanes (NIST 1494), and the third 

calibration curve of methyl esters of organic acids [Quantitative Standard #3 (QS#3) from University of 

Wisconsin]. The standard deviations for all calibration components were below 30 percent (most below 

15%) for nearly all target compounds. 

A method detection limit (MDL) study was also conducted prior to sample analysis. The lowest calibration 

level (the practical quantitation limit, or PQL) was chosen to be the level that was replicated seven times 

in accordance with EPA’s SW-846 guidelines (Test Methods for Evaluating Solid Waste, 

Physical/Chemical Methods) for determination of an MDL. The standard deviation was multiplied by 3.14 

(chart values for seven replicates) to determine each MDL. Sample values that fell below the MDL were 

not used. 

Some compounds were not present in the standard and were quantified using relative response factors 

from closely eluting similar compounds. The qualitative determination of these non-target components 

262
 

 

 

was facilitated using retention times gathered from an extracted wax resin and also by using 

fragmentation library matching. 

Due to the punches taken from the quartz filter samples for OC/EC analysis before solvent extraction, a 

compensation was required to account for sample losses. Since the exposed area of each quartz filter 

was 13.45 cm2 and each punch had a known area of 1.45 cm2

, the total nanogram (ng) value of the filter 

was multiplied by a factor of 1.12 if one punch was taken from the filter. 

Overall target analyte validity was determined by the presence of the target ion plus the molecular ion 

(alkanes)/qualifier ions. Comparison of isotopic ratios and retention times with daily standards as well as 

known mass spectral libraries assisted greatly in this process. Since the GC/MS system used was 

equipped with an electronically programmable control (EPC), retention times did not shift appreciably 

throughout the analysis period. This stability of retention times was critical for accurate determination of 

target analyte components, especially when good isotopic ratio comparisons/lack of molecular ion 

(alkanes) were not a viable option. In certain cases, the levels of interfering ions were judged to be 

significant, and these particular components were deemed invalid. These results were not used. 

Spikes were performed to determine the recoveries of individual components. Excellent recoveries were 

found for most of the targets as shown in Table 14-9. 

14.2.2.2 Thermal Desorption – GC/MS 

The quartz filter samples collected during APEX-1 and APEX-3 were analyzed using the thermal 

desorption (TD) system with GC/MS. Quantitative analysis was performed for semivolatile alkanes and 

PAHs. 

Due to the known low organic content in the quartz filter samples, a single level (high level 1) calibration 

was used to quantify the data set. A lower calibration level (mid level 2) was used as the closing standard 

and laboratory acceptance criterion. The standard had 83 percent of the components fall within 20 

percent of the actual values. More than 75 percent of the target components meet the acceptance criteria, 

meaning the calibration was valid. A valid calibration ensured that all of the samples and blanks analyzed 

were bracketed by a successful stable calibration. 

Blanks were analyzed prior to the analysis of each sample to determine cleanliness of the TD/GC/MS 

system. Cleanliness of the TD/GC/MS system was of particular importance due to the nature of the TD 

methodology and the relative inefficiency of system cleansing for the components with higher boiling 

points in complex matrices. A method was specifically designed to purge the system of all residual target 

components. This purging method allowed the TDS split vent to open and purge the system at 90 ml/min 

for 10 minutes under high heat. This procedure was conducted prior to each sample run. An additional 

intensive rinsing procedure was developed to minimize target contamination. 

Maximum sample load was determined by a pre-study. The pre-study demonstrated that a maximum of 

three quantitative slivers (2 mm × 30 mm) could be contained within the critical 79 mm “optimal heat 

zone.” Loading more sample slivers would have proved more difficult and could have potentially resulted 

in adverse affects such as poor thermal transfer and internal standard biasing. The methodology proved 

to have enough organic material present for each sample to acquire meaningful data without jeopardizing 

thermal transfer to the GC/MS. 

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Table 14-9. Recoveries of Individual Components by Solvent Extraction Analysis 

