U.S. Department of Energy

Office of Transportation Technologies

1000 Independence Avenue, S.W.

Washington, DC 20585-0121

FY 2000

Progress Report for Combustion and Emission 

Control for Advanced CIDI Engines

Energy Efficiency and Renewable Energy

Office of Transportation Technologies

Approved by Steven Chalk

November 2000
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

CONTENTS

 Page

iii

I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

II. EMISSION CONTROL SUBSYSTEM DEVELOPMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . .9

A. Emission Control Subsystem Evaluation for Light-Duty CIDI Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

B. Application of Advanced Emission Control Sub-Systems to State-of-the-Art Diesel Engines. . . . . . . . . . . . . . 15

III. IN-CYLINDER COMBUSTION STUDIES, ADVANCED COMBUSTION RESEARCH, 

SENSORS, AND DIAGNOSTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

A. Heavy-Duty Diesel Engine Combustion: Diffusion-Flame/Wall Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. Development of a Combined Mass Flow Rate and Chemical Composition Sensor for the Intake of CIDI Engines 

Using Thin Film MEMS Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

C. Advanced CIDI Engine Diesel Combustion R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

D. Extending Exhaust Gas Recirculation Limits in CIDI Engines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

E. Measuring the Cylinder-to-Cylinder Distribution of Recirculated Exhaust Gas during Transient Operation of a 

CIDI Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

F. Pressure Reactive Variable Compression Ratio Piston Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

G. HCCI Combustion Fundamentals: In-Cylinder Diagnostics and Kinetic-Rate Computations . . . . . . . . . . . . . . 50

H. Camless Variable Valve Timing System for a High-speed CIDI Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

I. Low-Friction Coatings for CIDI Fuel Injection System Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

J. Fuel Spray Measurement Using X-Rays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

IV. EXHAUST GAS NOX EMISSION CONTROL R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

A. Non-Thermal Plasma-Assisted Catalysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

B. Sulfur-Tolerant NOx Adsorber System Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

C. Reduction of NOx Emissions for Lean-Burn Engine Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

V. EXHAUST GAS PARTICULATE EMISSION CONTROL R&D . . . . . . . . . . . . . . . . . . . .87

A. Optical Diagnostic Development for Exhaust Particulate Matter Measurements . . . . . . . . . . . . . . . . . . . . . . . . 87

B. Diesel Particle Scatterometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

C. The Effect of Injector and In-Cylinder Conditions on Soot Formation in CIDI Engines . . . . . . . . . . . . . . . . . . 96

D. Microwave-Regenerated Exhaust Particulate Filter Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

1

I. INTRODUCTION

Developing Advanced Combustion and Emission Control Technologies

On behalf of the Department of Energy’s Office of Transportation Technologies 

(OTT), we are pleased to introduce the Fiscal Year (FY) 2000 Annual Progress 

Report for the Advanced Combustion and Emission Control Research and 

Development (R&D) Program. The Program is focused on the compression ignition, 

direct injection (CIDI) engine, an advanced version of the commonly known diesel 

engine, which is used in both light- and heavy-duty vehicles. Both the Office of 

Advanced Automotive Technologies (OAAT) and the 

Office of Heavy Vehicle Technologies (OHVT) conduct 

CIDI engine R&D and have coordinated their research 

plans to minimize overlap and maximize the use of 

available R&D funding. This year’s accomplishment 

report represents the output of this combined effort.

This introduction serves to briefly outline the nature, 

progress, and future directions of the Combustion and 

Emission Control for Advanced CIDI Engines R&D 

Program. Together with DOE National Laboratories and 

in partnership with private industry and universities across 

the United States, OTT engages in high risk research and 

development that provides enabling technology for fuel 

efficient and environmentally-friendly light- and heavyduty vehicles. The work conducted under this Program relies on the DOE Advanced 

Petroleum-Based Fuels Program to provide on-going reformulated diesel fuel 

developments, to enable meeting our out-year objectives. (The APBF Program is 

described in a separate report.)

The Combustion and Emission Control for Advanced CIDI Engines R&D 

Program supports the Partnership for a New Generation of Vehicles (PNGV), a government-industry 

partnership striving to develop, by 2004, a midsized passenger vehicle capable of achieving 80 

miles per gallon while adhering to future 

emissions standards and maintaining such 

attributes as affordability, performance, safety, 

and comfort. In 1997, following a rigorous 

process of technology down-selection, PNGV 

targeted CIDI engines as one of the promising 

technologies for achieving the 80 miles per 

gallon fuel economy in a light-weight hybrid 

vehicle. As scheduled in 2000, Ford, General 

Motors, and Daimler-Chrysler all delivered 

PNGV concept cars. All three of these concept 

cars used CIDI engines. Today’s CIDI engines 

achieve impressive thermal efficiency; 

however, in order to meet future emissions 

standards, advancements in clean combustion, 

emission control technology and diesel fuels 

Kathi Epping, 

Program Manager

Gurpreet Singh, 

Program Manager

Kenneth Howden, 

Program Manager

PNGV Concept Cars
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

2

are necessary. Similar to PNGV, the DOE/OHVT Light 

Truck goal is to increase the fuel efficiency of light trucks 

by 35 percent by 2004, while meeting emission standards 

that apply to both cars and light trucks. Because the 

emission challenges facing CIDI engines are very similar 

for both light- and heavy-duty vehicle applications, OAAT 

and OHVT have co-funded many of the projects whose 

reports are contained herein.

The Advanced Combustion and Emission Control R&D 

Program explores the fundamentals of combustion, how 

emissions are formed, and advanced methods for treating 

those emissions. Testing and modeling are also important 

elements of the program and enable us to evaluate potential 

technology and validate technology selection and direction. 

By working at the forefront of these new technologies, we 

hope to enhance the knowledge base that can be used by 

automotive partners and suppliers (engine manufacturers, 

catalyst companies, etc.) to develop advanced automotive systems.

Our program, which is cost-shared between industry and government, is sharply focused on improving 

combustion processes and emission control technologies. Progress in these areas will help overcome the 

critical technical barriers associated with the emission challenges of highly efficient CIDI engines, namely, 

higher than desired levels of nitrogen oxides (NOx) and particulate matter (PM) in the exhaust.

Technical Leadership

By providing strong technical 

direction and program and financial 

management, DOE has taken a leadership 

role in the development of technology to 

reduce exhaust emissions of highly 

efficient diesel engines while minimizing 

compromises in cost, performance and 

efficiency. DOE could not provide this 

leadership without the cooperative 

assistance of General Motors, 

DaimlerChrysler and Ford through 

participation in PNGV technical teams 

and the Low Emission Partnership (LEP). 

CIDI R&D in the OHVT is linked to 

PNGV through the DOE Diesel CrossCut Team, and receives cooperative 

assistance from DDC, Cummins, 

Caterpillar, and Navistar. The technology 

developed under our program will help 

the automakers overcome a critical barrier to producing light-duty passenger cars with up to three times the 

fuel economy of today’s conventional vehicles and light-duty trucks that are at least 35 percent more efficient 

while meeting strict emissions standards established by the Environmental Protection Agency (EPA) and the 

California Air Resources Board (CARB). 

The Development of High-Efficiency, Low-Emission 

CIDI Engines Requires Simultaneous Development 

of Clean Combustion, Emission Control Devices, and 

Advanced Fuels

Advanced Combustion and Emission Control Participants
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

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The unique scientific capabilities and facilities of the National Laboratories offer us the opportunity to 

target those technical areas of highest priority and those that require high-risk R&D that is seldom conducted 

independently by industry. We work with industry and through the PNGV technical teams to ensure that 

National Laboratory R&D activities fulfill industry’s needs for basic scientific understanding and development 

of new technologies, devices, materials, and processes. The R&D projects conducted are peer-reviewed each 

year by representatives from the auto manufacturers, heavy-duty engine manufacturers, emission control 

device manufacturers, and academic and other government agencies. This assures that the work being done is 

relevant to the ultimate users of the technologies.

Challenges

OTT programs have been successful in meeting 

many of the original milestones established by 

PNGV. The PNGV emissions goals established 

were 0.2 grams per mile for NOx and a "stretch" 

target of 0.01 grams per mile for PM. Subsequent 

to this, EPA finalized the Tier 2 emission 

regulations which lowered the average NOx emissions that would be allowed from light-duty vehicles. In a 

separate action, EPA has proposed to significantly lower the sulfur content of onroad diesel fuel. In light of 

these developments, the DOE R&D emission goals were re-evaluated to reduce emissions beyond the 

minimum required by EPA regulation. The DOE 2007 R&D emission goals target even lower emissions, 

while simultaneously improving engine efficiency and reducing emission control costs. Meeting the Tier 2 

standards requires NOx and PM emissions to be reduced by about 90 percent. In 2000, EPA has proposed to 

reduce the NOx and PM emissions of heavy-duty CIDI engines by 90 percent to 0.2 grams per bhp-hour for 

NOx and 0.01 grams per bhp-hour for PM. Achieving such low emissions cannot be done through engine 

development and fuel reformulation alone, and requires application of NOx and PM emission control devices. 

Meeting the DOE goals will facilitate the design of high fuel economy vehicles using CIDI engines to 

penetrate the market with resultant petroleum fuel reduction and emissions benefits.

Originally, it was believed that lean-NOx catalysts would have sufficient effectiveness to meet the NOx

goal, and oxidation catalysts would meet the PM goal. However, it has now become evident that the 

capabilities of lean-NOx and oxidation catalysts are too limited to reach the new goals. Currently, the most 

promising technologies to meet the NOx goals include adsorber catalysts and urea-based selective catalytic 

reduction (SCR), with non-thermal plasma systems showing much promise but needing much additional 

development. To meet the PM goals, it is likely that catalyzed and continuously regenerating particulate filters 

will be needed instead of just oxidation catalysts. While such devices look promising, several hurdles remain 

to be overcome, including durability, effective operation during transients and at low exhaust temperatures, 

recovery from exposure to high-sulfur fuels, minimization of the fuel economy penalty caused by use of 

reductants and electrical power for regeneration, increase in engine back pressure, and effective desulfurization 

schemes that will keep emission control devices operating near their peak effectiveness.

Accomplishments

In FY 2000, significant progress was made on emission control subsystems that would allow light- duty 

trucks to use CIDI engines and meet Tier 2 emission standards. We also saw improvements in catalyst 

technology to reduce NOx emissions, reduced power requirements for PM emission device regeneration, 

development of new sensors, improvements in the effectiveness of exhaust gas recirculation (EGR) to reduce 

NOx emissions, and more detailed characterization of combustion processes including advanced technologies 

such as homogeneous charge compression ignition.

DOE CIDI R&D Emission Goals, grams per mile

DOE 2004 R&D 

Goals

DOE 2007 R&D 

Goals

NOx 0.07 0.03

PM 0.01 0.01
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

4

Cummins Engine Company completed a vehicle/engine/emission 

control system performance model which was used to select an NOx

adsorber to be used as part of their subsystem development. Cummins is 

working with Englehard to specify and develop a suitable NOx adsorber 

for this application. The model Cummins developed predicts that the 

NOx adsorber will have to achieve an average effectiveness of 87 

percent or better to meet the 2004 R&D goal for NOx. Neither nonthermal plasma nor lean-NOx technologies showed sufficient 

effectiveness to be considered. Three Cummins ISB breadboard CIDI 

engines are being set-up and are being used for emission control system 

development and catalyst performance mapping. Work is proceeding on 

a hydrocarbon reductant system to regenerate the NOx catalyst. In future 

tasks, Cummins will design and develop a sulfur trap, and identify the 

optimum reductant that can be derived from diesel fuel.

Detroit Diesel Corporation has delivered a prototype CIDI engine 

sized for light trucks which will be used for development of the emission control system. Without emission 

controls, the engine has demonstrated FTP emissions of 1.5 grams per mile NOx and 0.8 grams per mile PM 

using conventional diesel fuel. The emission control system has been designed and aging tests have been 

initiated. With optimized combustion, EGR, and fuel injection systems to reduce engine-out emissions, the 

prototype engine is believed to be able to reach 0.6 grams per mile NOx. A model to predict pressure drop 

across PM filters was developed and testing has shown excellent correlation with experimental measurements. 

Pacific Northwest National Laboratory (PNNL) discovered new catalysts that reduce NOx over a wider 

temperature window when placed downstream of a plasma reactor, and have a predicted fuel economy penalty 

of 6 percent or less. Reduced emissions of formaldehyde and N2O (to negligible levels) were also observed. 

PM emission reductions of 92 to 96 percent were observed and demonstrated over a range of EGR conditions. 

NOx conversion efficiencies of over 70 percent at a temperature of 350o

C were achieved this year-a significant 

advancement over the 55 percent conversion efficiency achieved last year. These positive developments 

illustrate the potential of non-thermal plasma 

devices to reduce both NOx and PM emissions from 

CIDI engines. 

Industrial Ceramic Solutions continued their 

successful development of a microwave 

regenerated PM trap. They were able to increase 

PM removal to the range of 80 to 95 percent, which 

will enable CIDI vehicles to meet the most stringent 

Tier 2 PM standards (other than for zero-emission 

vehicles). Microwave regeneration of the filter 

cartridge, at engine idle operating conditions, 

demonstrated the ability to return the filter to within 

95%-100% of the "new" filter exhaust flow 

capacity. Calculations based on the data showed 

that a 1.9 liter Volkswagen engine, operating at 

cruising speed, would require regeneration 

approximately every six hours. The regeneration Microwave Regenerated PM Trap Particulate Emission 

Reduction Results from a 1.9 Liter Volkswagen Diesel Engine 

(FTP simulation using steady-state results)

Detroit Diesel Prototype DELTA CIDI 

Engine
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

5

will consume 1.75 kW of power over a period of two minutes. 

The microwave filter fuel penalty, as demonstrated in these 

tests, is 0.3 percent. 

Makel Engineering has designed a Micro-ElectroMechanical Systems (MEMS) sensor capable of measuring the 

temperature, pressure, flow velocity, and oxygen, hydrocarbon, 

and carbon dioxide contents of the intake air entering CIDI 

engines. The sensor is anticipated to be 1.5 cm in diameter and 

configured to be flush mounted in the intake system. The value 

of such sensors is their ability to take measurements quickly (on 

a cycle-by-cycle basis) providing instantaneously updated 

information for control of fuel injection (timing, quantity, rate, 

pilot and post injection) and EGR with the result of reduced 

engine-out emissions.

Ford Motor Company took the first steps to evaluating the 

potential of a pressure reactive piston which changes 

compression ratio in response to cylinder pressure. The benefits 

of the pressure reactive piston include cycle-by-cycle variation of compression ratio without the requirement 

of a complex control system. The expected benefits of the pressure reactive piston include lower engine-out 

NOx emissions, and lower engine friction and noise. Various spring types were investigated; however, the 

Belleville washer was chosen since it had the best configuration for this application, as well as the ability to 

carry high loads with small deflections. Engine simulation and experience were used to develop an initial 

spring pre-load and axial travel requirement. For the first application in a spark ignition configuration, the 

range in compression ratio was from 9.5:1 to 12:1. This variation in compression ratio demonstrated up to 17.3 

percent improvement in efficiency at low engine load (0.5 bar intake manifold pressure) with a minimum of 

3.6 percent improvement in efficiency at high engine load (1.0 bar intake manifold pressure). Testing in CIDI 

configuration will be initiated in the next fiscal year.

Oak Ridge National Laboratory has developed correlations between EGR and emissions from CIDI 

engines. These correlations facilitate development of control strategies to increase of the amount of EGR in 

CIDI engines which could result in significantly reduced NOx emissions. Sandia National Laboratory has 

developed an infrared, diode-laser based system to instantaneously measure EGR rate for each cylinder on a 

cycle-by-cycle basis. This detection system is useful to measure cylinder-to-cylinder variation in EGR under 

both steady-state and transient conditions. Optimum application of EGR will minimize engine-out NOx

emissions and cause a reduction in NOx emission control device size and cost.

Sandia National Laboratory made several advances in CIDI combustion diagnostics. By acquiring 

simultaneous OH-radical planar laser-induced fluorescence and PM planar laser-induced incandescence 

images, it was determined that PM is formed in diffusion flames and is then deposited on combustion surfaces. 

These PM emissions are subsequently removed from the combustion surfaces during the exhaust portion of the 

engine cycle. Sandia also identified the inability of traditional ignition models to accurately predict ignition 

delay and location under idle conditions in CIDI engines. 

Homogeneous charge, compression ignition (HCCI) has the potential to greatly reduce the NOx emissions 

from CIDI engines. Sandia has conducted a computational study of HCCI ignition timing across a wide range 

of engine design parameters and operating conditions including compression ratio, intake temperature and 

pressure, air/fuel ratio, engine speed, and EGR. Sandia used a chemical kinetic model to assist them, modified 

Ford Motor Company’s Pressure Reactive 

Piston
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

6

with full chemistry mechanisms for n-heptane and iso-octane that were obtained from Lawrence Livermore 

National Laboratory, which is using chemical kinetic modeling to predict formation of NOx and PM.

Future Directions

Our new program directions for FY 2001 build upon recent advances in technology development, and we 

will begin to move some of the more promising new technologies out of the laboratory and over to industry for 

testing and implementation. EPA’s proposed rule to lower the sulfur content of diesel fuel to less than 15 ppm 

has contributed to a change in R&D focus and emphasis to be more directed towards NOx adsorbers and urea 

SCR systems. However, the need to achieve approximately 90 percent conversion efficiency remains. Several 

developments will build upon and enhance the work completed this year:

• Availability of Prototype Engines: During the coming year, testing will be done using prototype CIDI 

engines which were not available before. These engines will not only have the latest in combustion and 

fuel injection system developments, but will be optimized to the latest emission control systems for CIDI 

engines. The emissions from these prototype engine and emission control systems should be a good 

indicator of the emissions performance of future CIDI vehicles. 

• Development of New Tools to Evaluate PM: PM emissions are strongly associated with CIDI engines and 

are implicated with causing significant health hazards. With more accurate measurement of PM it will be 

possible to identify their size and composition which will enable development of methodologies for further 

reductions and allow assessment of their health hazard relative to other fuels. It is especially important to 

be able to accurately measure the size distribution of ultra-fine PM, defined as PM smaller than 50 

nanometers. Ultra-fine PM has been implicated as a health hazard but the relative contribution from 

different types of vehicles has yet to be determined. In the coming year, Sandia National Laboratory will 

use their Laser Elastic Scattering (LIVES) technique to more accurately measure the soluble organic 

fraction of CIDI PM. Similarly, Lawrence Berkeley National Laboratory and Oak Ridge National 

Laboratory will use the Diesel Particulate Scatterometer they developed to more accurately characterize 

the size distribution of CIDI PM when using different fuels.

• Fundamental Combustion Research: Understanding the formation of PM and NOx holds the key to 

devising technology for limiting their production and subsequent control after leaving the engine. 

Formation of PM and NOx continue to be addressed on three separate fronts: 1) Sandia National 

Laboratory will use laser diagnostics that provide visual images of PM and NOx formation; 2) Lawrence 

Livermore National Laboratory is using chemical kinetics to predict the combustion reactions that form 

PM and NOx; and 3) advancements in computational fluid dynamics which are used to model air and fuel 

flow within the engine.

• Emission Control Device Research, Development & Testing: Previous work has identified several 

promising technologies for emission control devices to reduce PM and NOx emissions. The focus for the 

next year will be on how to improve the efficiency and durability of these devices. EPA has proposed that 

the sulfur content of diesel fuel be drastically reduced, but it is still uncertain what level is required to 

make most NOx emission control devices viable and durable for full useful life. Some of the specific 

activities that will be completed include:

- Build on the recommendations of the Sensor Workshop to develop cost-effective and rapid response 

sensors to detect NOx and PM for use in engine and emission system control.

- DDC will test a urea SCR catalyst system.

- Los Alamos will use a partial-oxidation reformer to make reductants for NOx adsorbers.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

7

- Sulfur traps may be needed for most NOx control devices even if the sulfur content of diesel fuel is 

reduced to the very low levels proposed by the EPA. Sulfur traps will be included in the testing 

planned of advanced emission control systems planned for the coming year.

- NOx emission control device technologies will be evaluated using diesel fuels having 8, 15, and 30 

ppm sulfur content.

- Initiate a project to estimate the cost of producing CIDI emission control systems.

- A contract was recently awarded to a team led by Ford to design and demonstrate a urea SCR NOx

emission control system (including PM control) for light-duty trucks.

• Development of Advanced Engine Components and Control Systems: Engine technology continues to 

advance with associated improvements in efficiency and emissions. The Advanced Combustion and 

Emission Control R&D Program is exploring advanced CIDI engine technologies on several fronts:

- Prototype pressure reactive pistons will be fabricated by Ford Motor Company and operated in singlecylinder test engines.

- A camless CIDI engine with electronic control of the valves will be tested and used to predict the 

benefits of electronic valve control for CIDI engines.

- Work will continue on advanced EGR systems that maximize the use of EGR over the speed and load 

range.

- New sensors that provide more accurate engine operating information more quickly will enable 

control of advanced emission systems. 

Honors and Special Recognitions

• Kevin Ott, Noline Clark, and Jon Ran of Los Alamos National Laboratory applied for a patent for their 

recent work on metal exchanged zeolite catalysts titled "Catalysts for Lean Burn Engine Exhaust 

Abatement."

• G. Hubbard, I. Shepherd, and A.J. Hunt of Lawrence Berkeley National Laboratory have applied for a 

patent for their Diesel Particulate Scatterometer.

• George Fenske’s research on near-frictionless coatings received the Innovative Research Award from the 

American Society of Mechanical Engineers-International in 1999. A patent related to this research, 

"Method to Produce Ultralow Friction Carbon Films," is pending.

• For their work on a microwave-regenerated exhaust particulate filter, Industrial Ceramic Solutions 

received the U.S. Small Business Administration’s "Administrator’s Award for Excellence" in recognition 

of outstanding contribution and service to the nation by a small business.