Compound

Napthalene 

 % Recovery 

 78% 

Compound

Squalene 

 % Recovery 

110%

1-Methylnaphthalene 91% n-Heptacosane 130% 

2-Methylnaphthalene 91% Pristane 86%

2,6-Dmethylnaphthalene 94% n-Octacosane 131% 

Acenapthylene 93% n-Nonacosane 128% 

Acenapthene 95% n-Triacontane 128% 

Dibenzofuran 92% n-Hentricontane 123% 

Fluorene 103% n-Dotriacontane 116% 

Methylfluorene 96% n-Tritriacontane 116% 

Phenanthrene 101% n-Tetratriacontane 113% 

Anthracene 114% n-Pentatriacontane 120% 

9-Methylanthracene 99% n-Hexatriacontane 112% 

Fluoranthene 110% n-Heptatriacontane 107% 

Retene 113% n-Octatriacontane 106% 

n-Decane 26% Pyrene 93%

n-Undecane 66% Benzo(ghi)fluoranthene 114% 

n-Dodecane 86% Cyclopenta(cd)pyrene 95% 

n-Tridecane 96% Benz(a)anthracene 101% 

n-Tetradecane 99% Chrysene 98%

n-Pentadecane 102% 1-Methylchrysene 108% 

n-Hexadecane 104% Benzo(b)fluoranthene 101% 

n-Heptadecane 105% Benzo(k)fluoranthene 100% 

n-Octadecane 106% Benzo(e)pyrene 108% 

Phytane 110% Benzo(a)pyrene 115% 

Dodecylcyclohexane 111% Perylene 122%

n-Nonadecane 113% Indeno(1,2,3-cd)pyrene 99% 

2-Methylnonadecane 126% Dibenzo(a,h)anthracene 99% 

3-Methylnonadecane 127% Benzo(ghi)perylene 113% 

n-Eicosane 102% Coronene 87%

n-Heneicosane 108% ABB-20R-C27-Cholestane 74% 

Pentadecylcyclohexane 114% AAA-20S-C27-Cholestane 

ABB-20R-C28­

91% 

Docosane 111% Methylcholestane 

ABB-20R-C29­

98% 

Tricosane 118% Ethylcholestane 95% 

17A(H)-22,29,30­

Tetracosane 122% Trisnorhopane

17B(H)-21A(H)-30­

 82% 

Pentacosane 120% Norhopane 115% 

Hexacosane 125% 17A(H)-21B(H)-Hopane 96% 

Nonadecylcyclohexane 98% 

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14.2.2.3 IC Analyses 

The quality of the inorganic water-soluble ion analysis was evaluated by comparing the results of three 

replicate injections of the sample extracts. Table 14-10 provides the RSD for some of the filter samples 

analyzed, all of which met the measurement acceptance criterion of ± 15 percent established for the IC 

analyses. 

14.2.2.4 XRF Analyses 

In the XRF analytical report, the concentrations of elements were reported together with their 

uncertainties. To insure the quality of the emissions data calculated accordingly, a criterion was set to 

discriminate the data reported. Only an element with a concentration three times greater than its 

uncertainty was considered acceptable for further emission factor estimation. 

Table 14-10. Relative Standard Deviation in IC Measurements 

Sample ID 

NH4 Cl SO4 NO3 

% % % % 

T032204O 0.990 3.95 

T032304U 3.08 0.747 

T032403A 2.64 

T032204Q 1.13 3.44 

T080105B 0.845 1.25 

T080105F 1.77 2.97 0.941 

T080105G 2.98 

T080105E 3.57 7.75 

T108105I 7.72 2.25 

T101305E 5.30 0.784 

T101305F 1.10 

T101305D 5.68 2.82 

T101305G 14.0 0.669 

T101305K 3.27 0.340 

T101305J 1.92 

T101305N 1.30 1.10 

T101305O 2.04 

14.2.2.5 EC/OC Analyses 

Single point calibrations were performed daily prior to analysis of samples using a known amount of 

sucrose solution spiked into a filter cut. If the results of this calibration check were within ± 5 percent of 

the known value, the sample analysis was performed. If results of the calibration were outside the ± 5 

percent criterion, the instrument was recalibrated and analysis of the spike was repeated until an 

acceptable value was achieved. Instrument blanks were also performed with each batch of samples and 

at least one sample was analyzed in duplicate. All accuracy and precision objectives were met and the 

analyses were 100 percent complete. 

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15. Conclusions and Recommendations 

A number of conclusions were reached as a result of the APEX testing program. These conclusions are 

as follows: 

•	 The testing of aircraft turbine engine emissions is difficult, requiring long sampling lines with their 

associated high residence time and particle losses. Corrections were made for particle losses, but the 

impact of the long residence time has yet to be established. 

•	 The PM mass emission index ranged from approximately 10 to 550 mg/kg of fuel burned, depending 

on engine and fuel type, operating power, and environmental conditions. 

•	 For the turbofan engines tested, the relationship of ElM to fuel flow (engine power) followed a 

characteristic U-shape with the emissions high at idle, dropping off to a minimum at mid-range power, 

and rising again at high engine thrust. 

•	 The particle number emission indices observed in the program ranged from approximately 1(10)15 to 

1(10)17 particles/kg of fuel burned, again depending on engine and fuel type, operating power, and 

environmental conditions. 

•	 For most of the turbofan engines tested, a logarithmic relationship of EIN to fuel flow (engine power) 

was determined in the general form: 

EI = m(ln fuel flow) + b	 (15-1) 

where 

m = slope of the regression line = -2(10)15 to -3(10)16 

b = intercept of the regression line = 2(10)16 to 2(10)17 

• Both ElM and EIN were found to increase with increasing fuel sulfur content. For ElM, the PM emission 

increased linearly with fuel sulfur, whereas for EIN, the increase appears to be more of an exponential 

function. 

•	 Engine operating temperature had a measurable effect on both ElM and EIN. In both cases, the 

emissions were slightly lower (i.e., ~8%) when the engine was warm. 

•	 The particle size distributions of the emissions found in the study were generally unimodal and 

lognormally distributed with electrical mobility diameters ranging from ~3 to slightly larger than 

100 nm. At higher power levels, a small accumulation mode was also observed. 