• Kevin Ott, Noline Clark, and Jon Ran of Los Alamos National Laboratory received the 2000 National 

Laboratory CIDI R&D Award in recognition of outstanding achievement in research and development of 

NOx catalysts for CIDI Engine Emission Control.

Conclusion

The remainder of this report highlights progress achieved during FY 2000 under the Advanced 

Combustion and Emission Control R&D Program. The following 19 abstracts of industry and National Lab 

projects provide an overview of the exciting work being conducted to tackle tough technical challenges 

associated with CIDI engines, including fuel injection, exhaust gas recirculation, fuel mixing, combustion 

processes, and catalytic exhaust treatment devices for controlling emissions. We are encouraged by the 

technical progress realized under this dynamic program in FY 2000. We also remain cognizant of the 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

8

significant technical hurdles that lie ahead, especially those presented for CIDI engines to meet the EPA Tier 2 

emission standards and proposed heavy-duty engine standards. In FY 2001, we look forward to working with 

our industrial and scientific partners to overcome many of the barriers that still stand in the way of delivering 

advanced automotive technology. We will also continue our close collaboration with the DOE Advanced 

Petroleum-Based Fuels Program to assure that the latest developments in fuels research are reflected in our 

work. 

Kenneth Howden, Program Manager Kathi Epping, Program Manager

Industry Combustion and Emission Control R&D National Laboratory Combustion and Emission Control R&D

Office of Advanced Automotive Technologies Office of Advanced Automotive Technologies

Office of Transportation Technologies Office of Transportation Technologies

Gurpreet Singh, Team Leader

National Laboratory Combustion and Emission Control

Office of Heavy Vehicle Technologies

Office of Transportation Technologies
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

9

II.EMISSION CONTROL SUBSYSTEM DEVELOPMENT 

A. Emission Control Subsystem Evaluation for Light-Duty CIDI Vehicles

Robert Yu (Primary Contact)

Cummins Engine Company

1900 McKinley Avenue

Columbus, IN 47201

(812) 377-7531, fax (812) 377-7226, e-mail: robert.c.yu@cummins.com

DOE Program Manager: Kenneth Howden

(202) 586-3631, fax: (202) 586-9811, e-mail: ken.howden@ee.doe.gov

Contractor: Cummins Engine Company, Columbus, Indiana

DOE Cooperative Agreement No. DE-CE02-00EE5077

Period of Performance: 7/1/99 through 12/31/01

Subcontractor: Engelhard Corporation, Iselin, NJ

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

4a. NOx Adsorber R&D

4f. R&D on Sulfur Trapping Technologies

5a. Catalyzed Diesel Particulate Filter

6. Prototype System Evaluations

Objectives

• Develop exhaust emission control system technologies applicable for LDV and LDT engines ranging 

from 55 kW to 200 kW.

• Deliver an optimized emission control subsystem for a 55 kW engine for PNGV applications to 

achieve the project goals of less than 0.20 g/mile oxides of nitrogen (NOx) and 0.018 g/mile particulate 

matter (PM) with engine-out emissions of 1.4 g/kW-hr NOx and 0.15 g/kW-hr PM. Only those 

technologies which have a reasonable chance (with further development beyond the scope of this 

program) of meeting the EPA Tier 2 fleet average regulation of 0.07 g/mile NOx and 0.01 g/mile PM 

will be pursued.

• Develop diesel injector nozzles with small spray holes (20 to 100 microns in diameter), and 

piezoelectric technology for fast transient response, and variable control of injection rate shape.

 Approach

• Under this program, various NOx emission control technologies including non-thermal plasma, NOx

adsorbers, and active lean NOx catalysts, in conjunction with active reductant injection will be 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

10

investigated to meet the NOx emission objective. At the end of the seventh month (milestone 1), a 

decision will be made to select the best NOx control technology for PNGV emission control subsystem 

integration and development. The areas of development include catalyst formulation for high NOx

conversion over a wide catalyst/exhaust gas temperature range, catalyst structure for increased exhaust 

gas residence time on active catalyst sites, and an understanding of the various factors that cause 

deactivation of the catalyst. Fuel reformulation concepts and diesel fuel based onboard hydrocarbon 

cracking strategies will be investigated to increase the activity of the hydrocarbons introduced into the 

catalyst systems as reductants. Even with the availability of 15 ppm sulfur fuels, the development of a 

sulfur management scheme is critical to prevent catalyst poisoning and deactivation. The application 

of a sulfur trap that can be regenerated or periodically replaced will be explored.

• PM emissions will be addressed by developing a catalyzed soot filter or a combination of catalyzed 

soot filters with supplemental microwave heating. Soot filter catalysts have been successfully 

formulated for heavy-duty applications with passive regeneration. However, with the lower exhaust 

temperatures encountered in PNGV-type vehicle applications, an active regeneration scheme with 

supplemental heating will be investigated.

• Finally, the improved emission control components will be integrated and configured optimally in a 

system developed for a PNGV-type vehicle. This system will then be calibrated and tested in a 

controlled environment on a PNGV-sized engine.

Accomplishments 

• The development of a vehicle/engine/emission control system performance model has been 

completed, and the model is being used in conjunction with critical lab/engine experiments for 

preliminary emission control device subsystem design and analysis. 

• The results of preliminary exhaust emission control device subsystem design and analysis indicated 

that the best NOx control approach for LDV and LDT applications is the NOx adsorber catalyst. NOx

device reduction efficiencies of 65% and 87% are required to achieve 0.20 g/mile and 0.07 g/mile 

PNGV vehicle-out emissions, respectively.

• At the third program review, a decision was made to select the NOx adsorber catalyst as the NOx

control technology for exhaust emission control device subsystem integration and development.

• Two DIATA engines have been received, and one has been assembled into a test skid that is near 

completion. The test skid will allow the relatively small DIATA engine to fit into Cummins’ test cells. 

The test skid, including DIATA engine, dynamometer, coupling, heat exchangers, and some electronic 

controls, will be able to be installed into a test cell with a minimum changeover time. Three low 

emission Cummins ISB breadboard engines have been procured and are being used extensively for 

emission control system model development and catalyst performance mapping.

• Among all the engine exhaust characteristics, exhaust temperature plays the most dominant role on 

exhaust emission control device performance. A correlation of engine-out NOx as a function of exhaust 

gas temperature for the FTP-75 cycle has been done to guide the exhaust emission control device 

development work.

• Progress has been made on identifying the best reductant for NOx adsorber catalysts. The results 

indicate that H2 is the best reductant, followed by a mixture of H2 and CO, followed by CO. Short 

straight chain (C4-C8) hydrocarbons are not good reductants. 

• Significant effort is underway to develop and acquire the catalyst system and HC enrichment control 

hardware for system model validation and to conduct transient FTP-75 results on the prototype 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

11

hardware. A Dodge/ISB vehicle will be used for LDT evaluation, and a mobile emission control 

system will be designed and used for LDV evaluation on a DIATA engine. 

Future Directions

• Develop and optimize selected catalyst formulations for best NOx conversion efficiency under exhaust 

temperatures and space velocities consistent with anticipated PNGV application.

• Develop and design an irreversible sulfur trap to provide sufficient capacity to trap 100% of the fuel 

and oil derived SOx for greater than 10,000 miles of operation. 

• Identify the optimum reductant derived from diesel fuel and develop the reductant injection system.

• Construct and integrate the reductant enrichment control hardware with the emission control system in 

test cell.

• Optimize the reductant control for enrichment during steady-state and transient operations for best 

exhaust emission control device performance (conversion efficiency, fuel penalty, and HC slip). 

• Develop and optimize the NOx/PM system configuration. Changes that will be explored include the 

order of PM and NOx catalyst placement, injections between bricks, and full-flow versus by-pass 

regeneration.

Overview

The proposed EPA Tier 2 fleet average NOx

standards will be more stringent than the PNGV 

target. As a result, the need to bring the NOx goals for 

the cooperative agreements into harmony with the 

EPA regulations required that modification be made 

to the program targets. Cummins has agreed to 

modify the existing targets to include an interim NOx

target of less than 0.20 g/mile and a stipulation that 

only those technologies which have a reasonable 

chance (with further development beyond the scope 

of this program) of meeting EPA Tier 2 regulations 

be pursued. The program’s primary focus will be on 

exhaust emission control subsystem NOx and PM 

conversion efficiency, although the higher 

conversion efficiency required may result in an 

increase in the cost, size, and weight of the exhaust 

emission control subsystem.

The key objective of this project is to develop the 

generic exhaust emission control technologies 

applicable for LDV and LDT engines ranging from 

55 kW to 200 kW. This will involve engines with 

displacement ranging from 1.2 liters to 6.0 liters. A 

fundamental and "displacement-size" transparent 

understanding will be required. Cummins’ results 

indicate that the LDV and LDT exhaust operating 

characteristics can be simulated with the Cummins 

ISB mule engines (see Figure 1). Therefore, most of 

the exhaust emission control subsystem screening 

and fundamental understanding will be conducted on 

the ISB mule engines. In addition, parallel 

performance validation and final system 

optimization will be conducted on a PNGV-sized 

engine approved by DOE. Cummins is planning to 

use the DIATA engines, developed under the Ford 

Hybrid Propulsion System Development Program, as 

the focus of this project (see Figure 2) Cummins will 

utilize DIATA engine data and PNGV target vehicle/

engine-out emissions to determine the input 

specifications for modeling and design optimization. 

This effort is required to provide evidence through 

modeling that the results recorded from engine 

dynamometer testing can be expected to meet the 

Figure 1. Cummins ISB Engine
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

12

vehicle emission requirements. Figure 3 is a detailed 

flow chart of the activities described above.

Approach

The targeted NOx reduction levels are difficult to 

achieve. Sulfur poisoning, thermal aging, catalyst 

masking, and hydrothermal aging are critical areas 

requiring investigation. In addition, effective use of 

reductants will be a key area of this investigation. 

NOx adsorber catalysts have shown the high NOx

reduction levels using low-sulfur fuels under steadystate conditions. Effective regeneration during 

transient operation at low temperatures and NOx

reduction without exceeding PM limits are critical 

hurdles. Plasma assisted catalytic reduction has also 

demonstrated high NOx reduction levels at low space 

velocities and temperatures similar to an automotive 

application. The principle of the non-thermal plasma 

for NOx control is to pass the exhaust gas through a 

reaction chamber where a rapid electrical pulse of 

short duration (25 kV, 28mHz, 10 nanosecond) is 

introduced. Plasma devices have two major 

attributes: the first is the ability to modify the NO2 to 

NO ratio and the second is the generation of active 

hydrocarbon-based species for NOx reduction. Major 

hurdles for this technology include electrical power 

management, complexity, safety, and catalyst 

effectiveness. With the combination of low-sulfur 

fuel, and the lower operating temperatures of the 

PNGV-type engines compared to heavy-duty diesel 

engines, investigation of higher platinum content 

NOx reduction catalysts using the lean NOx approach 

also holds promise as a solution for NOx reduction.

The major milestones of the program are as 

follows:

• 7 months-results of performance model and 

preliminary exhaust emission control device 

subsystem hardware design.

• 15 months-test results on exhaust emission 

control prototype hardware and/or component 

tests and updated modeling results.

• 34 months-delivery of complete exhaust 

emission control subsystem suitable for 

evaluation with a 55 kW PNGV-type engine to 

ORNL.

Results

In Phase I of this project, the three NOx reduction 

technologies including plasma assisted catalytic NOx

reduction, active lean NOx catalysis, and adsorber 

catalyst technology using intermittent rich conditions 

for NOx reduction were investigated in parallel in an 

attempt to select the best NOx control approach for 

PNGV exhaust emission control subsystem 

integration and development. These included critical 

lab/engine experiments, preliminary design and 

Figure 2. Ford DIATA Engine

Figure 3. Flowchart of Project Activities
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

13

analysis, and ranking and selection of NOx control 

technologies against reliability, up-front cost, fuel 

economy, service interval/service hassle, and size/

weight.

Figure 4 illustrates the NOx conversion 

efficiency of three different adsorber catalysts. 

These catalysts illustrate the potential for high NOx

conversion over a fairly wide temperature range of 

catalyst inlet temperatures of 250o

C to 400oC. 

However, in light-duty applications catalyst inlet 

temperatures are often below 250o

C. An advantage 

of these catalysts is that they can use diesel fuel as a 

reductant. These catalysts need ultra-low sulfur 

content fuel - conversion efficiency was observed to 

deteriorate at the rate of 0.1% per hour using diesel 

fuel with 11 ppm sulfur content.

Control of PM emissions was demonstrated 

using a catalyzed soot filter (CSF). Figure 5 

illustrates the capability of the CSF to reduce PM as 

a function of catalyst temperature. This device has 

the added advantages of providing reduction in HC 

and CO emissions, and being sulfur tolerant.

Conclusions

The results of preliminary exhaust emission 

control subsystem design and analysis indicated that 

the best NOx control approach for LDV and LDT 

applications is the NOx adsorber catalyst. NOx

reduction efficiencies of 65 % and 87 % are required 

to achieve 0.20 g/mile and 0.07 g/mile NOx PNGV 

vehicle-out emissions, respectively. Both active lean 

NOx and PACR technology are not capable of 

achieving the high conversion efficiency required for 

DOE/PNGV program objectives. The best NOx

conversion efficiency achieved for active lean NOx

and PACR was about 40 %. Some of the key findings 

are summarized below:

(A) Active Lean-NOx Catalyst

 Positives

• Can use diesel fuel as reductant (diesel fuel 

can be added to the exhaust gases or done incylinder).

• A 40 % NOx conversion efficiency was 

demonstrated with diesel fuel as an injection 

reductant.

• Simple injection strategy with low 

complexity for implementation.

• Potential low cost solution for very clean 

diesel fuel (i.e., low-sulfur) with ultra-low 

engine-out emissions (less than 1.4 g/kW-hr 

NOx).

• Precious metal catalyst is only slightly 

inhibited by H2O.

 Negatives

• High NOx conversion to N2O (about 50%-

60% of the NOx reduced); N2O is a strong 

greenhouse gas.

• High sulfate formation rates at high 

temperatures for high-sulfur fuel. Not an 

issue with future low-sulfur fuel.

• Need combination of different catalysts to 

cover the whole exhaust temperature range 

for FTP-75 and US-06 cycles.

Figure 4. NOx Conversion Efficiencies for Three 

Different Adsorber Catalysts

Figure 5. PM Emission Control from Catalyzed Soot 

Filter
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

14

(B) Plasma Assisted Catalytic Reduction (PACR) 

 Positives

• Conversion of NO to NO2 at low 

temperatures, without SO2 to SO3 oxidation.

• Can enhance NOx conversion at low 

temperatures.

• Can use diesel fuel as a reductant.

• Simple reductant injection strategy similar to 

active lean NOx catalyst.

 Negatives

• Additional power required for plasma 

generation.

• Very low space velocity/very large catalyst 

volume required for high conversion 

efficiency; a 40% NOx reduction was 

achieved with a 90 liter Gamma-Alumina 

catalyst.

• Potential safety issues due to high voltage/

possible EMI generation.

• Benefit of non-thermal plasma decreased as 

the temperature is increased. No benefit was 

observed at temperatures greater than 280o

C.

• Evidence of NOx adsorption as significant 

NOx consumption pathway. The catalyst 

would adsorb NOx at low temperatures (200-

250o

C) and would desorb NOx at higher 

temperatures (400-450o

C).

(C) NOx Adsorber Catalyst

 Positives

• Potential for high NOx conversion (>80%).

• Wide temperature range of peak operation 

(250o

C to 400oC), yet not low enough for 

light-duty applications.

• Can use diesel fuel as a reductant.

• No infrastructure issues (as with urea 

distribution).

 Negatives

• Rapidly poisoned by sulfur in the fuel and 

lube, and NOx conversion efficiency 

decreases at a rate of approximately 0.1 % 

per hour with 11 ppm sulfur fuel; a sulfur 

trap will be required.

• Rich operation of injected hydrocarbon 

leading to high fuel penalty, HC slip, and 

SOF particulate production.

• Partial flow regeneration adds complexity 

but offers lower fuel economy penalty.

• High cost due to high precious metal catalyst 

loading.

• Complex reductant injection/control system.

List of Publications

1. Frank F. Mao and C.Z. Wan, "Fundamental of 

Sulfur Trap for Diesel Engine Emission 

Control," being prepared for Diesel Engine 

Emission Reduction Workshop, San Diego, CA, 

August 2000.

2. Matthew J. De Witt and C Z Wan, "Establishing 

Capabilities to Evaluate Reductants for NOx

Adsorber Technologies," being prepared for 

Diesel Engine Emission Reduction Workshop, 

San Diego, CA, August 2000.

3. R. Mital, Shyan Huang, Bradlee Stroia, and C Z 

Wan, "Lean NOx Technology for Diesel 

Emission Control," being prepared for Diesel 

Engine Emission Reduction Workshop, San 

Diego, CA, August 2000.

List of Acronyms

CSF Catalyzed Soot Filter

DIATA Direct Injection Aluminum 

Through-Bolt Assembly

ISB Integrated System B (a fully 

electronic, 24-valve inline 6-

cylinder B family engine)

LDV Light-Duty Vehicle

LDT Light-Duty Truck

ORNL Oak Ridge National Laboratory

PACR Plasma Assisted Catalytic Reduction

PNGV Partnership for a New Generation of 

Vehicles

PM Particulate Matter
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

15

B. Application of Advanced Emission Control Sub-Systems to State-of-the-Art 

Diesel Engines

Houshun Zhang (primary contact), Brian Bolton

Detroit Diesel Corporation (DDC)

13400 West Outer Drive 

Detroit, MI 48239-4001

(313) 592-9815, fax: (313) 592-7888, e-mail: houshun.zhang@detroitdiesel.com

DOE Program Manager: Kenneth Howden

(202) 586-3631, fax: (202) 586-9811, e-mail: ken.howden@ee.doe.gov

Contractor: Detroit Diesel Corporation, Detroit, Michigan

DOE Cooperative Agreement No. DE-CE02-00EE5075

Period of Performance: 7/1/99 through 12/31/01

Subcontractors: Engelhard Corporation; Michigan Technical University (MTU), Houghton, MI

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

4. NOx Control Device R&D

5. Particulate Matter Control Device R&D

6. Prototype System Evaluations

Objectives

• Demonstrate technology for PNGV/Personal Transportation (PT) CIDI engine families of 0.5L/

cylinder to ~0.7L/cylinder displacement, which will achieve DOE emissions targets for 2004 and 

2007.

• Meet specific targets for engine-out emissions, efficiency, power density, noise, durability, production 

cost, and emission control sub-system volume and weight.

Approach

• Fundamentally pursue an integrated engine, emission control system and vehicle approach using a 

coupled experimental and analytical tool set.

• Develop comprehensive engine sub-system emission control models for emissions prediction.

• Integrate the sub-models into a global model for application over a wide range of time domains.

• Select and evaluate best (engine+emission control) system.

• Conduct system performance, emissions and durability evaluation testing.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

16

Accomplishments

• Developed three-layer integrated engine+emission control virtual lab technical roadmap describing 

0D, 1D and 3D paths and tool integration.

• Emission control, engine, vehicle and control system models described in the integrated roadmap are 

under development.

• SCR 3D transient CFD modeling is underway.

• Initial vehicle integrated SCR benchmark experimental testing is underway.

• Progress has been made on the PM model including 2D modifications and integration of new filtration 

and pressure drop elements.

• An engine setup is completed and engine-out emissions characterization is underway.

• Initiated catalyst aging tests.

Future Directions

• Complete initial version of three-layer integrated engine/emission control tool sets.

• Adapt combustion system for lowest possible engine-out emissions while simultaneously improving 

aftertreatment inlet temperature conditions for improved catalyst efficiency. Expand the synergistic 

engine+emission control coupling to include relevant emission-critical operating regions.

• Benchmark integrated engine+emission control system using best available technology to assess 

transient emission reduction potential and challenges.

Introduction

DDC is conducting the Low Emissions 

Aftertreatment and Diesel Emissions Reduction 

(LEADER) program under a DOE project titled: 

"Research and Development for CompressionIgnition Direct-Injection Engines (CIDI) and 

Emission Control Subsystem." LEADER is a 36-

month program to develop emission control 

technologies on vehicles and demonstrate scalability 

for various vehicle inertia classes. DDC has 

significant experience in light-duty diesel engine 

development and has developed unique engines with 

displacements varying from 0.5L to 0.67L per 

cylinder for different applications. Figure 1 

illustrates the scaling for advanced light-duty CIDI 

engines in personal transportation vehicle platforms.

Approach

The overall technical roadmap and approach are 

schematically summarized in Figure 2. The 

experimental transient FTP emission testing 

milestones shown will be supported by an integrated 

engine, emission control system, and vehicle 

approach using a coupled experimental and 

analytical tool set. DDC and its subcontractors will 

develop a suite of advanced integrated catalyst and 

engine emission control models that predict 

quantitative emissions for a broad range of engineout conditions and catalyst design specifications. 

These models will be integrated in a seamless 

fashion over a range of spatial resolutions. This tool 

will probe for the best combinations of emission 

control configurations and operating environments. 

Engine and vehicle test data will be used to validate 

Figure 1. Personal Transportation Engine Technologies
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

17

the integrated models, thus providing further design 

recommendations and testing directions. Final 

selection and evaluation of the best engine+catalyst 

technology combinations will be tested in vehicles. 

A schematic of the development process is shown in 

Figure 3.

Results

4SDI peer review meetings were held that 

updated the program status and direction.

Engine tests were set up at DDC focusing on 

probing engine-out emissions reduction. This 

includes the combustion system, fuel injection 

system and EGR system.

Following a comprehensive literature search of 

emission control system data, analytical model 

development is underway. DDC is developing a 

methodology to integrate various catalyst models 

into a comprehensive engine+emission control 

system model, thereby addressing engine, vehicle 

performance, and emissions in an integrated fashion. 

Displayed in Figure 4 is the virtual lab technical path. 

It features a three-layer development strategy 

ranging from complicated three-dimensional fluid 

dynamics and chemistry focusing on detailed 

geometry design to a simplified zero-dimensional 

model focusing on overall system control strategies.

An example of this three-layer development 

strategy is a 3D transient simulation of urea spray 

injection used for a SCR system applied to the 0.5 

liter per cylinder platform. This particular example 

evaluates the spray system: investigating wall 

interaction, droplet break-up and coalescence, and 

evaporation. Further, it provides quantitative 

comparison of spatial and temporal evaporated urea 

distribution to the catalyst under realistic operating 

conditions. Figure 5 shows the urea distribution 

along the exhaust pipe using 2.5 msec "snapshots" of 

droplet distribution and vaporized concentration. It 

can be seen that under these conditions limited 

droplet vaporization is achieved, and non-uniform 

Figure 2. Program Technical Roadmap

Figure 3. Engine/Emission Control Development Flow 

Chart

Figure 4. Emission Control Virtual Lab Technical Path 

and the Three Layer Interactions

Figure 5. Modeling of Urea Spray Distribution using 

Three-Dimensional Tool
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

18

urea delivery to the catalyst element is observed. 

This is an example of how the 3D version of the 

virtual lab tool will allow a compact, integrated 

vehicle solution with minimum compromise to 

system performance.

Michigan Technological University is 

progressing on the PM model development. The 2D 

model modifications were completed and the model 

was integrated with AGK’s filtration and pressure 

drop models. The integrated model has been 

validated against different filters. With this 

enhancement, the PM model accurately predicts the 

pressure drop in different PM filters. Figure 6 

compares the predicted pressure drop with 

experimental data for a specified filter. The solid line 

is the simulation result and the dots represent the 

experimental data. Excellent correlation was 

observed. In particular, the ability to predict the 

initial transient loading behavior of the filter’s 

pressure drop was demonstrated. Additional activity 

at MTU includes updating the energy equation 

numerical algorithm and including species equations 

to model NO2 soot oxidation kinetics. A detailed 

experimental database has been established.

Conclusions and Future Directions

Detroit Diesel Corporation and its subcontractors 

are developing a comprehensive simulation suite for 

a high-fidelity simulation of the integrated CIDI 

engine-emission control systems for personal 

transportation light-duty vehicles. Preliminary subsystem models are being developed and exercised. 

An integrated (PM + NOx) baseline emission control 

system will be tested on a vehicle chassis 

dynamometer using urea-based SCR as the NOx

emission control technology, and a catalyzed DPF as 

the PM emission control technology. These catalyst 

technologies are the prime path for the program, 

although a NOx adsorber will also be studied as an 

alternative to SCR. The program technical approach 

was further verified with input from DDC, its 

subcontractors, and the 4SDI peer review team. 

Progress on the analytical models show good 

correlation with experimental results.

List of Acronyms

4SDI 4-Stroke Direct Injection

AGK A.G. Konstandopoulos

BC Boundary Condition

CFD Computational Fluid Dynamics

CIDI Compression-Ignition DirectInjection Engines

CRT Continuous Regeneration Trap

DDC Detroit Diesel Corporation

DOE Department of Energy

DPF Diesel Particulate Filter

EGR Exhaust Gas Recirculation

FTP Federal Test Procedure

HEV Hybrid Electric Vehicle Engine

IC Initial Condition

FIE Fuel Injection Equipment

LEADER Low Emissions Aftertreatment and 

Diesel Emissions Reduction

MTU Michigan Technological University

NOx-ADS NOx Adsorber

PM Particulate Matter

PNGV Partnership for a New Generation of 

Vehicle

PT Personal Transportation

SCR Selective Catalytic Reduction

SFTP Supplemental Federal Test 

Procedure

VGT Variable Geometry Turbo

Figure 6. Comparison of the Predicted Pressure Drop by 

the Transient Filtration Model against the 

Experimental Data for a Filter
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

19

III. IN-CYLINDER COMBUSTION STUDIES, ADVANCED 

COMBUSTION RESEARCH, SENSORS, AND DIAGNOSTICS 

A. Heavy-Duty Diesel Engine Combustion: Diffusion-Flame/Wall Interactions

John E. Dec

Sandia National Laboratories

P.O. Box 969, MS 9053

Livermore, CA 94551-9699

(925) 294-3269, fax: (925) 294-1004, e-mail: jedec@sandia.gov

DOE Program Manager: Gurpreet Singh

(202) 586-2333, fax (202) 586-1600; e-mail: gurpreet.singh@hq.doe.gov

Contractor: Sandia National Laboratories, Livermore, CA

Contract Number: DE-AC04-94AL85000

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

3a. Identification of Advanced Combustion Systems

Objectives

• The overall objective of this project is to advance the understanding of diesel engine combustion and 

emissions formation through the application of advanced laser-based diagnostics.

• Specific objectives for FY 2000:

- Investigate diffusion-flame/wall interactions in a heavy-duty DI diesel engine and determine the 

potential of soot-deposition on the wall as a pathway to soot emissions.

- Perform complete relocation of the Heavy-Duty Diesel Engine Laboratory to CRF Phase II, and 

make numerous upgrades.

Approach

• Investigation of diffusion-flame/wall interactions:

- Develop an optical setup for imaging the leading edge of the combusting fuel jet as it impinges on 

the combustion-bowl wall in the Sandia/Cummins optically accessible engine.

- Obtain high-resolution OH PLIF (planar laser-induced fluorescence) images of the diffusion flame 

during wall interaction.

- Set up a dual-laser, dual-camera system to simultaneously image the OH-radical and soot 

distributions during jet/wall interaction to assess the likelihood for soot deposition.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

20

Accomplishments

• Conducted a detailed investigation of the behavior of the reacting fuel jet as it encounters the 

combustion-bowl wall.

- Acquired simultaneous OH-PLIF and PLII-soot images showing that prior to contacting the wall, 

the soot is completely contained by an intact diffusion flame.

- Acquired images of the diffusion flame showing that the flame first remains active as the leading 

edge of the jet deforms and flattens along the wall surface, but that within 70 μs the flame is 

extinguished along the entire front of the jet that is against the wall.

- Showed that after the flame is extinguished by the wall, the soot-filled central region of the jet 

impinges directly on the wall surface, offering a potential pathway for soot emissions, i.e. wall 

deposition and eventual blow-off into the exhaust.

Future Directions

• Extend the jet/wall interaction study to include measurements of soot deposition rates to provide an 

estimate of the significance of this pathway to the total soot emissions.

• Establish an improved vertically oriented line-of-sight (LOS) extinction diagnostic to obtain a 

quantitative measurement of the total bulk-gas soot during the late-combustion soot burnout period.

- Obtain measurements over a range of operating conditions and compare results with previous 

engine-out and late-combustion PLII-soot image data.

• Use PLII to image the soot directly under the exhaust valve during blow-down and the exhaust stroke 

to determine the time-history of soot emissions from the cylinder.

- Correlate results with late-combustion LOS and PLII image data to help understand the 

contributions of the various pathways to soot emissions.

Introduction

Although laser diagnostics have improved our 

understanding of many aspects of diesel combustion, 

the interactions between the combusting fuel jet and 

the piston-bowl wall are not well understood. In 

heavy-duty engines these interactions occur with the 

combusting vapor-phase region of the jet, which 

consists of a central region containing soot and other 

products of rich-premixed combustion, surrounded 

by a diffusion flame [1]. If the diffusion flame is 

extinguished by the wall interaction, soot could be 

deposited on the wall and subsequently blown off, 

becoming an engine-out emission. Diffusion-flame 

quench at the wall would also reduce the burning rate 

and the rate of NOx formation as the flame surface 

area is reduced.

The objective of the current work is to 

investigate the behavior of the diffusion flame as it 

contacts the wall, and to determine whether jet/wall 

interaction provides a means for soot to escape 

combustion and become an engine-out emission. 

This investigation, and all of the work on this project, 

are conducted in cooperation of our CRADA 

partners (Cummins, Caterpillar, and Detroit Diesel), 

and the results are presented at the cross-cut diesel 

CRADA meetings.

Approach

Laser-sheet imaging diagnostics provide a means 

to directly examine the behavior of the diffusion 

flame and soot distributions as the jet interacts with 

the wall. Since previous work has shown that the 

OH radical is a good marker of the diffusion flame 

during diesel combustion [2], planar laser-induced 

fluorescence (PLIF) imaging of OH was applied to 

the current investigation of the diffusion-flame/wall 

interaction. In addition, simultaneous OH PLIF and 

planar laser-induced incandescence (PLII) soot 

imaging was used to investigate the likelihood for 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

21

soot deposition on the bowl wall. The Sandia/

Cummins optically accessible heavy-duty diesel 

engine was used to apply these diagnostics in a 

realistic diesel environment. Obtaining these images 

required developing a new optical setup with a quartz 

window in the piston bowl-rim, in-line with one of 

the cylinder-wall windows of the optical engine.

Prior to conducting this investigation of the jet/

wall interaction, it was necessary to enhance the 

capability of the engine-support and other laboratory 

subsystems using up-to-date computerized-control 

and data-acquisition technology, as appropriate.

Results

A schematic of the optical setup used for the OHPLIF imaging of the diffusion flame during wall 

interaction is shown in Figure 1. As shown in the 

figure, a portion of the piston bowl-rim was replaced 

with a quartz window, and the laser sheet passes 

through both the cylinder-wall window and the bowlrim window before intersecting the leading edge of 

the fuel jet as it approaches, and then encounters, the 

wall. Images were acquired through the cylinderhead window with the 30 by 22 mm field-of-view 

shown in the right-hand schematic of Figure 1.

Figure 2 shows a temporal sequence of OH PLIF 

images of the leading portion of the jet as it 

encounters the wall. Note that for all the data 

presented, TDC is taken to be 360o

, and fuel injection 

starts at 348.5o

 (11.5o before TDC). As shown in 

previous works [1,2], measurable quantities of OH 

occur only in a very narrow region around the jet 

periphery, marking the location of the diffusion 

flame. This is evident in Figure 2 as the thin, bright 

region around the edge of the jet. The curved bowlwall is also faintly visible just in front of the leading 

edge of the jet in the 356.5o

 and 357.0o images. The 

white horizontal lines in these images show the "cutlines" used for the intensity plots below the images.

Prior to encountering the wall, the images show 

that the diffusion flame is completely intact around 

the leading edge of the jet (see the 356.5o

 and 357.0o

images). However, shortly after the jet impinges on 

the wall, portions of the flame begin to go out as seen 

in the 357.5o

 image. By 358.0o, the flame has been 

extinguished along the entire front of the jet that is 

against the wall. These steps of flame extinction are 

shown in a more quantitative way by the "cut-line" 

intensity plots. At 356.5o

 the diffusion flame is 

evident as the narrow, high-intensity spike at about 

pixel 265, and the wall location shows up as the 

much smaller spike at about pixel 280. By 357.5o

, 

the flame is against the wall in some regions and is 

beginning to go out, as evident in the upper intensity 

plot, corresponding to the upper cut-line. In other 

regions, such as the location of the lower cut-line, the 

flame is still strong and slightly separated from the 

wall. However, within about 70 microseconds of 

encountering the wall (358.0o

 image) the flame has 

gone out along the entire region that is against the 

wall, and the plot shows only the low-intensity wall 

spike.

Greater detail of the diffusion-flame/wall 

interaction may be seen in Figure 3, which presents 

Figure 1. Schematic of the combustion chamber showing 

the laser orientation and field of view

Figure 2. Temporal sequence of OH-PLIF images of the 

diffusion flame (360o = TDC). The jet is 

flowing from left to right, and the curve at the 

left shows the edge of the cylinder-head 

window (see Figure 1). The horizontal white 

lines (10 mm long) show the location of the 

intensity plots. The field of view is 30 by 22 

mm.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

22

images from different engine cycles, all taken at 

357.5o

. Due to small variations in injection timing 

and turbulence, jet penetration varies somewhat from 

cycle to cycle. The images in Figure 3 have been 

arranged in order of apparent penetration. These 

images show that as the jet encounters the wall, the 

leading edge deforms, flattening the diffusion flame 

along the wall surface. Despite being close to the 

wall, the flame remains active for a short time before 

being extinguished along the entire front of the jet 

that is against the wall.

The optical setup for the simultaneous OH-PLIF 

and PLII-soot images is shown in Figure 4. The 

beams of the 284 nm, ultra-violet laser (for OH 

PLIF) and the 532 nm doubled Nd:YAG-laser (for 

PLII-soot) are combined into overlapping laser 

sheets by a series of lens and a custom dichroic 

mirror. The two image types are captured on two 

separate intensified CCD cameras, with the signal 

being split between the two cameras by another 

dichroic mirror. The OH and soot images are then 

mapped with separate false color schemes before 

each image pair is combined into a single image 

using a special color table.

Figure 5 presents a temporal sequence of the 

combined, simultaneous OH and soot images. When 

printed in black and white, the soot region in the 

central part of the jet appears as dark gray, while the 

OH region around the jet periphery shows up as light 

gray. These images show that after the diffusion 

flame is extinguished at the wall surface, the soot 

within the combusting jet impinges directly on the 

wall. This allows the soot to be deposited on the wall 

surface and escape combustion.

Conclusions

A detailed investigation of the jet/wall 

interaction in a heavy-duty diesel engine has been 

conducted using laser-sheet imaging. The data show 

that the diffusion flame at the jet periphery is 

extinguished by the wall, allowing the soot-filled 

central region of the jet to impinge directly on the 

wall surface. This provides a potential pathway for 

Figure 3. A series of OH-PLIF images at 357.5o taken 

from different engine cycles. The curve at the 

left shows the edge of the cylinder-head 

window, and the bowl wall is shown by the 

white curve at the right in the first five images.

Figure 4. Optical setup for simultaneous OH-PLIF and 

PLII-soot imaging.

Figure 5. Temporal sequence of simultaneous OH and 

soot images. The curve at the left marks the 

edge of the window and the curve at the right 

marks the bowl wall.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

23

soot emissions, i.e. wall deposition and eventual 

blow-off into the exhaust. The flame extinction at 

the bowl wall will also have an impact on 

combustion and NOx formation rates.

The results of this investigation improve our 

understanding of the mechanisms behinde a 

potentially significant, but largely unexplored, 

additional pathway to soot emissions. As engine 

manufacturers strive to produce engines with 

extremely low emissions, all potential mechanisms 

must be understood. This allows the manufacturers 

to develop correct engineering models and to better 

focus their development efforts on appropriate areas. 

In addition, the understanding of the effects of walls 

on reacting diesel fuel jets (and the associated impact 

on combustion, soot emissions, and NOx formation) 

provides information necessary for the development 

of more active predictive-numerical-models of diesel 

combustion.

Relocation of the Heavy-Duty Diesel Engine 

Laboratory has been completed, and the laboratory in 

now is fully operational in its new location.

List of References

1. Dec, J. E., "A Conceptual Model of DI Diesel 

Combustion based on Laser-Sheet Imaging," 

SAE Transactions, Vol. 106, Sec. 3, pp. 1319-

1348, paper no. 970873, 1997.

2. Dec, J. E. and Coy, E. B. "OH Radical Imaging 

in a D.I. Diesel Engine and the Structure of the 

Early Diffusion Flame," SAE Transactions, Vol. 

105, Sec. 3, pp. 1127-1148, paper no. 960831, 

1996.

List of Publications/Presentations

1. Dec, J. E. and Kelly-Zion, P. L., "The Effects of 

Injection Timing and Diluent Addition on LateCombustion Soot Burnout in a DI Diesel Engine 

based on Simultaneous 2-D Imaging of OH and 

Soot," SAE paper no. 2000-01-0238, presented 

at the SAE Congress, Mar. 2000.

2. Dec, J. E. and Kelly-Zion, P. L., "An 

Investigation of Late-Combustion Soot Burnout 

in a DI Diesel Engine using Simultaneous Planar 

Imaging of Soot and OH Radical," presented at 

and published in the proceedings of the DEER 

Workshop, Castine, ME, July 1999.

3. Dec, J. E., Canaan, R. E., and Tree, D. R., "The 

Effect of Water-Emulsified Fuel on Diesel Soot 

Formation," presented at and published in the 

proceeding of the 219th American Chemical 

Society National Meeting, San Francisco, CA, 

Mar. 2000.

4. Dec, J. E., Diesel Combustion Progress Report, 

Cross-Cut Diesel CRADA Meeting, Oct. 1999.

5. Dec, J. E., Diesel Combustion Progress Report, 

Cross-Cut Diesel CRADA Meeting, Jan. 2000.

6. Dec, J. E., "A Conceptual Model of DI Diesel 

Combustion and its Relationship to Potential 

Investigations of Enhanced Autoignition," 

presented to the Ethyl Corporation, Mar. 2000.

7. Dec, J. E. and Tree, D. R., "Heavy-Duty Diesel 

Engine Combustion: Diffusion-Flame/Wall 

Interactions," DOE CIDI Combustion, Emission 

Control, and Fuels Review, May 2000.

8. Dec, J. E., "An Overview of Heavy-Duty Diesel 

Engine Research at Sandia," presented to a joint 

meeting of Ricardo North America and Universal 

Oil Products, May 2000.

9. Dec, J. E., "An Understanding of DI Diesel 

Combustion and Soot Burnout based on LaserSheet Imaging," presented to the Lubrizol 

Corporation, May 2000.

10. Dec, J. E. and Tree, D. R., "Diffusion-Flame/

Wall Interactions in a Heavy-Duty DI Diesel 

Engine," Cross-Cut Diesel CRADA Meeting, 

May 31 - June 1, 2000.

List of Acronyms

CRADA Cooperative Research and 

Development Agreement

CRF Combustion Research Facility

DI Direct Injection

FY Fiscal Year

LOS Line of Sight

PLIF Planar Laser-Induced Fluorescence

PLII Planar Laser-Induced Incandescence

TDC Top Dead Center 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

24

B. Development of a Combined Mass Flow Rate and Chemical Composition 

Sensor for the Intake of CIDI Engines Using Thin Film MEMS Sensors

Dr. Darby B. Makel

Makel Engineering, Inc.

1020 Marauder Street, Suite D

Chico, CA 95973

(530)895-2771, fax: (530) 895-2777, e-mail: dmakel@makelengineering.com

DOE Program Manager: Donna Lee Ho

(202) 586-8000, fax: (202) 586-9811, e-mail: Donna.Ho@ee.doe.gov

Contractor Makel Engineering, Inc., Chico, California

DOE Contract Number:DE-FC02-00EE50628; Period of Performance:4/1/00 to 3/31/00

Subcontractors: Case Western Reserve University, Cleveland, Ohio (Dr. C.C. Liu); University of California, Berkeley, Berkeley, California (Dr. Robert Dibble)

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

2. Sensors and Controls

Objectives

• Phase I:

- Design and fabricate a prototype sensor using MEMS technology.

- Perform laboratory feasibility tests.

- Perform application feasibility tests on a CIDI engine.

• Phase II:

- Design low cost integrated sensor module suitable for mass production.

- Perform detailed characterization testing to establish long-term accuracy, reliability, and life.

- Perform demonstration testing using test stand engine and on-road vehicles in conjunction with 

engine manufacturers.

Approach

• Phase I:

- Develop specifications for sensor operating requirements in consultation with industry partners. 

- Modify existing designs of MEMS thin film chemical, pressure and flow sensors to meet sensor 

system requirements.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

25

- Modify existing smart sensor control electronics to produce real-time data and linearization of 

analog signals that are proportional to mass flow rate, oxygen, hydrocarbon, and carbon dioxide 

concentrations.

- Fabricate and checkout two prototype sensors.

- Evaluate accuracy and time response for a practical sensor.

- Perform demonstration tests with a test stand mounted diesel engine.

Accomplishments

• Baseline set of sensor requirements developed to guide design of sensor.

• MEMS based device fabrication initiated.

Future Directions

• Integration of technology with engine control systems with engine OEMs.

• Demonstration of low cost production of sensor.

Introduction

The purpose of this project is to address the 

critical need for CIDI engine on-board sensor 

technology to enable emissions reductions and 

efficiency improvements. After one hundred years of 

combustion engine development, exact knowledge of 

the air/fuel ratio of the combustion in each cylinder 

on each cycle remains an elusive goal [1]. While 

there are numerous diagnostic measurement 

techniques such as optical absorption, light scattering 

and mass spectroscopy which are very powerful tools 

for engine development and laboratory testing, they 

are inherently too costly and complex to be practical 

engine sensors. MEMS (Micro-Electro-Mechanical 

Systems) technology holds the potential for 

addressing this need with a low cost solution that can 

be practical to implement in mass produced engines. 

Low cost MEMS-based pressure sensors are widely 

used in the automotive industry. The thin film 

MEMS sensors to be investigated in this program are 

fabricated by the same types of processes used for 

mass production of low cost integrated circuits.

Emissions reductions is a major challenge for 

CIDI engines. Electronic injection, exhaust gas 

recirculation (EGR), and cleaner fuels have all had 

an impact on reducing emissions. Further 

improvement in engine operation and reduction of 

emissions can be achieved by improved knowledge 

of the mass flow rate of air into the engine and 

preferably each cylinder. Of particular interest is the 

calculation of instantaneous and cycle accumulated 

mass flow to each cylinder, as well as the 

concentration of oxygen, hydrocarbons, and carbon 

dioxide which may be present in engines using EGR 

to reduce emissions.