•	 Both the GMD and GSD of the PSD also varied with engine and fuel type, thrust, and environmental 

conditions. The GMD ranged from approximately 10 to 30 nm (electrical mobility diameter) and the 

GSD ranged from 1.4 to 2. 

267
 
 

•	 In general, the largest GMDs and GSDs were obtained at high power conditions. The observations 

suggest that the PSDs produced by the engines tested under power conditions of <30% rated thrust 

were unimodal and consisted of primary nuclei particles, whereas for thrust levels >85%, 

accumulation mode particles were formed, and the PSD curves became broader. 

•	 A comparison of measurement techniques for PM mass, number, and size indicated significant 

discrepancies between instruments. Of particular note is a comparison of the ElM obtained by the 

Nano-SMPS and the time-integrated Teflon filter sampling. The filter-based method always produced 

higher values than the SMPS-based method and there was no linear correlation between the two 

techniques. 

•	 Of the various instruments used to measure PM mass, number, and size, the SMPS appears to be 

the most reliable. The lack of correlation with the filter-based technique is disturbing, however, and an 

area worthy of further investigation. 

•	 The emission indices for BC and particle surface-bound PAHs generally follow trends similar to ElM 

discussed above, except that: (1) BC was always highest at high power, and (2) fuel composition had 

no measureable effect on either BC or PAH emissions. However, the BC and PAH on-line 

measurements were highly variable and oftentimes did not track well with power changes. 

•	 The chemical composition of the gas-phase NMVOCs and carbonyls varied by engine type as 

measured on a time-integrated basis over all power conditions. However, significant quantities of a 

number of compounds listed in the Clean Air Act as HAPs were found in some or all engines 

including formaldehyde, acetaldehyde, benzene, acrolein, toluene, and 1,3-butadiene. 

•	 The elemental composition of the PM samples collected on Teflon filters was dominated by sulfur. In 

some samples, however, significant amounts of crustal elements such as silicon were also found due 

to the resuspension of concrete cuttings generated during installation of the sampling probes and 

lines. 

•	 Sulfate was by far the most abundant water-soluble ion determined from the Teflon filter samples. 

Calculations of the transformation of S(IV) in the fuel to S(VI) indicate conversion rates in the range of 

2 to 4%, a conversion rate which compares favorably to the rates obtained by other investigators. 

•	 The emission indices determined in the program for OC and EC as determined from quartz filter 

sampling ranged from 37 to 83 mg/kg fuel for OC and 21 to 98 mg/kg fuel for EC, respectively. The 

ratio of EC to OC ranged from 0 to almost 2 depending on the engine type and fuel being tested. 

•	 Over 70% of the particle-phase organic compounds, also determined from the quartz filters, consisted 

of n-alkanes and PAHs. Also, of the engines tested, the CFM56-3B1 and AE3007A1E had the highest 

emission indices of total speciated organic compounds, whereas the P&W 4158 and CFM56-7B24 

had the lowest. 

•	 The results obtained in the study are at least generally comparable to those of other APEX 

investigators. However, a report of the APEX-3 results from the other groups has not as yet been 

released. 

Based on the above conclusions, the following recommendations for future research are offered for 

consideration by funding agencies: 

268
 
•	 One major issue to be resolved in future work is the effect of the sampling system on the 

experimental results. This effect includes both particle losses in the sampling lines as well as the 

potential transformation of the aerosol from the point of collection to the point of measurement. A 

standardized sampling system with well-characterized performance should be employed in all future 

testing. Also, the issue of representative plume sampling should be addressed. 

•	 The lack of good agreement between instruments is also a significant issue warranting additional 

research. Of particular importance is the lack of correlation between on-line SMPS and filter-based 

methods for determining ElM. 

•	 Although particle losses through the sampling system can be characterized using traditional aerosol 

science techniques (e.g., NaCI aerosol), a reliable soot calibration source is needed that is both 

reproducible and stable. Although work is underway under both NASA and EPA Office of 

Transportation and Air Quality sponsorship to develop the necessary calibration equipment, additional 

research and development is definitely needed in this regard. 

•	 A reliable on-line method for the direct determination of PM mass emissions is needed. Neither the 

TEOM nor the QCM appears capable of conducting these measurements in a reliable manner. The 

TEOM is generally not sensitive enough and the QCM produces values higher than other methods 

and QCM sampling times are limited due to crystal saturation. 

•	 The effect of fuel composition is also an area worthy of additional investigation. In particular, the 

further examination of the influence of sulfur and aromatics on sulfate and organic emissions is 

needed to assess the impact of future aviation fuels on local air quality and global climate change. 

•	 Further work is needed in the characterization of plume aging. To date, all measurements have been 

performed in the near-field plume < 50 m from the engine exit. There are many issues related to 

fence-line and neighborhood air quality that need to be addressed at distances far greater than 50 m 

and multiple points downstream. For the plume aging tests, the instrumentation should be positioned 

directly in the plume to avoid problems with long sampling lines. 

•	 Additional chemical characterization of both the gas- and particle-phase emissions by power 

condition is needed. The data provided above are representative of all thrust levels during a particular 

test. However, specific data for at least the four ICAO-specified power conditions are needed in order 

to make a determination of the local air quality impacts from airports. 

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