Approach

In Phase I, two integrated prototype units are 

being fabricated, and demonstration testing will be 

Figure 1. Smart Engine Intake Sensor Uses Advanced 

Solid-State MEMS Sensors and Compact 

Micro-Electronics for Simultaneous 

Measurement of Oxygen Concentration, 

Hydrocarbons, and Real-Time Calculation of 

Instantaneous and Cycle Accumulated Mass 

Flow.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

26

performed to define the capability of the system and 

sensors. The major components of the proposed 

Smart Engine Air Intake Sensor are shown in Figure 

1. The system consists of two principal elements: (1) 

integrated micro-electronic sensor elements for gases 

of interest, velocity, pressure and temperature, and 

(2) miniature application specific integrated circuit 

(ASIC) based electronics to provide signal 

conditioning, signal processing, and communications 

functions. We envision this system to be integrated 

into a small (0.5" diameter x 2") package that would 

be suitable for integration into the intake manifold or 

at each intake valve on an engine. Phase II of the 

program will address the packaging and 

miniaturization issues in detail in Phase II of the 

program.

The first major task will be to select and adapt 

existing CWRU/MEI sensor designs for the oxygen, 

hydrocarbon, CO2, thermal flow, and pressure 

sensors. A set of system requirements will be 

developed through consultation with DOE and 

engine manufacturers. Sensor time response and 

sensitivity will be adjusted for expected detection 

ranges. These sensors will be used in die form 

(typically 3 mm x 3 mm and designed into a single 

integrated sensor head that can be mounted flush 

with a wall). The sensor control electronics will be 

adapted from existing designs for the prototype in 

Phase I and will be optimized in Phase II.

The second major task will be the fabrication and 

integration of the sensors and the electronics into two 

working prototypes. Firmware developed for the 

operation of the sensor system will be validated, and 

tests will be conducted to calibrate the sensors and to 

evaluate and compensate for cross sensitivities. 

Sensor stability, repeatability, and thermal cycle 

behavior will be tested.

The third major task will be to perform testing of 

the system using dynamometer mounted engines at 

U.C. Berkeley. Tests will be conducted using sixcylinder DI compression ignition engines capable of 

EGR and single cylinder test engines. The single 

cylinder engines will be configured for homogeneous 

charge combustion and with high levels of EGR. We 

will use the engine tests to validate bench-testing 

results and to develop a preliminary data package 

that we intend to share with engine manufacturers. 

We plan to have one or more engine manufacturers 

participate in Phase II of the project.

Conclusions

A set of baseline requirements (Table 1) have 

been developed for the sensor which serve as the 

design requirements for the Phase 1. Application of 

these requirements to the known operational 

characteristics of the sensors under investigation 

indicated that the needed mass flow sensor can be 

achieved.

List of References

1. Sensor Needs and Requirements for Proton 

Exchange Membrane Fuel Cells Systems and 

Direct-Injection Engines, UCRL-ID-137767, Jan 

2000.

List of Acronyms

ASIC Application Specific Integrated 

Circuit

CIDI Compression Ignition, Direct 

Injection

CWRU Case Western Reserve University

EGR Exhaust Gas Recirculation

MEI Makel Engineering, Inc.

MEMS Micro-Electro-Mechanical Systems

OEM Original Equipment Manufacturer

UCB University of California, Berkeley

Parameter Specification

Oxygen Range 25 ppm-25% @ STP

Hydrocarbon Range 50 ppm -1% @ STP

Carbon Dioxide 50 ppm to 10% @ STP

Temperature -40o

C to 125oC

Pressure 10 to 25 psia

Velocity 0 to 20 m/sec

Sensor Response Time Less than 100 microseconds

Operating Pressure 1.5 atm to 1 torr

Sensor Head Size 1.5 cm diameter, flush mount

Power Consumption < 3 watts per sensor module

Power to Sensor 12 or 24 VDC, 300 mA max

Data Communications Digital Protocol/analog output

Table 1. Preliminary Specifications for the Smart Engine 

Air Intake Sensor
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

27

C. Advanced CIDI Engine Diesel Combustion R&D

Paul Miles

Sandia National Laboratories

P.O. Box 969, MS9053

Livermore, CA 94551

(925) 294-1512, fax: (925) 294-1004, e-mail: pcmiles@sandia.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

Contractor: Sandia National Laboratories, Livermore, CA

Contract Number DE-AC04-94AL85000

Subcontractors: University of Wisconsin Engine Research Center (UW ERC), Madison, WI; Wayne 

State University (WSU), Detroit, MI

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

3. Fundamental Combustion R&D

Objective

• To provide the physical understanding of in-cylinder combustion processes needed to meet the 

efficiency and emissions standards of the PNGV vehicle.

Approach

• Obtain measurements which clarify the fundamental in-cylinder physical processes important to CIDI 

diesel combustion through use of optical diagnostic techniques in a geometrically-realistic optical 

engine.

• Correlate in-cylinder processes observed in the optical engine to tailpipe emissions and traditional, 

pressure-based performance analysis in a conventional single-cylinder test engine with geometry and 

operating conditions as close as possible to the optical engine (WSU).

• Incorporate fundamental physical processes into detailed computer models of engine combustion; 

validate the output of these models against traditional test engine emissions and performance (UWERC).

Accomplishments

• Investigated the influence of flow swirl on rate of heat release and spatial combustion characteristics, 

employing analysis of cylinder pressure data and imaging of natural luminosity. Established:

- The decrease of ignition delay with increasing swirl, with corresponding decreases in peak heat 

release and combustion noise.

- The invariance of ignition locations with flow swirl.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

28

- The increased rates of mixing-controlled combustion achieved with higher swirl.

- The greater squish volume combustion activity which occurs with higher swirl.

- The zones of late cycle-oxidation of soot and unburned hydrocarbons (UHC), including 

unexpected asymmetries.

• Investigated the combustion of cetane-degraded fuels (ethanol/D2) blends on the combustion process. 

Established:

- The invariance of ignition location with ignition delay (cetane number).

- The role of combustion gas expansion during the premixed burn in enhancing turbulence and rates 

of heat release in the mixing-limited combustion.

• Investigated the effects of injector nozzle type and opening pressure on the combustion process. 

Established:

- The minor influence of nozzle style (VCO vs. minisac) on combustion phasing and spatial 

characteristics.

- The dependency of ignition location and squish volume combustion activity on nozzle opening 

pressure.

• Improved data acquisition capability and experimental controls, and installed laser systems required 

for future work.

• Completed characterization of combustion performance at three key speed/load conditions and 

comparison with optical engine (WSU).

• Conducted tests of emissions (smoke, NOx, UHC, CO) and ISFC at three key speed/load conditions, 

for several EGR levels and fuel injection pressures (WSU). Compared engine emissions and 

performance with state-of-the-art 4-valve CIDI engines.

• Enhanced traditional engine laboratory capabilities, adding PM mass and noise measurement 

capability (WSU).

• Performed full-cycle simulations for both traditional and optical engines at three key points, Rs=1.5 

(UW ERC). Compared pressure-derived results with experimental data.

• Performed full-cycle simulations at 2000 rpm/5.0 bar IMEP load point for variable swirl ratios. 

Compared and contrasted computed and experimental results. Established:

- The "bluff-body" like character of the fuel sprays, and the importance of recirculation zones in 

establishing the ignition location.

- The increased fuel in the squish volume at higher swirl ratios, corresponding to the experimentally 

observed increased combustion activity.

- The role of the velocity field set-up by the swirl/squish interaction in positioning the fuel near the 

entrance to the squish volume and the role of the gas expansion in forcing the unburned fuel into 

the squish volume.

- The need for further code development/refinement to accurately predict the locations of late-cycle 

soot oxidation.

• Identified the inability of traditional (shell) ignition sub-models to accurately predict ignition delay 

and location under idle conditions in the CIDI engine. Developed and commenced testing of new 

model valid for high EGR levels.

• Continued development and verification of computationally efficient spray models.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

29

Future Directions

• Provide more detailed, quantitative data to clarify the effects of the in-cylinder velocity field 

(including turbulence levels) on the fuel distribution, mixing rates, and late-cycle burnout. Continue 

with application of laser-based techniques to investigate the influence of swirl on the spatial 

distributions of particulate and of liquid phase fuel. Compare results on a detailed level with model 

predictions.

• Optimize combustion system through continued traditional engine testing. Investigate ability of codes 

to predict the trends of the emissions and performance testing as the optimization proceeds. 

Commence with development of a comprehensive data base detailing the trade-offs in emissions and 

performance as injection pressure, swirl level, and EGR are varied.

• Perform computer simulations to compare with traditional test engine emissions results and incylinder measurements. Further refine and test computational sub-models for ignition and sprays

Introduction

CIDI engines intended for passenger car or lightduty truck applications differ from heavy-duty diesel 

engines in two important aspects. First, they feature 

swirl-supported combustion systems. In-cylinder 

flow swirl influences the entire combustion processfrom the initial preparation of a combustible mixture 

to the final burnout of the soot and unburned 

hydrocarbons. Second, the interaction of the 

combustion chamber walls with the in-cylinder 

flows, sprays, and combustion becomes an important 

factor in determining the evolution of the combustion 

process. To develop fuel efficient engines in this size 

class, a sound understanding of the physics of the 

swirl-supported combustion and of the wall 

interactions is required. Moreover, computational 

models must capture the relevant physical processes 

if they are to produce accurate results and serve as 

reliable design tools.

Approach

In this research project, a three-pronged 

approach is taken toward obtaining the required 

physical understanding and reliable modeling 

capabilities: detailed measurements of the flow and 

combustion processes are made in an opticallyaccessible laboratory test engine; emissions, 

performance and fuel consumption measurements 

are made in a traditional single-cylinder test engine; 

and computer simulations are performed and 

compared to the data obtained in the optical and 

traditional test engines. Natural synergies emerge 

among these three areas. For example, the 

comparison of the computed and the experimental 

results serves to establish the validity of the various 

sub-models in the codes, to verify the ability of the 

codes to accurately predict global parameters such as 

emissions, and to assist in the interpretation of the 

experimental data. Similarly, traditional test engine 

measurements serve to identify interesting operating 

parameter trade-offs that bear further investigation 

either numerically or experimentally in the optical 

engine.

Results

The optically-accessible CIDI diesel engine 

facility is depicted in Figure 1. This facility employs 

a slotted, extended piston assembly with a quartz 

combustion chamber that permits the progress of 

combustion to be visualized from below. In addition, 

Figure 1. Schematic view of the optical engine facility
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

30

the upper region of the cylinder liner is equipped 

with quartz windows that allow a lateral view of the 

combustion process to be obtained. This lateral view 

capability, in a configuration that maintains the 

faithful combustion chamber geometry, is a unique 

aspect of this facility. The engine bowl geometry, 

bore, and stroke are typical of state-of-the-art CIDI 

diesel engines for passenger car applications. 

Variable cylinder swirl levels can be achieved 

through throttling of one of the intake ports. The 

achievable swirl levels span the range employed by 

most DI diesel engines.

Analysis of pressure data and of images of 

natural combustion luminosity in the optical engine 

has been employed to study the effect of swirl on 

various aspects of the combustion process. Figure 2 

presents the effect of variable swirl on the apparent 

heat release rate. Note that increasing swirl can be 

seen to decrease the ignition delay, leading to lower 

peak heat release rates and consequently quieter 

operation. Images of early combustion 

chemiluminescence demonstrate that the ignition 

location remains the same for all three swirl ratios, as 

can be seen in Figure 3. Furthermore, computed 

ignition locations (also shown in Figure 3) can be 

seen to agree well with the measured locations. A 

more detailed examination of the computed velocity 

field has demonstrated that this invariance in ignition 

location is associated with flow recirculation and reentrainment zones behind the fuel spray.

As combustion progresses beyond the premixed 

burning period, a period of mixing-controlled 

combustion is entered in which little difference is 

seen in the heat release rate with swirl ratio. During 

this time, the mixing is likely dominated by the 

turbulence generated by the fuel injection process. As 

combustion proceeds, however, a clear increase in 

Figure 2. The effect of swirl on the apparent heat release 

rate. The envelope of repeatability of the data 

is illustrated for a swirl ratio Rs of 2.5, which 

appears as a heavy line in Figure 2. Note that 

the differences observed with variable swirl are 

generally greater than the repeatability of the 

data. Figure 3. A comparison of the experimental and the 

computed ignition locations for the three swirl 

ratios.

Figure 4. Images of luminosity obtained during the latter 

portion of the mixing-controlled combustion 

period.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

31

the rate of heat release with increased swirl ratio can 

be seen between about 7 and 16 crank angle degrees, 

during the latter part of the mixing controlled burn 

(see Figure 2). Images of combustion luminosity 

during this time period are shown in Figure 4. The 

notable differences in the spatial distribution of 

combustion luminosity are an increase of activity in 

the squish volume at the higher swirl ratios and a 

decrease in activity in the upper, central region of the 

bowl. Comparison with computed results indicates 

that the increased squish volume activity is due to the 

presence of a greater amount of fuel within the 

squish volume at higher Rs

, as is illustrated in Figure 

5. Fuel in the squish volume is undesirable, because 

heat losses in the squish volume may cause the flame 

to quench, leading to particulate and UHC emissions. 

More fuel enters the squish volume at higher swirl 

ratios due to differences in the mean velocity field 

caused by the swirl/squish interaction, as revealed by 

the computational results. Computations also 

indicate that the decreased activity in the upper 

central bowl regions is likely due to increased 

turbulence at higher swirl levels, leading to a more 

rapid burnout of fuel in those regions and less 

activity at the time shown in Figures 4 and 5.

Figure 6 presents the soot-NOx trade-off for 

several EGR rates and injection pressures at the 2000 

rpm, 5.0 bar IMEP load point. The behavior seen is 

typical of state-of-the-art CIDI engines, and shows 

the turn-up in particulate matter at about 5 gm NOx/

kg fuel that is considered the current lower bound of 

NOx emissions for CIDI engines. The smoke 

numbers seen here, of between 1 and 3 Bosch Smoke 

Units (BSU), are somewhat high, as best-in-class 

engines will typically exhibit smoke levels of about 

0.5 BSU at these NOx levels and an 800 bar injection 

pressure. The higher than expected smoke numbers 

are within the range of expected improvements as the 

details of the combustion system are optimized, and 

the ability of the computed results to follow the 

optimization process will provide a rigorous test of 

the current and future CIDI engine models.

Conclusions

Imaging of combustion luminosity and heat 

release analysis, combined with computational 

model predictions, has led to considerable insight 

into the effect of swirl on the combustion process in a 

CIDI engine typical of engines intended for 

passenger car applications. Swirl is found to decrease 

ignition delay as well as the peak rates of heat 

release, although the spatial character of the ignition 

process is not changed. In addition, increased swirl is 

found to increase the rate of combustion during the 

latter part of the mixing controlled burn, and to 

increased squish volume activity. Computations 

assist in determining the underlying cause behind 

these observations.

Figure 5. Computed fuel distributions, showing the 

increased fuel found in the squish volume at 

the higher swirl ratios.

Figure 6. The soot-NOx trade-off determined in the 

traditional test engine, for fixed location of 

peak pressure as EGR and injection pressure 

are varied.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

32

Testing in a traditional test engine has 

demonstrated that the test engine geometry is capable 

of achieving best-in-class emission performance with 

additional combustion system optimization. 

Performing this optimization provides an opportunity 

to test the ability of the computational models to 

accurately predict trends in CIDI engine performance 

and emissions.

List of Publications

1. Miles, P.C. "The Influence of Swirl on HSDI 

Diesel Combustion at Moderate Speed and 

Load," Spring SAE Fuels and Lubricants 

Meeting, 19-20 June 2000; SAE Paper No. 2000-

01-1829.

2. Miles, P.C. " Combustion of an Ethanol/Diesel 

Fuel Blend in an HSDI Diesel Engine," To be 

presented at THIESEL 2000, 

Thermofluidynamic processes in Diesel Engines, 

13-15 Sept. 2000.

3. Han, J.S., Wang, T.C., Lai, M.-C., Henein, N.A., 

Miles, P.C. and Harrington, D.L. "Dynamics of 

Multiple Injection Fuel Sprays in a Small-Bore 

HSDI Diesel Engine," SAE Int’l. Congress, 6-9 

March 2000; SAE Paper No. 2000-01-1253.

4. Henein, N.A., Lai, M.-C., Wang, T.C., and Miles, 

P.C. "Combustion and Emission Characteristics 

of a Single-Cylinder HSDI Diesel Engine," 

Spring Technical Conference of the Central 

States Combustion Institute, 16-18 April 2000.

5. Tennison, P.J. and Reitz, R.D. "The Effects of 

Common Rail Injection Parameters on Emissions 

and Performance of a HSDI Diesel Engine," 

ASME Fall IC Engines Conference, 16-20 Oct. 

2000.

6. Bianchi, G.M., Michelassi, V., and Reitz, R.D. 

"Modeling the Isotropic Dissipation in Engine 

Flows by Using the Linear k-ε Model," ASME 

Fall IC Engines Conference, 16-20 Oct. 2000.

7. Kong, S.-C., Senecal, P.K., and Reitz, R.D. 

"Developments in Spray Modeling in Diesel and 

Direct-Injection Gasoline Engines," Oil & Gas 

Science and Technology - Rev. de l’IFP, Vol. 54, 

No. 2, pp. 197-204, 1999.

List of Presentations

1. Miles, P.C. "Combustion Performance and 

Natural Luminosity at Key Point III: Effect of 

Varying Swirl"; Richards, K. "Motoring and 

Combustion Simulation of the Optical and Metal 

HSDI Engines"; Henein, N.A. and Lai, M.-C. 

"CIDI Metal Engine Instrumentation and 

Testing"; Diesel Combustion CRADA Meeting, 

12-13 Oct. 1999, USCAR, Southfield, MI.

2. Miles, P.C. "Combustion Performance and 

Chemiluminescence Imaging: A Comparison of 

Neat D2 with an Ethanol/D2 Blend"; Henein, 

N.A. "Effect of Injection Pressure on the TradeOffs in the Metal CIDI"; Richards, K. "Progress 

on HSDI Diesel Engine Modeling and 

Assessment of Spray Models"; Diesel 

Combustion CRADA Meeting, 20-21 Jan. 2000, 

Sandia Natl. Labs., Livermore, CA.

3. Richards, K. "Progress on HSDI Diesel Engine 

Modeling and Assessment of Spray Models"; 

Henein, N.A. "Effect of Injection Pressure, EGR 

and Swirl on the Emissions in the CIDI Metal 

Engine"; Paul Miles, P.C. "Progress and Current 

Status in the HSDI Combustion Partnership"; 

Diesel Combustion CRADA Meeting, 31 May - 

1 June 2000, USCAR, Southfield, MI.

4. Miles, P.C., Henein, N.A., Lai, M.-C., Reitz, 

R.D., and Richards, K. "CIDI Diesel 

Combustion: Progress June 1999 - Present," 

DOE OATT Annual Review, 22-24 May, 

Argonne Natl. Lab., Argonne, IL.

List of Acronyms

BSU Bosch Smoke Unit

CAD Crank Angle Degree

CIDI Compression Ignition Direct 

Injection

D2 Number 2 Diesel Fuel

DI Direct Injection

EGR Exhaust Gas Recirculation

HSDI High-Speed Direct-Injection

IMEP Indicated Mean Effective Pressure

ISFC Indicated Specific Fuel 

Consumption

PNGV Partnership for a New Generation 

Vehicle

TDC Top Dead Center

UHC Unburned Hydrocarbon
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

33

UW-ERC University of Wisconsin Engine 

Research Center

VCO Valve Covered Orifice

WSU Wayne State University 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

34

D. Extending Exhaust Gas Recirculation Limits in CIDI Engines

Johney Green, Jr. (primary contact) and Stuart Daw

Oak Ridge National Laboratory

P.O. Box 2009

Oak Ridge, TN 37831-8088

(423) 574-0373, fax (423) 574-2102, e-mail: greenjbjr@ornl.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

ORNL Technical Advisor: Ralph McGill

(423) 574-4077, fax (423) 574-2102, e-mail: mcgillrn@ornl.gov

CRADA Partner: Ford Motor Company, Dearborn, Michigan

CRADA No. ORNL 95-0337

Ford Investigators: John Hoard (primary contact), Lee Feldkamp, Tony Davis, and Frank Connolly

(313) 594-1316, fax: (313) 594-2923, e-mail: jhoard@ford.com

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

Tasks

2. Sensors and Controls

4e. R&D on NOx Reducing Technologies

Objective

• Develop options for extending the practical EGR limit to further reduce engine-out NOx from CIDI 

engines.

Approach

• Identify correlations between EGR operating and system parameters and combustion emissions.

• Evaluate correlations between existing engine sensors and pressure/emissions signals to develop a 

virtual HC/PM/NOx sensor concept.

• Develop a low-order dynamic model that captures the relationship between EGR, combustion, and 

emissions.

• Exploit information from the virtual sensor and low-order model to develop a dynamic EGR control 

concept.

Accomplishments

• Conducted EGR experiments on the 1.2-L, 4-cylinder Ford DIATA (Direct Injection, Aluminum, 

Through-bolt Assembly) diesel engine.

• Conducted EGR experiments at ORNL with a 1.9-L, 4-cylinder VW TDI engine outfitted with a 

LBNL diesel particulate scatterometer to measure PM density, a Cambustion fast-FID analyzer to 

measure cycle-resolved HC emissions, a Tapered Element Oscillating Microbalance (TEOM) to 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

35

measure PM mass, a Scanning Mobility Particle Sizer (SMPS) to measure PM size, and Kistler incylinder pressure transducers to obtain combustion parameters.

• Discovered correlations between emissions and combustion parameters using data from VW TDI 

engine.

• Observed similar correlations in emissions and combustion data from Ford DIATA engine.

• Developed concept for a virtual sensor and control strategy that can be used to extend EGR limits in 

CIDI engines.

Future Directions

• Demonstrate proof-of-principle for virtual emissions sensor by correlating in-cylinder pressure 

measurements with PM, HC, and NOx emissions at high EGR on multiple CIDI engines.

• Demonstrate feasibility of virtual sensors by developing correlation between existing sensors (e.g., 

crankshaft acceleration) and in-cylinder pressure measurements.

• Demonstrate usefulness of a low-order dynamic model for predicting the relationship between EGR, 

combustion, and emissions.

• Demonstrate active feedback control for stabilizing engine operation at high EGR, thereby reducing 

NOx by as much as 50%.

Introduction

This activity builds on an earlier collaboration 

between ORNL and Ford under a pre-existing 

CRADA (ORNL 95-0337). Under the original 

CRADA, the principal objective was to understand 

the fundamental causes of combustion instability in 

spark-ignition engines operating at lean air-fuel 

ratios. The results of this earlier activity 

demonstrated that such combustion instabilities are 

dominated by the effects of residual gas remaining in 

each cylinder from one cycle to the next. A very 

simple, low-order model was developed that 

explained the observed combustion instability as a 

noisy nonlinear dynamical process. The model 

concept led to development of a real-time control 

strategy that could be employed to significantly 

reduce cyclic variations in real engines using existing 

sensors and engine control systems. Figure 1 

illustrates the effectiveness of this control in a 

commercial engine.

With funding from OAAT, the CRADA has been 

modified to focus more on EGR and CIDI engines. 

The modified CRADA now includes engine 

experiments and analysis at both Ford and ORNL.

Activities at Ford

The strong correlation between hydrocarbon 

(HC) emissions and location of peak cylinder 

pressure in the DIATA engine is illustrated in Figure 

2. We observe that HC emissions correlate with 

EGR rate, and these in turn correlate with the 

combustion process (as reflected in the location of 

Figure 1. Experimental example of reduced cylinder-tocylinder combustion instability achieved on 

commercial spark-ignition engine with cycleresolved feedback control. Deviations from 

dashed line in upper figures and peaks in lower 

figures reflect high instability.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

36

the peak cylinder pressure or LPP). Note that at 

higher EGR levels, very small changes in EGR rate 

have a highly nonlinear effect.

Activities at ORNL

ORNL experiments with the 1.9-L VW TDI 

engine were conducted in November of 1999. The 

purpose of these experiments was to confirm and 

extend the correlations observed in the Ford DIATA 

experiments. The VW engine was equipped to 

measure cycle-resolved PM density, cycle-resolved 

HC emissions, time-averaged HC, NOx and CO 

emissions, PM mass, PM size, and cylinder pressure 

from multiple cylinders.

Figure 3 shows the nonlinear behavior of HC and 

PM emissions at high EGR levels. If the engine 

could be operated at an EGR rate of 40% instead of 

25%, there would be a 60% reduction in NOx

emissions. The correlation between PM particle size 

and EGR rate is shown in Figure 4. The number of 

larger particles increases while the number of smaller 

particles decreases at high EGR rates. Cycleresolved particulate density measurements reveal a 

different level of PM generation for each cylinder 

(Figure 5). The cylinder-to-cylinder variability most 

likely results from the mal-distribution of EGR to the 

cylinders. Figure 6 shows that HC emissions 

increase in cycle-to-cycle variability as EGR rate 

increases.

We believe that the mechanism behind the cycleto-cycle variations in HC emissions is also 

responsible for the cylinder-to-cylinder 

communication depicted in Figure 7. A similar 

Figure 2. Example correlation between combustion and 

emissions for the DIATA engine with 

increasing levels of EGR. Combustion delay is 

characterized by shifts in location of the peak 

cylinder pressure. Note similar trends for HC 

emissions and combustion delay with EGR.

Figure 3. Sharp transition in HC and PM emissions for 

VW engines as EGR is increased. The solid 

arrows indicate typical existing operating 

limits set to prevent occasional excursions into 

high HC and PM. The dotted arrows indicate 

potential operating points if the engine can be 

stabilized by high-speed feedback control, 

allowing substantial NOx reduction with only 

slight HC and PM increases.

Figure 4. Example correlation between particle size and 

EGR rate. It appears that EGR particles 

reintroduced into the combustion chamber act 

as nuclei for new particles and agglomerate to 

form larger particles.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

37

synchronization between cylinder pairs was also 

observed and eliminated in the Ford spark-ignition 

engine control experiments (Figure 1). The 

correlations between emissions and EGR rate shown 

in Figures 2 and 8 lead us to believe that relationship 

can be exploited and used to develop a virtual sensor. 

The sensor would utilize existing engine sensors 

(e.g., crankshaft acceleration) and relate them to 

emissions at a given EGR rate. A low-order model 

would also be developed to gain a better 

understanding of the mechanism behind these 

correlations. The information obtained from these 

tools would serve as the basis for advanced dynamic 

EGR control.

Summary

Experimental work during FY2000 focused on 

the development of high-time-resolution 

measurements of particulate matter, hydrocarbons, 

and nitrogen oxides. These emissions monitoring 

capabilities have significantly improved our ability 

to resolve the impact of cylinder-to-cylinder 

imbalances, EGR mal-distribution, and cycle-tocycle combustion variations on the transient 

emissions spikes associated with high EGR rates. 

Recent experimental results have revealed a possible 

mechanism for the growth of PM particle size at high 

EGR rates and strong correlations between incylinder pressure measurements and time-average 

PM/HC/NOx emissions. The experimental results 

also indicate that diesel combustion instability 

patterns reflect cylinder-to-cylinder interactions that 

have features similar to those in spark-ignited 

engines at high EGR, although the combustion 

details are significantly different. These results 

Figure 5. Example cycle-resolved PM density 

measurement. Cylinder-to-cylinder differences 

in PM generation are clearly visible.

Figure 6. The cycle-to-cycle variability of HC emissions 

increases as EGR rate increases.

Figure 7. Synchronization (cross-talk) between cylinders 

F-0 and F-1 in the VW engine is similar to the 

synchronization observed in the uncontrolled 

spark-ignition engine experiment (Figure 1). 

Such interaction contribute to high EGR 

instability.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

38

continue to confirm the importance of experimental 

characterization and modeling of EGR and fueling 

systems for developing strategies to maximize NOx

reduction potential. 

The objectives in FY2001 are to demonstrate a 

virtual sensor concept for predicting HC, PM, and 

NOx emissions and to demonstrate a low-order 

dynamic EGR/emissions model for predicting and 

controlling combustion instabilities near the EGR 

limit. The virtual sensor approach is based upon 

exploiting the relationships between existing vehicle 

sensor outputs and emissions. The low-order 

dynamic EGR/emissions model will exploit the 

relationship between combustion instability, 

emissions, and the propagation of combustion 

instability effects through the engine/EGR system. 

This model is expected to serve as the basis for 

demonstrating advanced dynamic EGR control.

List of Publications

1. Daw C.S., Kennel M.B., Finney C.E.A., 

Connolly F.T. (1998). "Observing and modeling 

nonlinear dynamics in an internal combustion 

engine", Physical Review E 57:3, 2811-2819. 

2. Daw C.S., Green J.B. Jr., Wagner R.M., Finney 

C.E.A., Connolly F.T. (2000). Synchronization 

of combustion variations in a multi-cylinder 

spark ignition engine. Twenty-Eighth 

International Combustion Symposium 

(Edinburgh SCOTLAND; 2000 July 30 - August 

04).

3. Finney C.E.A., Green J.B. Jr., Daw C.S. (1998). 

"Symbolic time-series analysis of engine 

combustion measurements", SAE Paper No. 

980624. 

4. Green J.B. Jr., Daw C.S., Armfield J.S., Finney 

C.E.A., Wagner R.M., Drallmeier J.A., Kennel 

M.B., Durbetaki P. (1999). "Time irreversibility 

and comparison of cyclic-variability models", 

SAE Paper No. 1999-01-0221. 

5. Wagner R.M., Drallmeier J.A., Daw C.S. (1998). 

"Nonlinear cycle dynamics in lean spark ignition 

combustion", 27th International Symposium on 

Combustion (Boulder, Colorado USA; 1998 

August 2-7). 

6. Wagner R.M., Drallmeier J.A., Daw C.S. (1998). 

"Prior-cycle effects in lean spark ignition 

combustion: fuel/air charge considerations", 

SAE Paper No. 981047.

7. Wagner R.M., Green J.B. Jr., Storey J.M., Daw 

C.S. (2000). Extending exhaust gas recirculation 

limits in diesel engines. 2000 Annual Conference 

and Exposition of the Air & Waste Management 

Association (Salt Lake City, Utah USA; 2000 

June 18 - 22), Paper 643. 

List of Acronyms

CIDI Compression-ignition direct 

injection

CRADA Cooperative Research and 

Development Agreement

DIATA Direct Injection, Aluminum, 

Through-bolt Assembly

EGR Exhaust Gas Recirculation

HC Hydrocarbons

LBNL Lawrence Berkeley National 

Laboratory

LPP Location of Peak Pressure

NOx Oxides of Nitrogen

Figure 8. VW experiments reveal the same correlation 

observed in DIATA experiments (Figure 2) 

between peak pressure location and emissions. 

The correlations between combustion 

measurements (e.g. crankshaft acceleration) 

and emissions will be employed to develop a 

virtual sensor concept.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

39

OAAT Office of Advanced Automotive 

Technologies (U.S. Department of 

Energy)

PM Particulate Matter

SMPS Scanning Mobility Particle Sizer

TDI Turbocharged Direct Injection

TEOM Tapered Element Oscillating 

Microbalance

VW Volkswagen
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

40

E. Measuring the Cylinder-to-Cylinder Distribution of Recirculated Exhaust Gas 

during Transient Operation of a CIDI Engine

R. M. Green

Sandia National Laboratories

7011 East Avenue, MS 9053

Livermore, CA 94550

(925) 294-2568, fax: (925)294-1004, e-mail: rmgree@sandia.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

Contractor: Sandia National Laboratories, Livermore, CA

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

Tasks

2a. Advanced Sensors and Controls

4e. R&D on NOx Reducing Technologies

Objectives

• Develop a non-intrusive, optical diagnostic to measure the cylinder-to-cylinder EGR distribution in 

production diesel engines during both steady-state and transient operation.

• Make the technology available to industry by performing measurements on development and/or 

prototype engines in industrial test cells.

Rationale

• Contemporary diesel engine designs are now using increasingly large amounts of EGR to control NOx

emissions.

• Poor cylinder-to-cylinder distribution of EGR can lead to serious performance and/or emission 

problems:

- non-uniform combustion performance; and

- excessive PM emissions; or

- excessive NOx emissions.

• Engine-operation transients may seriously aggravate the problems.

Approach

• Apply the diagnostic to a production engine minimizing perturbations to basic engine geometry.

• Use IR absorption spectroscopy to measure the CO2 concentration in the flow entering the intake port 

of each cylinder.

• Set up data acquisition to allow measurements during both steady and transient operation.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

41

• Acquire the data in a manner that is both crank-angle and cycle-sequence resolved as well as ensemble 

averaged.

Accomplishments

• A Volkswagen 1.9L TDI engine is set up and is operational in the laboratory, with the capability of 

computer control under either steady conditions or speed/load/EGR transients.

• The optical access to the intake ports is fabricated, installed and operational.

• The infrared, diode-laser based CO2-absorption diagnostic is operating in the engine. Data acquisition 

can be performed during both steady operation and transients, yielding the required crankangle- and 

cycle-resolved, ensemble-averaged data.

• Various optical and mechanical problems have been identified, analyzed and successfully resolved.

• Refined steady-state and transient measurements have successfully demonstrated the credibility and 

capability of the diagnostic.

Future Directions

• Issues related to system ’portability’ are being addressed.

• We must refine the philosophy of the optical access to be in a position to perform measurements in 

engines with intake configurations different from that of the Volkswagen TDI.

• We are working with industry to organize cooperative working arrangements that involve using our 

diagnostic to perform measurements on development and prototype engines.

Introduction

The new generation of small-bore CIDI engines 

being developed for automotive applications is 

expected to use large amounts of EGR to minimize 

the engine-out emission of NOx. Large quantities of 

EGR could result in mixing problems in the intake 

manifold, and ultimately, a poor cylinder-to-cylinder 

distribution of EGR. The problem is most likely 

exacerbated during transients in the operation of the 

engine. In order to make an accurate assessment of 

the cylinder-to-cylinder distribution of EGR during 

an engine transient, we have devised a non-intrusive, 

optical diagnostic technique which will allow the 

measurement of the cylinder-to-cylinder EGR 

distribution during engine transients.

Diagnostic

The diagnostic we are developing is based on 

laser absorption spectroscopy of the CO2 molecule, a 

primary component of the recirculated exhaust. An 

infrared diode laser provides light that is tuned to an 

absorption transition of CO2. The output wavelength 

Figure 1. The spacer plate located between the cylinder 

head and the manifolds contains windows, 

bounding the intake flow, which define the 

optical path. The fluoride-glass fibers carry the 

laser light from the laser to the engine where it 

passes through the intake flow, then back to the 

In-Sb detector.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

42

of the light is modulated so the absorption transition 

is continuously wavelength-scanned by the laser. 

Because of the extremely narrow output bandwidth 

of this laser, we can directly measure the absorptionline profile which is a function of the particular 

species, the concentration of that species, as well as 

the gas temperature and pressure. We analyze the 

experimentally measured absorption-line profiles by 

performing a non-linear, least squares fit of a 

theoretical Voigt profile of the absorption spectrum 

to the experimental profile. The results of this data 

fitting procedure are used to determine the average 

concentration of CO2 in the optical path of the laser.

Optical access to the engine is accomplished 

using a spacer plate between the intake and exhaust 

manifolds and the cylinder head. The spacer has 

been designed with windows that provide an optical 

path through the intake flow entering each port from 

the intake manifold. This configuration is illustrated 

in Figure 1. The laser light is transmitted through 

optical fibers to the engine where it is directed 

through the windows in the spacer plate - passing 

through the gas entering the intake port. It is then 

collected in another fiber, which transmits it to a LNcooled, In-Sb detector.

Steady Operation Results

The data in Figure 2 illustrate the temporally 

resolved, EGR-concentration variation during the 

intake stroke and how this variation behaves from 

cylinder to cylinder. Furthermore, they demonstrate 

that the concentration of EGR in the intake flow can 

vary considerably during the intake stroke and the 

temporal history of the variation is cylinder 

dependent. A striking feature of these results is the 

strong similarity between the CO2 concentration 

profiles for cylinders 1 and 4, and between those for 

cylinders 2 and 3. In addition, it is important to 

notice the striking difference in the profiles of 

cylinders 1 and 4 from those of cylinders 2 and 3. 

These observations are a consequence of the 

symmetry of the intake manifold where cylinders 1 

and 4 are at either end, and cylinders 2 and 3 are 

equally spaced about the mid-plane. These results 

dramatically demonstrate that even when operating 

Figure 2. The temporal history, during the intake stroke, 

of the CO2 concentration within the intake 

charge. The engine was run at the steady 

conditions of 1500 rpm and light load.

Figure 3. Results of the low temporal resolution transient 

measurements for cylinders 1 and 2. Each data 

point represents the average CO2 concentration 

during the intake stroke of a particular cycle of 

the sequence.

Figure 4. High temporal resolution measurements during 

transient engine operation. The data illustrated 

correspond to the first seven cycles following 

rapid closure of the EGR valve.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

43

at steady conditions, the engine’s internal EGR 

system can produce large temporal variations in the 

EGR concentration in the flow of fresh charge during 

the intake stroke.

Transient Operation Results

The data presented in this section demonstrate 

EGR-concentration measurements during an EGR 

transient. The EGR transient we used occurs within 

a sequence of 210 engine cycles during which no 

other engine parameter is changed. At the beginning 

of cycle 1 of the sequence, the EGR valve is rapidly 

closed by a solenoid-driven actuator, and during the 

first 105 cycles, the EGR valve remains closed. 

Then at the beginning of cycle 106, the EGR valve is 

rapidly opened and remains open during the last 105 

cycles. This sequence of cycles was repeated until 

sufficient data were collected for ensemble 

averaging. The data-acquisition system allowed us 

to resolve the data on both a crankangle-resolved 

basis and on a cycle-resolved basis.

 Figure 3 illustrates the transient measurements 

for a low temporal resolution, wherein the data are 

temporally averaged over the full 180 crank angle 

degrees (CAD) of the intake stroke. Figure 3 shows 

the cycle-history of the CO2 concentration in the 

intake flow as a function of the cycle number during 

the sequence for cylinders 1 and 2. These results 

indicate that a rapid closing of the EGR valve leads 

to complete purging of EGR from the intake flow 

within 6 to 8 engine cycles following the valve 

closure. However, following a rapid opening of the 

valve, it takes nearly 14 engine cycles to reach only 

90% of the steady-state EGR concentration. 

Furthermore, it appears to take nearly 100 additional 

cycles to achieve the last 10% and reach the steady 

value. Also, following a rapid EGR valve closure, 

the quantity of EGR in the intake flow into cylinder 2 

drops measurably faster than the quantity in the flow 

into cylinder 1. On the other hand, following a rapid 

opening of the EGR valve, the data indicate that there 

does not appear to be any measurable cylinder-tocylinder maldistribution of EGR in the intake flow.

 In Figures 4 and 5, we show the nature of the 

high temporal resolution, crankangle-binned data 

obtained during the engine transient. For these 

measurements, we used 10 crankangle bins during 

the intake stroke resulting in an 18 CAD temporal 

resolution. Figure 4 illustrates the temporal history 

of the CO2 concentration during the first seven cycles 

following the rapid closing of the EGR valve; while 

Figure 5 contains a similar set of results for the first 

ten cycles following the rapid opening of the EGR 

valve.

Summary

As a result of this project, we have developed an 

optical diagnostic that is capable of accurately 

measuring the cylinder-to-cylinder EGR distribution 

in a production engine, under both steady and 

transient operating conditions. This diagnostic is 

capable of a very low detection limit along with high 

precision. The data acquired can be both crankangleresolved and cycle-resolved during a sequence of 

cycles that define a transient in the engine operation. 

We are currently trying to establish collaborative 

arrangements with industry. In this regard, we are 

pursuing cooperative agreements with engine 

manufacturers wherein we will perform 

measurements using our IR absorption diagnostic on 

their development and/or prototype engines in their 

test cells.

List of Publications

1. R. M. Green, "Measuring the Cylinder-toCylinder EGR Distribution in the Intake of a 

Diesel Engine During Transient Operation," SAE 

Paper No. 00FL-573, to be presented at the 2000 

Figure 5. High temporal resolution measurements during 

transient engine operation. The data illustrated 

correspond to the first ten cycles following 

rapid opening of the EGR valve.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

44

SAE International Fuels and Lubricants Meeting 

and Exposition, Baltimore, MD, Oct. 2000.

List of Presentations

1. R. M. Green, "Investigation of the Cylinder-toCylinder Distribution of EGR in a DI Diesel 

Engine," DOE/Diesel Crosscut CRADA Review 

Meeting, USCAR, Detroit MI, October 12 & 13, 

1999. R. M. Green, "Status of EGR Distribution 

Measurements," DOE/SIDI Review Meeting, 

Sandia National Laboratories, Livermore CA, 

January 18, 2000.

2. R. M. Green, "Status of EGR Distribution 

Measurements," DOE/Diesel CRADA Review 

Meeting, Sandia National Laboratories, 

Livermore CA, January 20, 2000.

3. R. M. Green, "Measuring the Cylinder-toCylinder EGR Distribution in the Intake of a 

Diesel Engine During Transient Operation," 

CIDI Engine Combustion, Emission Control, and 

Fuels Merit Review & Peer Evaluation, Argonne 

National Laboratory, Chicago IL, May 22-24, 

2000.

List of Acronyms

CAD Crankangle Degrees

DI Direct Injection

EGR Exhaust Gas Recirculation

In-Sb Indium-Antimonide

IR Infrared

LN Liquid Nitrogen

PM Particulate Matter

TDI Turbocharged Direct Injection
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

45

F. Pressure Reactive Variable Compression Ratio Piston Development

John Brevick

Ford Motor Company

Beech Daly Technical Center, A-30 2001 S. Beech Daly

Dearborn Heights, Michigan 48125

(313) 845-0176, fax (313) 390-7375, e-mail: jbrevick@ford.com

DOE Program Manager: Ken Howden

(202) 586-3631, fax (202) 586-9811, e-mail: ken.howden@hq.doe.gov

Contractor: Ford Motor Company, Dearborn, Michigan

DOE Cooperative Agreement No. DE-FC02-99EE50576

Period of Performance: 09/30/1999 through 09/29/2001

Subcontractors: University of Michigan, Ann Arbor, Michigan; Federal-Mogul Corporation, Plymouth, Michigan

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

3a. Identification of Advanced Combustion Systems

Objectives

• Develop and demonstrate a pressure reactive piston for a spark-ignited (SI) engine.

• Develop and demonstrate a pressure reactive piston for a compression-ignited (CI) engine.

• Quantify engine efficiency and emission effects due to the pressure reactive piston.

Approach

• SI and CI engine simulation analysis.

• SI and CI single cylinder engine baseline testing.

• PRP spring design.

• PRP dynamic analysis.

• PRP design.

• PRP mechanical and thermal stress analysis.

• SI and CI PRP prototype manufacture.

• SI and CI PRP single cylinder engine testing

Accomplishments

• SI and CI baseline engine simulation analysis completed.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

46

• SI baseline engine simulation correlation to test data completed.

• SI engine simulation code modified to include the PRP degree of freedom.

• SI engine simulation efficiency predictions with the PRP completed.

• Baseline single cylinder engine dynamometer installation completed.

• PRP spring design complete.

• PRP dynamic analysis initiated.

• PRP design initiated.

• Baseline SI single cylinder engine testing initiated

Future Directions

• PRP design completion.

• PRP mechanical and thermal stress analysis.

• PRP prototype manufacture.

• Refine and iterate the dynamic model.

• Refine and iterate engine simulation models.

• SI and CI baseline single cylinder engine testing.

• SI and CI PRP single cylinder engine testing.

Introduction

The pressure reactive piston technology is based 

on a Ford Motor Company U.S. Patent #5,755,192 

(Variable Compression Ratio Piston) granted in 

1998. The PRP is a two-piece piston, separated by a 

spring system (see Figure 1). The patent was based 

on work in the late 1980s to early 1990s, which 

resulted in hardware being run in one cylinder of a 

multi-cylinder engine.

Many variable compression ratio piston designs 

have been patented and developed over the history of 

the internal combustion engine. Most of these 

technologies controlled the compression ratio 

throughout the engine cycle, and varied the 

compression ratio on demand (e.g., through 

controlling the oil volume in an upper versus lower 

chamber in the piston). The rate of compression ratio 

change may not be adequate at times where rapid 

load changes are demanded on the engine. A unique 

feature of PRP technology is that the upper piston 

reacts to cylinder pressure during the power stroke of 

the engine; during the rest of the engine cycle the 

upper piston remains in the high compression 

position.

The PRP operation strategy for a SI engine is to 

set the spring system preload to allow high 

Figure 1. Pressure Reactive Piston
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

47

compression (13:1) operation during partial engine 

load operation. During high engine load operation 

the spring system and piston geometry allows the 

effective compression ratio to decline (upper piston 

deflects relative to the piston pin) to prevent 

detonation or spark knock. Detonation is prevented 

because the peak cylinder pressure is limited by the 

deflection of the upper piston, controlled by the 

spring system. The expected result is higher engine 

efficiency at part load, which is typical operation for 

an automotive engine application. Reduced engine 

noise at high load is also anticipated.

The PRP operation strategy for a CI engine is to 

set the spring system preload to allow high 

compression (19:1) for start-up operation. Firing 

loads, even light engine load operation deflects the 

PRP spring system; however, high engine load 

operation deflects the upper piston further. This 

upper piston deflection controlled by the spring 

system limits the peak cylinder pressure and 

temperature. The expected result is lower engine-out 

NOx at the same engine efficiency and power output. 

Lower engine friction and noise are also anticipated 

outcomes.

Approach

A careful balance of analysis and experimental 

techniques are employed and analysis tools are 

utilized with designed experiment techniques to 

quickly sort the many possible variables. For engine 

simulation, the University of Michigan Diesel 

Engine Simulation and Spark Ignition Simulation 

codes are being utilized. The commercial AVL 

"Boost" code is also being used for the diesel 

simulation because of its emission prediction 

capability. The PRP dynamic modeling is being 

done with the University of Michigan code, based on 

SAE Belleville spring references. Federal Mogul is 

performing finite element analysis (FEA) on the PRP 

including thermal, mechanical, and dynamic loads. 

Single cylinder engine testing will correlate the 

engine simulation models as well as demonstrate the 

capabilities of the PRP. Ricardo SI and CI Hydra 

engines (as well as associated emission, fuel, and 

torque instrumentation) will be used for experimental 

testing at the University of Michigan.

Business strategies were used to improve the 

possible transition from research to product 

Figure 2. Belleville washer spring set

Figure 3. Dynamic Model

Figure 4. PRP Compression Pressure Compared with 

Fixed Compression Ratio Pistons of 9.5:1 and 

12.5:1 at Idle, Road Load, and Full Load at 

3000 RPM
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

48

application. Utilizing a major automotive piston 

supplier to design, analyze, and prototype the PRP 

adds credibility and implementation readiness to the 

project. University graduate students are utilized to 

improve "out of the box thinking" and help train 

future automotive engineers. Utilizing single 

cylinder SI and CI engines allow efficiency and 

emissions effects to be isolated and quantified. It is 

well accepted that single cylinder engine results/

components can be readily applied to multi-cylinder 

engines.

Results

Spring set: Various spring types were 

investigated; however, the Belleville washer was 

chosen since it had the best configuration for this 

application, as well as the ability to carry high loads 

with small deflections. Engine simulation and 

experience were used to develop an initial spring preload and axial travel requirement. A spreadsheet was 

made to calculate spring force versus deflection, and 

an experiment was utilized to sort through the many 

variables including spring stacks in series, parallel, 

spring thickness, inside diameter, free height, etc. A 

three-spring set was developed, as shown in Figure 2. 

This spring set met the pre-load, spring rate, fatigue 

life, and package requirements.

Dynamic model: An initial model was used as 

shown in Figure 3. One of the few damping forces 

for this spring mass system is piston ring friction. 

However, ring friction is very small relative to the 

spring-set forces. The model predicts that the upper 

piston will oscillate relative to the lower piston well 

into the next engine-firing event. Experience has 

shown this to not be the case. To understand the 

dynamics of the system the spring-set pre-load needs 

to be added to the model.

SI analysis knock model: Several knock models 

were investigated to establish the maximum 

compression ratio. The best model was utilized to 

establish the highest part load compression ratio 

Figure 5. SI and CI Ricardo Hydra engines at the 

University of Michigan

Figure 6. PRP Initial Solid Model Design

At Pin = 1.0 bar (~100% max power)

Speed (rpm) BSFC baseline (g/kWh)

BSFC PRP 

(g/kWh)

% Improvement

1000 239.5 230.8 3.6

2000 237.3 228.1 3.9

3000 242.2 231.0 4.6

5500 268.6 245.0 8.8

At Pin = 0.7 bar (~60% max power)

Speed (rpm) BSFC baseline (g/kWh)

BSFC PRP 

(g/kWh)

% Improvement

1000 266.7 250.1 6.2

2000 266.9 249.0 6.7

3000 277.9 255.7 8.0

5500 331.9 294.0 11.4

At Pin = 0.5 bar (~34% max power)

Speed (rpm) BSFC baseline (g/kWh)

BSFC PRP 

(g/kWh)

% Improvement

1000 316.7 291.0 8.1

2000 321.0 291.4 9.2

3000 347.6 310.0 10.8

5500 499.9 413.4 17.3

Table 1. PRP Improvement of brake specific fuel 

consumption
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

49

desired (without knock). A compression ratio of 

12.5:1 was established for up to 70kPa intake 

manifold pressure (typical road load). The base 

compression ratio for the test engine is 9.5:1.

SI engine analysis, cylinder pressure versus load: 

To illustrate the function of the PRP, cylinder 

pressure versus crankshaft angle was plotted along 

with fixed CR pistons at 12.5:1 and 9.5:1. Figure 4 

shows the PRP follows the fixed 12.5:1 CR piston at 

low loads (c), but follows the fixed 9.5:1 CR piston 

at high load (a).

SI engine analysis, thermal efficiency: The 

engine efficiency improvement as a result of the PRP 

is shown in Table 1. The efficiency improvement 

ranged from 3.6 to 17.3% depending on the speed 

and load condition.

Ricardo Hydra test cell: Significant effort has 

been concentrated on installing the donated doubleended dynamometer with the Ricardo SI and CI 

Hydra engines. The SI engine has been recently test 

fired and is ready for baseline testing. The test set-up 

at the University of Michigan, W.E. Lay Automotive 

Laboratory, is shown in Figure 5.

PRP design status: Federal-Mogul has developed 

an initial solid model of the PRP for establishing the 

spring-set package. The initial design is shown in 

Figure 6.

Conclusions

Analysis results are encouraging enough to build 

prototype hardware. Engine testing will allow firm 

conclusions to be made. SI PRP engine testing is 

scheduled to be complete by the end of the second 

quarter (2001 calendar year). Testing of the CIDI 

engine is planned to begin in October of 2001.

List of Acronyms

CI Compression ignition

FEA Finite Element Analysis

NOx Nitric oxide gas emission

PRP Pressure Reactive Piston

SI Spark ignition
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

50

G. HCCI Combustion Fundamentals: In-Cylinder Diagnostics and Kinetic-Rate 

Computations

John E. Dec

Sandia National Laboratories

P.O. Box 969, MS 9053

Livermore, CA 94551-9699

(925) 294-3269, fax: (925) 294-1004, e-mail: jedec@sandia.gov

DOE Program Manager: Gurpreet Singh

(202) 586-2333, fax (202)586-1600; e-mail: gurpreet.singh@hq.doe.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

Contractor: Sandia National Laboratories, Livermore, CA

Prime DOE Contract Number: DE-AC04-94AL85000

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

3. Fundamental Combustion R&D

Objectives

• Apply advanced diagnostics to investigations of HCCI combustion fundamentals.

- Results will be passed to U.S. industry to help them overcome the technical barriers to the 

development of HCCI engines.

• Conduct chemical-kinetic rate computations of HCCI ignition timing for different fuels across a wide 

range of operating conditions.

Approach

• HCCI Engine Laboratory

- Install two HCCI research engines: 1) an all-metal engine to establish operating points and 

develop combustion-control strategies, and 2) an engine with full optical access for the application 

of advanced laser-based diagnostics.

• Chemical-kinetic rate computations

- Modify CHEMKIN for time-varying compression, and install the most recent full chemistry 

mechanisms for n-heptane and iso-octane.

- Conduct computations of HCCI ignition timing for two fuel types, a gasoline surrogate and a 

diesel surrogate, across a wide range of operating conditions to determine the relative merits of 

these two fuel types for HCCI engines.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

51

Accomplishments

• Two Cummins B-series engines have been obtained, and cylinder-head modifications for variableswirl operation have been completed. Modifications for single-cylinder laboratory operation are 

underway.

- Basic installation of the engines and dynamometer is nearly complete. This installation includes a 

specially-designed mounting system that allows the dynamometer to be easily switched between 

the two engines, saving space and reducing cost.

- Design of the engine subsystems is underway, including 1) intake flow metering and EGR 

simulation, 2) intake-charge temperature and pressure control, and 3) oil and water circulation 

systems for temperature control and preheating.

- Initial design of the optically accessible engine is underway.

• Conducted a computational study of HCCI ignition timing across a wide range of operating conditions 

using CHEMKIN with the latest chemical mechanisms from LLNL.

- Used n-heptane as a kinetic-rate surrogate for diesel-fuel and iso-octane as a kinetic surrogate for 

gasoline to compare the ignition behavior of these two classes of fuels.

- Investigated the effects of these two fuel-types on HCCI engine design and operating sensitivity, 

including the effects of compression ratio, intake temperature and pressure, fuel loading, engine 

speed, and intake heating with EGR.

Future Directions

• Complete installation and shakedown testing of the all-metal engine and the various engine 

subsystems. Expect all-metal engine to become operational during FY 2001.

• Conduct initial HCCI experiments.

- Establish a base operating point, guided by CHEMKIN results.

- Begin an investigation of the operating range and sensitivity by systematically varying conditions 

about the base point and comparing results with CHEMKIN calculations.

• Design and acquire the optical-access engine components, including extended cylinder and piston, 

windows, drop-down liner for rapid cleaning, and transparent-cylinder option.

• Continue CHEMKIN calculations to support metal-engine experiments.

• Obtain a variable valve timing system (VVT) to improve laboratory throughput and to provide skipfire operation for the optical engine. This is contingent on sufficient funding.

Introduction

Homogeneous charge, compression ignition 

(HCCI) engines have advantages in terms of 

efficiency and reduced emissions over conventional 

internal combustion engines. They have been shown 

to be capable of providing diesel-like efficiencies 

with very low emissions of particulate and NOx. 

Although the basic principles of HCCI have been 

known for many years, a more comprehensive 

understanding HCCI engine combustion is lacking, 

and research is required to overcome the technical 

barriers to its implementation in a practical engine. 

Some of the areas requiring research include: control 

of ignition timing over the load/speed map, 

controlling the heat-release rate, the source and 

controlling factors of hydrocarbon emissions, and the 

effects of partial charge stratification (both in 

temperature and mixture space).
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

52

The objective of the current project is to develop 

the fundamental understanding necessary to 

overcome these barriers challenging HCCI. To 

achieve this objective, an HCCI engine laboratory 

will be equipped with two HCCI engines. One will 

be an all-metal engine which will be used to establish 

operating points, develop combustion-control 

strategies, and investigate emissions. The second 

will be an optically accessible engine which will be 

used to apply advanced laser diagnostics to the incylinder processes. In addition, computational 

modeling has been applied to determine the effects of 

fuel-type on HCCI ignition timing for a range of 

operating conditions. This research project is being 

conducted in close cooperation with both the 

automotive and heavy-duty diesel industries, with the 

results presented at the cross-cut diesel CRADA 

meetings.

Approach

Since no HCCI production engines exist today, 

two Cummins B-series diesel engines are being 

converted into the HCCI research engines. This 

SUV-sized engine was selected as being capable of 

providing an operating range relevant to both 

automotive and heavy-duty manufacturers. The sixcylinder production engines are being converted for 

balanced single-cylinder operation and mounted on 

either end of a double-ended dynamometer. Initially, 

they will be equipped with a fully premixed fueling 

system, but port fuel injection and direct in-cylinder 

fuel injection are planned for future studies. The 

laboratory will be equipped to handle a range of fuel 

types and to precisely control engine operating 

parameters, including intake mixture, temperature, 

and pressure, across a wide range of conditions.

Because the HCCI ignition and combustion 

processes are predominantly controlled by chemicalkinetic reaction rates, kinetic rate computations are 

also being conducted to develop a better 

understanding of the ignition behavior of different 

classes of fuels across the expected operating range. 

This is being accomplished using the CHEMKIN 

code, modified to allow time-varying compression, 

Figure 1. The HCCI Engine Combustion Laboratory, 

showing the installation of the two base 

engines and dynamometer on the vibrationisolation pad.

Figure 2a. CHEMKIN calculations of gas temperature as 

function of crankangle (360o = TDC), showing 

the change in HCCI ignition timing with 

changes in compression ratio for the diesel-fuel 

surrogate (n-heptane).

Figure 2b. CHEMKIN calculations showing the change in 

HCCI ignition timing with changes in 

compression ratio for the gasoline surrogate 

(iso-octane).
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

53

using the full chemistry mechanisms for n-heptane 

and iso-octane (from LLNL). These two fuels were 

selected because their detailed kinetic mechanisms 

are known and their ignition chemistry spans the 

range of octane and cetane numbers typical of both 

diesel-fuel and gasoline. This modeling approach, 

which treats the charge as a single lumped volume, 

has been shown to provide a good indication of 

HCCI ignition timing [1]; however, the model is not 

intended for predicting combustion rates and peak 

temperatures, which will be overestimated because 

they are strongly dependent on spatial 

inhomogeneities.

Results

Substantial progress has been made in enhancing 

laboratory capability. This includes installing a 

vibration-isolation pad, a compressor for the intakeair supply, a gas-supply system for the laboratory 

burner and for the engine (simulated EGR gases and 

gaseous-fuel capability), and installation of the 

electrical power for the dynamometer, compressor, 

lasers, heaters, and pumps. The engine and 

dynamometer mounts and couplings have been 

designed and fabricated, and the engines and 

dynamometer have been installed on the isolation 

pad as shown in Figure 1. Two production cylinder 

heads have been modified for variable swirl 

capability and flow-bench testing is complete. In 

addition, the design of the various engine subsystems 

(e.g. intake flow metering, intake-charge 

conditioning, and water and oil heating-andcirculating systems) are underway, as is the initial 

design of the optical engine.

Concurrent with the laboratory construction, a 

computational investigation has been conducted of 

the effects of fuel type on HCCI ignition timing 

across a wide range of operating conditions. 

Specifically, the influences of compression ratio 

(CR), intake temperature, equivalence ratio, engine 

speed, and exhaust gas recirculation (EGR) on 

ignition timing were investigated for two surrogate 

fuels: n-heptane, which has chemistry representative 

of diesel fuel, and iso-octane, which is representative 

of gasoline. As shown in Figures 2a and 2b, ignition 

chemistry is quite different for these two fuels. For 

the diesel surrogate (Figure 2a), ignition occurs in 

two-stages beginning at a temperature of about 800 

Figure 3a. CHEMKIN calculations showing the effect of 

changes in fuel load on HCCI ignition timing 

for the diesel-fuel surrogate (n-heptane).

Figure 3b. CHEMKIN calculations showing the effect of 

changes in fuel load on HCCI ignition timing 

for the gasoline surrogate (iso-octane).

Figure 4a. CHEMKIN calculations showing the effect of 

engine speed on ignition HCCI ignition timing 

for the diesel-fuel surrogate (n-heptane).
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

54

K. This limits the compression ratio to about 13 and 

the efficiency to less than that of a diesel engine, in 

agreement with engine tests in the literature [2]. In 

contrast, the gasoline surrogate (Figure 2b) allows 

compression to higher temperatures with ignition 

occurring in a single stage at about 1100 K. This 

permits higher compression ratios and therefore 

higher efficiencies. The compression ratio for best 

ignition timing in Figure 2b is 21. Although this is 

above the optimal range of 17-19, the compression 

ratio could be lowered by the use of hot EGR or a 

lower octane fuel (e.g. 87-octane gasoline), if 

necessary. However, engine tests have shown that 

the compression ratio actually required is somewhat 

lower than that indicated by the lump-volume model, 

presumably due to inhomogeneities in the charge [3]. 

HCCI engine tests have also shown that using 

gasoline-like fuels such as iso-octane, HCCI engines 

can achieve diesel-like efficiencies and low NOx

emissions [3,4].

Figures 3a and 3b show the effects of changing 

the fuel loading, and Figures 4a and 4b show the 

effects of changing engine speed for the diesel and 

gasoline surrogates. As shown in Figure 3a, the twostage ignition of a diesel-like fuel results in a wide 

variation in ignition timing with changes in fuel load. 

Low loads of an equivalence ratio (φ) of 0.2 or less 

never fully ignite, while high loads (φ = 0.5 to 0.65) 

ignite near TDC. However, with a single-stage 

ignition fuel, ignition timing varies only a few 

degrees from low to high load (φ = 0.1 to 0.65), as 

shown in Figure 3b. Similarly, the gasoline surrogate 

is less affected by changes in engine speed than is the 

diesel surrogate, although both fuels show some 

sensitivity (Figure 4). A complete discussion of this 

investigation, including the effects of EGR may be 

found in our Combustion Symposium paper listed 

below.

Conclusions

Chemical-kinetic rate computations have shown 

how HCCI ignition timing is affected by a range of 

operating conditions for both diesel and gasoline-like 

fuels. This study indicates that single-stage ignition 

(gasoline-like) fuels could have significant 

advantages for HCCI, both in their potential for a 

high-efficiency engine and for controlling ignition 

timing across the load/speed map.

List of References

1. Aceves, S.M., Flowers, D.L., Westbrook, C.K., 

Smith, J.R., Pitz, W., Dibble, R., Christensen, 

M., and Johansson, B., "A Multi-Zone Model for 

Prediction of HCCI Combustion and Emissions," 

SAE paper number 2000-01-327, 2000.

2. Gray, A.W. and Ryan, T.W. III, "Homogeneous 

Charge Compression Ignition (HCCI) of Diesel 

Fuel," SAE paper number 971676, 1997.

3. Christensen, M., Johansson, B., Amneus, P., and 

Mauss, F., "Supercharged Homogeneous Charge 

Compression Ignition," SAE paper number 

980787, 1998.

4. Christensen, M., Johansson, B., and Einewall, P., 

"Homogeneous Charge Compression Ignition 

(HCCI) Using Iso-octane, Ethanol and Natural 

Gas - A Comparison with Spark Ignition 

Operation", SAE paper number 972874, 1997.

List of Publications/Presentations

1. Kelly-Zion, P. L., and Dec, J. E. "A 

Computational Study of the Effect of Fuel Type 

on Ignition Time in HCCI Engines," accepted for 

presentation at and publication in the 

proceedings of the 2000 International 

Combustion Symposium.

2. J. E. Dec, "HCCI: the Need, Progress, and 

Plans," Cross-Cut Diesel CRADA Meeting, Oct. 

1999.

Figure 4b. CHEMKIN calculations showing the effect of 

engine speed on ignition HCCI ignition timing 

for the gasoline surrogate (iso-octane).
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

55

3. J. E. Dec, HCCI Project Report, SIDI CRADA 

Meeting, Jan. 2000.

4. J. E. Dec and P. L. Kelly-Zion, "The Effects of 

Fuel Type on Ignition Timing in HCCI Engines," 

DOE CIDI Combustion, Emission Control, and 

Fuels Review, May 22-24, 2000.

5. J. E. Dec and P. L. Kelly-Zion, HCCI Project 

Report, Cross-Cut Diesel CRADA Meeting, May 

31 - June 1, 2000.

List of Acronyms

CHEMKIN Name of chemical-kinetic code

CR Compression Ratio

EGR Exhaust Gas Recirculation

HCCI Homogeneous Charge Compression 

Ignition

LLNL Lawrence Livermore National 

Laboratory

SUV Sport Utility Vehicle

TDC Top Dead Center

VVT Variable Valve Timing 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

56

H. Camless Variable Valve Timing System for a High-speed CIDI Engine

Tsu-Chin (T-C.) Tsao

Mechanical and Aerospace Engineering Department

University of California, Los Angeles

Box 951597

Los Angeles, CA 90095-1597

(310) 206-2819, fax: (310) 206-2302, e-mail: ttsao@seas.ucla.edu

DOE Program Manager: Kenneth Howden

(202) 586-3631, fax: (202) 586-9811, e-mail: ken.howden@ee.doe.gov

Subcontractor: University of California, Santa Barbara, CA

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

2. Sensors and Controls

Objectives

• Develop a system dynamics model and simulation program for the proposed electrohydraulic camless 

valvetrain (ECV) actuating system.

• Develop electronic control methods for valve timing, lift, soft seating, and multiple valve operations.

• Integrate an instrumented variable valve timing system on an engine head with electronic drivers and 

control interface software. The 16-valve system shall be fully electronically driven via triggering from 

the crank angle of an engine running in parallel.

• Characterize the system performance envelope, energy consumption and sensitivity to environmental 

conditions through both simulation and experiment.

• Develop a system and control-oriented dynamic model of CIDI engines and investigate the feasibility 

of the control configurations and strategies using the proposed actuating system. 

Approach

• Task 1: Perform system design, integration, and instrumentation.

• Task 2: Perform dynamic modeling, simulation, and control of the ECV actuating system.

• Task 3: Implement valve motion control and measure the valve performance and energy consumption. 

Compare the test results with Task 2 simulation results.

• Task 4: Perform system oriented engine-wide modeling of the actuating systems for CIDI engine 

operations.

• Task 5: Perform preliminary engineering and economic analysis according to the test and model 

simulation results. 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

57

Accomplishments

• The ECV system dynamics model and simulation programs have been developed and calibrated. The 

simulation results agree with experimental data.

• Adaptive nonlinear feedforward control for valve lift has been developed and implemented to 

successfully improve transient response time, eliminate transient overshoot, and enhance robust 

performance against operating condition changes.

• Eight-valve ECV subsystem has been demonstrated on the hardware test rig for simulated engine 

speed up to 5500 rpm.

• The ECV system has been fully electronically driven via triggering from the crank angle of an engine 

running in parallel. Furthermore, the ECV has been demonstrated to start up and run single cylinder 

engine combustion. The engine torque was controlled by the valve timing instead of by the throttle 

opening.

• The ECV system’s energy consumption has been measured to be comparable to that of cam driven 

valvetrain. The ECV has also been shown to operate using engine oil or diesel fuel instead of 

hydraulic oil.

• A system and control-oriented dynamic model of CIDI engines has been developed. 

Future Directions

• Refine the system and component design for higher efficiency and consistency.

• Develop electronic control algorithms/software/hardware for valve timing, lift, soft seating, and 

closing control.

• Integrate the variable valve timing system on small high-speed CIDI engines for testing of camless 

CIDI engine operation.

• Characterize the ECV performance envelope, energy consumption, open loop and closed loop 

repeatability, and sensitivity to environmental conditions through both simulation and experiment.

• Develop and test system and control strategies for emission control and torque control of CIDI engines 

by using the variable valve timing capability.

Introduction

Most existing variable-timing systems, which 

perform a camshaft phase shift or a switch to another 

cam lobe profile, offer measurable improvements at 

some engine operating points [1,2]. A 

microprocessor controlled camless valvetrain, which 

continuously adjusts the parameters of valve motion 

with changing operating conditions, offers much 

more flexibility and potential benefits as they allow 

more complete optimization of engine events over 

the entire operating speed range. However, such 

devices can be complex, bulky, and relatively 

expensive, so their applications tend to be limited. 

An electrohydraulic camless valvetrain (ECV) was 

first conceived by Ford researchers [3]. This device 

Figure 1. Electrohydraulic Camless Valvetrain 

Components
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

58

is compact and relatively simple. The goal of this 

research effort is to investigate the feasibility, 

address the technical challenges, and develop the 

enabling control capability of such a device for 

camless operation of small compression ignition 

direct injection (CIDI) engines.

Results

An experimental ECV has been completed. 

Figures 1 and 2 show the ECV components and the 

instrumented system. Dynamic models, simulation 

programs, and cyclic variability tests have been 

conducted and calibrated by the experimental data 

[4,5]. To account for the system non-linearities and 

the variations with the environmental conditions, and 

to realize the optimal engine operations at various 

loads and speeds, the engine valve motion must be 

precisely controlled. Adaptive nonlinear feedforward 

control [6] was developed and tested successfully. 

Figure 3 demonstrates that the adaptive control has 

faster transient response and less overshoot (within 5 

cycles) than PID (proportional-integral-derivative) 

control (about 10 cycles in the best case). Tests for 

fast speed transitions and fluids of different 

viscosities including diesel fuel were also 

successfully conducted.

To make use of the ECV’s potential benefits, the 

power required to run the system must be at least 

comparable to the camshaft frictional loss. The ECV 

power consumption is as follows:

Solenoid electrical power consumption + (Intake Lift 

+ Exhaust Lift) * 2 * piston area * (1- ECV 

hydraulic recovery %) / hydraulic supply efficiency

Figure 2. Experimental Setup

Figure 3. Transient response for valve lift step changes

Figure 4. Predicted Energy Recovery Improvement by 

Increasing the Solenoid Speed

Figure 5. Camless Engine Torque Control Experimental 

Test by Variable Intake Closing Time
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

59

The energy recovery for the ECV system was 

measured to be about 10% for the present solenoid 

valves. The electrical power required to operate the 

solenoids was also measured. Using these figures, 

the ECV power consumption in turn was calculated. 

The worst case (maximum lift for full load) ECV 

power is similar to that of the finger rocker arms, but 

larger than the rolling finger followers. Faster 

solenoid closing time would generate high hydraulic 

energy recovery, as predicted by the model 

prediction shown in Figure 4 [6]. To further reduce 

the power consumption, the valve leakage must be 

reduced and the solenoid response must be increased.

The ECV was mounted on an engine to test 

single cylinder start-up and firing. During these tests 

the torque of the engine was controlled with the ECV 

valve timing with the throttle fully open, as Figure 5 

shows [6]. Models for engine air breathing and 

control for cylinder-to-cylinder balancing have also 

been developed [7].

Conclusions

The electrohydraulic camless valvetrain 

proposed in this project offers a continuously 

variable and independent control of all aspects of 

valve motion. Freedom to optimize all parameters of 

valve motion for each engine operating condition is 

expected to result in better fuel economy, higher 

torque and power, improved idle stability, lower 

exhaust emissions and a number of other benefits and 

possibilities. The results obtained from this 

investigation suggest the technical feasibility for use 

in CIDI engines is good. Precise and agile valve 

motion control is of critical importance to make use 

of the variable valve timing and variable valve lift 

capability for optimal engine operations. Further 

research efforts should be directed to improving the 

valvetrain dynamic response, soft seating, and energy 

efficiency, and developing a prototype camless CIDI 

test engine for emission and torque control and 

performance evaluation.

List of References

1. Ahmad T. and Theobald M. A., "A Survey of 

Variable Valve Actuation Technology," SAE 

Paper No. 891674.b

2. Asmus T., "Perspectives on Applications of 

Variable Valve Timing", SAE paper 910445.

3. Schechter M. M. and Levin M. B., 1996, 

"Camless Engine," SAE Paper No. 960581.

4. Kim D., Anderson M., Tsao T. C., and Levin M. 

"A Dynamic Model of a Springless 

Electrohydraulic Camless Valvetrain System," 

SAE paper 97024

5. Anderson M., Tsao T.-C. ,and Levin M., 

"Adaptive Lift Control for a Camless 

Electrohydraulic Valvetrain," SAE Paper No. 

981029.

6. Tai C., "Adaptive Feedforward with Feedback 

Control of an Electrohydraulic Camless 

Valvetrain," M.S. Thesis, University of Illinois at 

Urbana-Chmpaign, IL, 1999.

7. Ashhab M. S., Stefanopoulou A. G., Cook J., and 

Levin M., "Camless Engine Cotrol for Robust 

Unthrottled Operation," SAE Paper No. 981031.

List of Publications/Presentations

1. Tai C., "Adaptive Nonlinear Feedforward with 

Feedback Control of an Electrohydraulic 

Camless Valvetrain," M.S. Thesis, University of 

Illinois at Urbana-Chmpaign, IL, 1999.

2. Tsao, T-C., "Variable Valve Timing System for 

Camless Engine Operations," Cooperative 

Automotive Research for Advanced Technology 

Forum, Troy Mich., September, 1999.

3. Tai, C., Tsao, T-C., Levin, M. B., "Adaptive 

Nonlinear Feedforward Control of an 

Electrohydraulic Camless Valvetrain," American 

Control Conference, Chicago, IL., June 2000.

List of Acronyms

CIDI compression ignition direct injection

ECV electrohydraulic camless valvetrain

BMEP brake mean effective pressure

PID proportional-integral-derivative 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

60

I. Low-Friction Coatings for CIDI Fuel Injection System Components

George R. Fenske (primary contact), Oyelayo Ajayi, John Woodford, and Ali Erdemir

Argonne National Laboratory 9700 South Cass Avenue, ET-212

Argonne, Illinois 60439

(630) 252-5190, fax: (630) 252-4798, e-mail: gfenske@anl.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

DOE Program Manager: Pat Davis

(202) 586-8061, fax (202) 586-9811, e-mail: patrick.davis@ee.doe.gov

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

C. Cost

Tasks

1a. Advanced Fuel Systems

Objectives

• Determine the impact of advanced fuel system strategies (advanced designs and low-emission fuels) 

on the reliability and durability of materials and surface treatments of critical fuel system components.

• Evaluate the performance of amorphous carbon coatings and other advanced surface treatments 

subjected to low-emission fuels.

• Determine and resolve critical issue(s) relating to the scale-up of advanced surface modification 

processes used to improve the reliability and durability of critical fuel system components.

• Determine the effect of EGR on the tribological properties of engine lubricants and characterize the 

potential of advanced surface treatments to improve reliability and durability of critical engine 

components subjected to EGR contaminated lubricants.

Approach

• Perform benchtop friction and wear tests to characterize the friction and wear properties of baseline 

materials and coatings subjected to tribological environments prototypical of advanced fuel systems 

and fuels.

• Deposit near frictionless carbon (NFC), commercial diamondlike carbon, and other commercial 

coatings (e.g. CrN, TiN, etc.), and, evaluate tribological performance.

• Deposit NFC (and commercial coatings) on prototype components for reliability/durability evaluation 

on fuel system rigs.

• Procure and modify commercial-size plasma-assisted deposition rig for NFC coatings.

• Validate production of NFC coatings with large-batch size plasma assisted chemical vapor deposition 

(PACVD) unit.

• Transfer technology to industrial partner(s).

• Characterize engine lubricants exposed to differing levels of EGR.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

61

• Perform benchtop tests to characterize tribological properties of materials exposed to EGR.

• Correlate benchtop test results with field results.

• Develop advanced materials and surface treatments for high EGR levels. 

Accomplishments

• Protocols for evaluation of materials, and coated components were selected and developed at ANL.

• Preliminary benchtop tribological testing of baseline materials, NFC, and limited commercial 

coatings in diesel fuels completed.

• Prototype fuel system components were coated and tested.

• Commercial PACVD unit procurement was initiated.

• Completed preliminary analysis of engine lubricants exposed to different levels of EGR

Future Directions

• Analysis and comparison of failure modes & wear modes of baseline and advanced coatings under 

stringent tribological conditions (low-lubricity fuels and EGR-contaminated lubricants).

• Demonstration of NFC coating on a large batch basis.

Introduction

Reduction of emissions from CIDI engines will 

require low sulfur and low aromatic fuels to 

minimize degradation of aftertreatment devices, 

reduce particulate formation, and minimize lubricant 

degradation. Such fuels, however, have poor 

lubricity, and can increase the occurrence of 

catastrophic scuffing failure as well as reduce longterm durability of critical components. Reducing 

emissions from CIDI engines may also require lowemission lubricant additive packages that have lower 

levels of sulfur, phosphorous, and metallic based 

compounds critical for anti-wear and low-friction 

properties. Furthermore, more aggressive engine 

environments resulting from: the recirculation of 

combustion products (particulates and acids) through 

the use of EGR to reduce NOx, downsizing and 

weight reduction of components, higher injection 

pressures, and higher speeds will exacerbate the 

ability of current materials and lubricants to meet 

reliability and durability requirements

Approach

The development of NFC coatings for advanced 

CIDI fuel system components involves optimization 

of the NFC deposition process to minimize 

catastrophic scuffing and long-term wear. Benchtop 

friction and wear protocols were employed at 

Argonne to first characterize the scuffing and wear 

performance of current materials to serve as a 

baseline for comparison with NFC coatings as well 

as other commercially available (e.g. DLCs, CrN, 

TiN, etc.) coatings. Commercial coatings applied to 

benchtop samples are obtained from different 

suppliers and subjected to the same test protocols as 

those for the baseline and NFC coated specimens to 

obtain information on the scuffing severity index (the 

product of the critical load, velocity, and friction 

coefficient at the point where scuffing occurs), as 

well as the wear rate.

Figure 1. Photograph of different engine components 

being coated with NFC coatings
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

62

The process used to deposit the NFC coatings is 

illustrated in Figure 1. The process is a PACVD 

technique that utilizes a proprietary gas chemistry 

and plasma potential to form an amorphous carbon 

coating with unique chemical bonding. Tribological 

performance studies in dry inert environments have 

repeatedly demonstrated extremely good properties 

with friction coefficients as low as 0.001 with wear 

rates in the 10-10 mm3

/N-m range. The current 

program addresses the properties of NFC coatings in 

environments prototypical of engines, with emphasis 

on assessing the role of sulfur in the fuel on scuffing 

and wear.

The scuffing resistance was evaluated using a 

reciprocating pin-on-flat configuration such as that 

illustrated in Figure 2. Scuffing tests were conducted 

at different constant contact loads and with a stepincrease in sliding speed until scuffing occurred. 

Tests were conducted in the load range of 150-400 N, 

corresponding to initial Hertzian stress of 1.1-1.8 

GPa, 1-15 Hz reciprocating frequency, and a stroke 

length of about 20 mm, translating to a sliding speed 

in the range of 0.04-0.6 m/s. The results of a 

preliminary set of tests is shown in Figure 3 which 

compares the scuffing resistance of conventional 

diesel fuel (500 ppm S maximum, typically 

approximately 350 ppm S) with that of a synthetic 

diesel fuel with 0 ppm sulfur. The data illustrate two 

main points: first, the scuffing resistance provided by 

the synthetic fuel is less than that of the conventional 

diesel fuel; and second, the use of the NFC coating 

increased the scuffing resistance by an order of 

magnitude. Because the chemical nature of the 

uncoated steel surface is different from that of the 

NFC coating, the manner in which sulfur and other 

additives interact with these surfaces is also different. 

This leads to the result that the scuffing resistance of 

uncoated steel is reduced with synthetic diesel 

relative to conventional diesel, while the scuffing 

resistance of NFC-coated steel is increased with 

synthetic diesel relative to conventional diesel. 

Microscopic analysis of worn areas indicate the NFC 

coating does not actually scuff, and that scuffing only 

occurred after the NFC coating was either worn away 

or spalled under extremely high loads revealing an 

uncoated steel surface.

Durability behavior was examined using a ballon-three-disc (BOTD) configuration. In contrast to 

the reciprocating motion employed to study the 

scuffing behavior, the BOTD studies involved a 

continuous, unidirectional sliding motion. Figure 4 

illustrates the effect of sulfur on the durability of 

steel as well as the effect of NFC coatings. As seen 

Figure 2. Reciprocating pin-on-flat configuration used to 

evaluate scuffing failure.

Figure 3. Scuffing severity index of uncoated and NFC 

coated steel in conventional diesel and 

synthetic (Fischer Tropsch) diesel fuel

Figure 4. Effect of low-sulfur fuels on the durability 

(wear rates) of uncoated and NFC coated steel
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

63

in Figure 4, as the sulfur content of the diesel fuel is 

reduced to 140 ppm S to 3 ppm S, and then to 0 ppm 

S (Fischer-Tropsch - FT), the wear rate of an 

uncoated hardened steel increases by a factor of 34. 

One sees a similar trend for the NFC coated discs, 

however, the magnitude of the increase is 

significantly lower (a factor of approximately 5), and 

the absolute values for the NFC coated surfaces are 

all significantly lower than the best uncoated steel 

and conventional diesel fuel. In other words, the 

highest wear rate (2.1) for the NFC coated samples 

(for FT fuel) was less than half that of the lowest 

wear rate (5.2) for the uncoated steel and 

conventional diesel fuel.

The reliability (e.g the ability to withstand shortterm catastrophic failure such as scuffing) and 

durability (e.g. the ability to withstand long-term 

wear that leads to gradual degradation) of fuel 

delivery components are not only affected by sulfur, 

but also by aromatic compounds. Sulfur is known to 

provide extreme pressure protection by the formation 

of protective boundary layer films and thus will have 

a more dramatic impact on improving scuffing 

resistance. Aromatics increase the effective viscosity 

of the fuel resulting in thicker fluid films that 

minimize interactions between surface asperities and 

hence have a greater impact on long term wear. The 

petroleum-based fuels used in these tests had 

different levels of aromatics, while the FT fuel 

contained no aromatics. Thus, some of the 

differences seen in these figures are in part due to 

different aromatic contents (although all, with the 

exception of the FT fuel, were in the 20 to 30% 

level). However, tests are currently in progress using 

a series of DECSE fuels that were formulated in such 

a manner that the only variable is the sulfur content 

(ranging from 3 ppm to 471 ppm).

A series of diesel injector plungers were coated 

and delivered to our industrial partner for a series of 

seizure tests, in which an injector is paired with an 

undersized injector body to ensure a tight fit. The 

assembled unit is then subjected to a series of runs in 

which the injection pressure is gradually increased 

until the injector seizes. For a typical uncoated, 

hardened plunger, seizure occurs at approximately 

1000 bar, while for a plunger coated with a 

commercial TiN coating, seizure occurs at 

approximately 3000 bar. The seizure limit for the 

first set of NFC coated plungers exceed 3500 bar, far 

above any values observed to date.

Because of these exceptional results, a number of 

fuel system suppliers are interested in using this 

technology in production. We are currently 

collaborating with a number of PACVD equipment 

OEMs to transfer the NFC process technology in this 

area, and anticipate receiving a state-of-the-art unit 

that will be modified to accept the NFC process.

Future Directions

Efforts are also being pursued to evaluate the 

properties of NFC coatings for other engine 

components. One such program is with a diesel 

engine OEM. The focus of this project is to evaluate 

the effect that EGR will have on the lubricating 

properties of engine lubricants that are exposed to 

higher levels of soot and acid. Traditional 

approaches to solve the EGR problem would be to 

increase the detergent levels and acid neutralizing 

additives in the oil. However, in light of the need to 

minimize S, P, and metallic compounds in engine 

lubes due to their deleterious effect on aftertreatment 

devices, this may not be a viable approach. 

Consequently efforts are in progress to determine the 

impact of using higher levels of EGR on the 

lubricating properties of engine lubes, and 

determining the role of advanced coatings as a mean 

to mitigate these effects.

List of Publications

1. O.O. Ajayi, G.R. Fenske, A. Erdimir, J. 

Woodford, J. Sitts, and K. Griffey, "Low-Friction 

Coatings for Air Bearings in Fuel Cell Air 

Compressors", in SAE Paper 2000-01-1536.

2. M.F. Alzoubi, O.O. Ajayi, O.L. Eryilmaz, O. 

Ozturk, A. Erdimir, and G.R. Fenske, 

"Tribological Behavior of Near-Frictionless 

Carbon Coatings in High- and Low-Sulfur Diesel 

Fuels", SAE Paper 2000-01-1548.

3. A. Erdimir, O. Ozturk, M. Alzoubi, J. Woodford, 

O. O. Ajayi, and G.R. Fenske, "Near-Frictionless 

Carbon Coatings for Use in Fuel Injectors and 

Pump Systems Operating with Low-Sulfur 

Diesel Fuels", SAE Paper 2000-01-0518.

4. O.O. Ajayi, M. Alzoubi, A. Erdimir, G.R. 

Fenske, O.L. Eryilmaz, and S. Zimmerman, 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

64

"Tribological Performance of NFC Coatings 

under Oil Lubrication", SAE Paper 2000-01-

1547.

List of Presentations

1. A. Erdimir, O.L. Eryilmaz, and G.R. Fenske, 

"Synthesis of Diamondlike Carbon Films with 

Superlow Friction and Wear Properties", 

presented at 46th International Symposium, 

AVS, October 25-29, 1999, Seattle, WA.

2. A. Erdimir, O.L. Eryilmaz, I.B. Nilufer, and G.R. 

Fenske, "Synthesis of Superlow Friction Carbon 

Films from Highly Hydrogenated Methane 

Plasmas", presented at International Conference 

on Metallurgical Coatings and Thin Films, April 

9-14, 2000, San Diego, CA.

List of Acronyms

ANL Argonne National Laboratory

BOTD Ball on three disc

CIDI Compression Ignition Direct 

Injection

DECSE Diesel Emission Control-Sulfur 

Effects

DLC Diamond-Like Carbon

EGR Exhaust Gas Recirculation

FT Fischer-Tropsch Diesel Fuel

NFC Near-Frictionless Coatings

OEM Original Equipment Manufacturer

P Phosphorus

PACVD Plasma assisted chemical vapor 

deposition

S Sulfur
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

65

J. Fuel Spray Measurement Using X-Rays

Jin Wang (primary contact), Ramesh Poola, and Roy Cuenca

Argonne National Laboratory

9700 South Cass Avenue

Argonne, IL 60439

(630) 252-9125, fax: (630) 252-9303, e-mail: wangj@aps.anl.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax (202) 586-9811, e-mail: kathi.epping@ee.doe.gov

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

1. Fuel Systems R&D

Objectives

• Understand the fuel structure and dynamics in the region close to nozzles with small orifice diameter 

operated at high injection pressure.

• Develop highly quantitative and time resolved methods to achieve the above goal.

• Establish a knowledge base regarding spray breakup mechanisms and droplet interactions as a key to 

realistic computational modeling.

Approach

• Stage 1: Study the feasibility of using synchrotron x-rays for imaging diesel fuel sprays in a timeresolved manner (with time resolution of better than 1 microsecond).

• Stage 2: Analyze the image data for qualitative evaluation of the spray characteristics.

• Stage 3: Use 2-dimensional x-ray detectors to collect the radiographic data more efficiently.

• Stage 4. Understand high-speed sprays by theoretical modeling and computational approaches.

Accomplishments

• Evaluated sprays of a Bosch injector under various injection conditions with both high spatial and 

temporal resolution.

• Collected the x-ray spray image data using 2-D detectors successfully.

Future Directions

• Develop x-ray optics suited for 2-D data collection to improve the productivity of the experiments.

• Perform the spray measurement under higher ambient pressure.

• Develop 2-phase models near the injection nozzles.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

66

Introduction

Detailed analysis of the in-cylinder fuel spray 

process has been recognized as an important step in 

the overall aim of increasing combustion efficiency 

and reducing emission of pollutants, in particular 

from diesel engines. This has spurred considerable 

activity in the development of both optical and nonoptical fuel injector spray measurement techniques. 

Despite significant advances in laser diagnostics over 

the last 20 years, the region close to the nozzle has 

remained impenetrable to experiments designed to 

acquire quantitative information due to multiple 

scattering caused by the large number and high 

density of droplets in the region. While other 

researchers are looking into the possibility of using 

lasers of ultra-high power and ultra-short pulse width 

to study this region, we report here on the 

development of a new non-intrusive and quantitative 

technique to characterize the dense part of the fuel 

spray using monochromatic x-ray absorption 

techniques. X-rays are highly penetrative in 

materials composed of extremely dense droplets 

made of low-Z materials (materials made up of low 

atomic weight substances). This makes x-rays a 

most suitable tool for fuel spray studies to overcome 

the difficulties, such as multiple scattering, 

encountered by conventional methods utilizing 

visible light. At the Advanced Photon Source (APS), 

we have developed a technique, utilizing x-ray 

absorption of monochromatic radiation, to 

quantitatively determine the fuel density distribution 

in this optically impenetrable region with a time 

resolution better than one microsecond. The current 

quantitative measurements constitute the most 

detailed near-nozzle study of a fuel spray to date.

Approach

The fuel spray was generated using a highpressure injector typical of that found in a 

compression ignition, direct injection (CIDI) engine. 

The diesel fuel used in the test was doped with a 

cerium-containing additive in order to increase its xray absorption. Injection was performed into a spray 

chamber filled with inert gas at atmospheric pressure 

and at room temperature. SF6, a very heavy gas, was 

used to create a relatively dense ambient 

environment in the injection chamber. The 

experiments were performed at the 1-BM beamline 

of the Synchrotron Radiation Instrumentation 

Collaborative Access Team (SRI-CAT) at APS. A 

5.989 keV x-ray beam was initially focused and then 

collimated by a pair of X-Y slits to a size of 500 μm 

(horizontal) by 50 μm (vertical). The transient x-ray 

attenuation signal due to the fuel spray was measured 

by an avalanche photodiode (APD). The APD 

response was proportional to the beam intensity over 

the range used in our experiment and was recorded 

every 2 ns by a digitizing oscilloscope. Since the 

APD is a point detector, the injection chamber was 

scanned vertically and horizontally with respect to 

the x-ray beam, allowing the beam to probe various 

positions within the spray plume. The x-ray 

absorption technique using a monochromatic beam is 

distinguished from conventional measurements by 

the quantitative nature of the measurement. With 

proper calibration, the x-ray absorption directly 

yields the absolute fuel mass quantity in the beam 

and the mass distribution. 

A plot of the time-dependent x-ray transmission 

at positions 1 and 6 mm from the nozzle on the spray 

axis are shown in Figure 1. For the data taken at 1 

mm from the nozzle, it can be clearly seen that the 

spray arrives and leaves the beam spot at t = 0.11 and 

0.5 ms, respectively. The leading edge of the fuel 

spray appears very abruptly, indicating a very distinct 

boundary between ambient gas and fuel spray and a 

compressed layer after the sharp edge. At 6 mm from 

the nozzle on the spray axis, the front edge of the 

spray arrives at the measuring point at a later time 

(0.19 ms). The delay can be used to calculate the 

Figure 1. Time evolution of the x-ray transmission on the 

spray axis 1 mm (solid square) and 6 mm (open 

square) from the nozzle
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

67

speed of the front edge. The absorption of the body 

of the spray decreased significantly, indicating a 

much lower fuel volume fraction. 

Based on the transmission values and the mass 

calibration, the amount of fuel in the path of the 

beam can be determined in a time-resolved manner. 

The normalized density (volume fraction of fuel) 

distribution is plotted in Figure 2 for the leading edge 

of the spray (upper panel) and the main body of the 

spray (lower panel) at distances of 1 and 6 mm from 

the nozzle. The most striking feature of the plots in 

Figure 2 is that the density of the fuel spray was 

significantly less than that of the bulk liquid fuel, 

even as close as 1 mm from the nozzle. The main 

body of the spray, the region that has been termed the 

"intact liquid core", is actually composed of a liquid/

gas mixture. 

The speed of the leading edge has been 

determined in the experiment and is illustrated in 

Figure 3. The speed increased slightly after the spray 

exited the nozzle, and then maintained a nearly 

constant value slightly above the sonic speed in SF6

(about 140 m/s). Similarly, the speed of the trailing 

edge can also be derived (Figure 3). We note that the 

trailing edge traveled at a speed much higher than the 

sonic speed initially, and gradually, slowed down to a 

value close to that for the leading edge. Thus far, the 

trailing edge speed has never been determined by any 

other experiments. The trailing edge speed provides 

invaluable information about the dynamics of the 

spray, such as generation of shock waves in the 

injection chamber. 

Conclusions

In summary, by using monochromatic x-ray 

radiography, we have been able to study an optically 

dense region of the spray that has not been studied 

previously. The measurement is highly quantitative 

and time resolved. With further progress of this 

work, a detailed spray structure of the near-nozzle 

region will be elucidated. These results are essential 

to the development of accurate theoretical models of 

fuel sprays that will lead to better nozzle designs. In 

addition, the synchrotron-based, time-resolved 

monochromatic x-ray radiographic technique should 

prove its usefulness not only in the field of spray 

science and technology but also in research areas 

dealing with transient phenomena of optically 

opaque materials such as aerosols, and heavy 

element plasmas.

List of Publications

1. Powell, C.F., Y. Yue, R. Poola, and J.Wang, 

"Time-Resolved Measurements of Supersonic 

Fuel Sprays Using Synchrotron X-rays", 

submitted to the Journal of Synchrotron 

Radiation.

2. Poola, R., C.F. Powell, S. Gupta, A. McPherson, 

and J. Wang, "Development of a Quantitative 

Measurement of a Diesel Spray Core by Using 

Synchrotron X-rays", Proceedings of the Eighth 

Figure 2. Normalized radial distribution of the fuel 

density measured 1 and 6 mm from the nozzle 

at different instants in time (leading edge or 

main body of the spray intercepting the beam, 

respectively). A normalized density equal to 

unity implies the density of bulk liquid fuel 

(Injection pressure: 500 bar; Duration: 300 s).

Figure 3. Speed of the leading (solid line) and the trailing 

edge (dash) of the spray.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

68

International Conference on Liquid Atomization 

and Spray Systems, California, July 2000.

3. Yue, Y., C.F. Powell, R. Poola, and J. Wang, 

"Quantitative Measurement of Diesel Fuel Spray 

Characteristics in the Near-Nozzle Region by 

Using X-ray Absorption", submitted to 

Atomization and Sprays.

4. Schaller, J.K., U. Kunzi, C.F. Powell, Y. Yue, R. 

Poola, and J. Wang, "Investigations of the Diesel 

Injection Using Synchrotron X-rays for 

Quantitative Measurement of the Mass 

Distribution and a Piezo Electrical Sensor to 

Probe the Jet Force", Proceedings of ILASSEurope 2000, Darmstadt, Germany, September 

2000.

List of Acronyms

2-D Two-dimensional

APD Avalanche photodiode

APS Advanced Photon Source

CIDI Compression Ignition Direct 

Injection

keV Thousand electron volts

SF6 Sulfur hexaflouride

SRI-CAT Synchrotron Radiation 

Instrumentation Collaborative 

Access Team
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

69

IV. EXHAUST GAS NOX EMISSION CONTROL R&D 

A. Non-Thermal Plasma-Assisted Catalysis 

M. Lou Balmer (primary contact), Russ Tonkyn, Steve Barlow, Gary Maupin, and Alexander Panov

Pacific Northwest National Laboratory

P.O. Box 999, MSIN K8-93

Richland, WA 99352

(509) 376-2006, fax: (509) 376-5106, e-mail: lou.balmer@pnl.gov

Stephen D. Nunn

Oak Ridge National Laboratory

P.O. Box 2008, M/S 6087

Oak Ridge, TN 37831-6087

(865) 576-1668, fax: (865) 574-8271, e-mail: nunnsd@ornl.gov

DOE Program Manager: Kathi Epping 

(202) 586-7425, fax (202) 586-9811 email: Kathi.Epping@ee.doe.gov

CRADA Partner: Low Emissions Technologies Research and Development Partnership (Member 

Companies: Ford Motor Company, General Motors, and DaimlerChrysler Corporation)

Michael J. Royce (Primary Contact) DaimlerChrysler Corporation Power Train Engineering CIMS 482-01-07, 800 

Chrysler Drive Auburn Hills, MI 48236-2757 PH : (248) 576-4996; FX : (248) 576-2182; email: mjr8@daimlerchrysler.com

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

4b. Non-thermal Plasma R&D

5e. R&D on PM Reducing Technologies

Objective

• Develop an aftertreatment system that will achieve 90% NOx reduction using less than 5% of the 

engine power on a compression ignition direct injection (CIDI) engine. The program supports goals of 

the Partnership for a New Generation of Vehicles (PNGV). 

Approach 

• Synthesize and test new catalysts in simulated and real diesel exhaust. A highly active plasma catalyst 

is critical to meeting the program goals.

• Measure plasma catalyst activity in simulated and real diesel exhaust.

• Investigate the role of NO2 and other species (partial oxidation products and hydrocarbon radicals) on 

NOx reduction activity on select catalysts.

• Develop prototype reactors.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

70

• Evaluate prototype reactors for energy efficiency and durability.

• Measure the efficiency of plasma catalyst systems for particulate removal.

Accomplishments 

• New catalysts have been discovered that reduce NOx over a wider temperature window (150-400oC) 

when placed in or down-stream from a plasma reactor. The equivalent fuel penalty for NOx reduction 

is less than 5%.

• A catalyst combination resulted in reduced formation of formaldehyde and N2O (to negligible levels).

• Two sets of engine tests on a PNNL prototype plasma catalyst system were completed. Performance 

varied from as high as 55% NOx reduction to as low as 20% NOx reduction over the five vehicle test 

points.

• A new intermediate scale reactor was built and tested.

• Particulate removal (92-96%) using a packed bed plasma catalyst system was demonstrated over a 

range of EGR conditions.

• Complete nitrogen balance was obtained for the best catalysts and catalyst combinations.

• Designed and made new forming dies for fabricating the latest iteration of ceramic dielectric 

components for the experimental non-thermal plasma reactor.

• Initiated tests to establish a commercially viable ceramic component fabrication procedure using low 

temperature co-fired material from a commercial source and a high-temperature ceramic green tape 

produced in-house at ORNL.

Future Directions

• Continue to develop higher activity catalysts that are durable over long periods of time in a real diesel 

environment.

• Develop improved prototype plasma reactor system for engine testing in late 2001.

• Continue to probe mechanisms of NOx reduction over catalyst surfaces.

• Investigate ways to optimize both the NOx and particulate removal efficiency of plasma catalyst 

systems. 

Introduction

Previous work on this program showed that 

plasma-catalyst systems can reduce NOx emissions in 

simulated diesel exhaust; however, improvements in 

the efficiency and design of the plasma reactor 

systems, as well as in the efficiency of the catalysts, 

are necessary for vehicle applications. Research in 

FY00 had three primary foci: 1) evaluating plasma 

catalyst prototype systems on real engine exhaust, 2) 

improving catalyst and reactor efficiencies, and 3) 

revealing mechanisms that lead to NOx reduction 

using select catalysts. In addition, some scoping 

studies were performed to determine the extent of 

particulate removal possible with a plasma.

FY00 Results

Catalyst development efforts in FY2000 

focussed on completely characterizing the product 

distribution from catalyst B, which was discovered 

last year, and on synthesizing and evaluating new 

catalytic materials. A new catalyst, designated 

catalyst C, which has high NOx reduction activities 

over a temperature range that compliments the 

activity range of catalyst B was discovered. As 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

71

shown in Figure 1, this catalyst reduces 80-90% of 

NOx at temperatures ranging from 300-500o

C. When 

catalyst C is combined with catalyst B, a high NOx

conversion over temperatures ranging from 150-

500o

C can be achieved as illustrated in Figure 2. 

Small amounts of formaldehyde and minor amounts 

of N2O are formed as by-products of the NOx

reduction reaction over catalyst B. Combination of 

catalysts B and C results in reduction of 

formaldehyde formation. In addition, there is 

insignificant N2O formation over catalyst C (Figure 

2).

A prototype double dielectric barrier plasma 

reactor was tested for NOx reduction activity on 

exhaust from a 1996 1.9L Volkswagen TDI diesel 

engine. Catalyst B was coated onto 300 cell/inch 

cordierite monoliths provided by DaimlerChrysler 

Corporation and was placed downstream from the 

region in which the plasma was generated. Engine 

tests were performed at Oak Ridge National 

Laboratory. Certification diesel fuel with a sulfur 

level of 350 ppm was used for engine testing.

Figure 3 shows the NOx conversion at a universal 

engine test point where the conditions and exhaust 

gas concentrations are described in Tables 1 and 2. 

The total NOx conversion was measured by: 1.) a 

chemiluminescent NOx analyzer (NOx that does not 

show up as NO or NO2 is assumed to be reduced), 

and 2.) an FTIR (NOx that is not detected as N2O, 

NO2, NO or other nitrogen-containing species is 

assumed reduced to N2). The background value is 

the amount of NOx that was removed between the 

inlet and outlet of the device when no power is 

delivered to the plasma. This background may arise 

Figure 1. Thermal and Plasma Assisted NOx Conversion 

as a Function of Temperature for Catalyst C

Figure 2. NOx Conversion, N2O and Formaldehyde 

Formation as a Function of Temperature for 

Catalyst B Mixed with Catalyst C

Figure 3. NOx Reduction from Diesel Engine Exhaust for 

a 2-Stage Plasma Catalyst System with and 

without Added Propylene

Table 1. Engine Conditions

Revolutions per Minute (rpm) 1,900

Torque (ft-lb) 61

Horsepower (hp) 22

Air/Fuel Ratio 28

Airflow (scfm) 59-63

Fuel Flow (cc/sec) 1.3

Temperature into Device (o

C) 276-279

Temperature out of Device (o

C) 171-215
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

72

from thermal conversion, adsorption, or calibration 

differences between the inlet and outlet CLAs. There 

was a small amount of drift in the engine-out NOx

concentration during the testing period. Because the 

percent NOx conversion value depends on the initial 

NOx concentration, this drift was taken into account 

in the "corrected" FTIR value shown in Figure 3. It 

can be seen from Figure 3 that with no added 

hydrocarbon (engine out C1:NOx = 0.4:1) there is no 

significant reduction of NOx. When 870 ppm 

propylene (2610 ppm on a C1 basis) is added to the 

exhaust, 47-57% NOx reduction is measured. A 

minimum NOx reduction of 20% was observed at a 

test point with high space velocity (25,000 hr-1) and 

temperature (300o

C). 

The total hydrocarbon consisted of 140 ppm C1

from engine-out exhaust plus added propylene. The 

maximum NOx conversion was achieved at a C1:NOx

ratio of 6:1 with no additional benefit from 

increasing the ratio to 9:1. (Figure 4) This result is in 

good agreement with bench data on catalyst B which 

showed that maximum NOx conversion can be 

obtained at a C1:NOx ratio of 6. The power required 

to run the reactor was estimated from the wall plug 

power and was on the order of 15 J/L or 2.7% 

engine-out (0.6 HP). The combined impact on FTP 

fuel economy from the increased electrical load and 

the addition of HC reductant is estimated to be six 

percent at this stage of development.

Conclusions

PNNL and the LEP have developed plasma 

assisted catalyst systems that can reduce 70% NOx

over a large temperature range (150-500o

C) on 

simulated diesel exhaust. Engine tests on a first stage 

prototype system were successfully completed. The 

plasma assisted catalyst system achieved 20-57% 

NOx conversion depending on the engine conditions. 

List of Publications

1. M.L. Balmer, R.G. Tonkyn, G. Maupin, I. Yoon, 

A. Kolwaite, S. Barlow, N. Domingo, J.M. 

Storey, J. Hoard, and K. Howden, "Non-Thermal 

Plasma System Development for CIDI Exhaust 

Aftertreatment", SAE 2000-01-1601. 

2. J.W. Hoard, Evgenii Kalashnikov, Joseph Szente, 

and Diane Podsiadlik, "Cluster Formation by 

Barrier Discharge in Simulated Engine Exhaust 

Gas at High Temperature", Applied Physics 

Letters, vol. 76 no. 21, 22 May 2000.

3. M.L. Balmer, R.G. Tonkyn, I. Yoon, A. 

Kolwaite, S. Barlow, G. Maupin, and J. Hoard, 

"NOx Destruction Behavior of Select Materials 

when Combined with a Non-Thermal Plasma", 

SAE 1999-01-3640, October 1999.

4. M.L. Balmer, R.G. Tonkyn, I. Yoon, A. 

Kolwaite, S.Barlow, G. Maupin, and J. Hoard, 

"Diesel NOx Reduction Activity of Select 

Materials when Combined with a Plasma", 

Proceedings of the Diesel Engine Emissions 

Reduction Workshop, July 1999.

5. John Hoard, Leaf Worsley, and William Follmer 

(ASI), "Electrical Characterization of a 

Dielectric Barrier Discharge Plasma Device", 

SAE paper 1999-01-3635.

6. John Hoard and M. Lou Balmer (PNNL), 

"Plasma-Catalysis for Diesel NOx Remediation", 

Table 2. Engine-Out Exhaust Gas Concentrations

Oxygen 11%

Carbon Dioxide 7%

Carbon Monoxide 150 ppm

Hydrocarbon as C1 140 ppm

NOx 320 ppm

Figure 4. Percent NOx reduction as a function of the ratio 

of C1/NOx in the exhaust. Engine-out C1 was 

140 ppm and additional C1 was achieved with 

added propylene
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

73

Journal of Advanced Oxidation Technologies, 

December 1999.

7. John Hoard, Tim Wallington, James Ball, 

Michael Hurley, Ken Wodzisz, and M. Lou 

Balmer, "Role of Methyl Nitrate in Plasma 

Exhaust Treatment", Environmental Science and 

Technology, October 1999.

8. M. Lou Balmer, "Towards Clean Cars: Plasma 

Destruction of Vehicle Pollutants", PNNL/DOE 

Onsite Review, September 1, 1999. 

List of Presentations

1. Hoard, John; "Plasma-Catalyst for Diesel 

Emission Reduction", invited presentation for 

the 2000 International Chemical Congress of the 

Pacific Basin Societies, Symposium #211 

Plasma Chemistry and Technology for Green 

Manufacturing, Pollution Control, and 

Applications, Honolulu, HI, December 14-19, 

2000.

2. Balmer, M. Lou; Alexander Panov; Steven Yoon; 

Ana Kolwaite; and Russ Tonkyn; "Plasma 

Catalytic Lean NOx Reduction with Zeolite and 

Alumina Catalysts", 2000 National Laboratory 

Catalysis Research Conference (NLCAT 2000), 

Argonne, IL, October 12-13, 2000.

3. Hoard, John; "Plasma-Catalyst Aftertreatment 

for Lean Engine Exhaust", section in SAE Diesel 

Engine TOPTEC: Emissions Challenges for the 

Future, Indianapolis, IN, September 26-27, 2000.

4. Hoard, John; Paul Laing; M. Lou Balmer; and 

Russ Tonkyn; "Fuel Economy Impact of PlasmaCatalyst Versus Active Lean NOx

Aftertreatment", DOE Diesel Engine Emission 

Reduction Workshop, San Diego, CA, August 

2000.

5. Panov, Alexander; Steven Yoon; Ana Kolwaite; 

Russ Tonkyn; and M. Lou Balmer; "NOx

Reduction Behavior of Alumina and Zeolite 

Catalysts in Combination with a Non-Thermal 

Plasma", DEER 2000, San Diego, CA, August 

21-24, 2000.

6. Tonkyn, Russ; S. Barlow; Steven Yoon; 

Alexander Panov; Ana Kolwaite; and M. Lou 

Balmer; "Lean NOx Reduction by Plasma 

Assisted Catalysis", DEER 2000, San Diego, 

CA, August 21-24, 2000.

7. Yoon, Steven; Russ Tonkyn; Alexander Panov; 

Ana Kolwaite; S. Barlow; and M. Lou Balmer; 

"Reaction Mechanism Study of Lean NOx

Reduction using Plasma Catalysis", American 

Chemical Society, Washington, DC, August 20-

24, 2000.

8. Balmer, M. Lou; "Plasma Catalysts for NOx

Reduction", Invited Talk, GlobeEx 2000 

International Energy Conference, Las Vegas, NV, 

July 23-28, 2000.

9. Hoard, Bretz, and Bryzik (poster presentation 

made by Bryzik), "Non-Thermal Plasma 

Catalysts for NOx Destruction, Central Region 

ACS Meeting, Cincinnati, OH, May 16-19, 

2000.

10. Balmer, M.L.; R. Tonkyn; G. Maupin; I. Yoon; 

A. Kolwaite; S. Barlow; N. Domingo; J.M. 

Storey; J. Hoard; and K. Howden; "Non-Thermal 

Plasma System Development for CIDI Exhaust 

Aftertreatment", SAE 2000 FutureCar 

Conference, Arlington, VA, April 2-6, 2000.

11. M. Lou Balmer, "NOx Reduction of Select 

Materials When Combined with A Non-Thermal 

Plasma", Ford Motor Company, November 2, 

1999.

12. M. Lou Balmer, R. Tonkyn, S. Yoon, A. 

Kolwaite, S. Barlow, G. Maupin and T. Orlando, 

"NOx Reduction of Select Materials when 

Combined with a Non-Thermal Plasma", Society 

of Automotive Engineers, Fall Fuels and 

Lubricants Meeting, October 25-28, 1999, 

Toronto, Canada.

13. M. Lou Balmer, R. Tonkyn, S. Yoon, A. 

Kolwaite, S. Barlow, G. Maupin and T. Orlando 

"Diesel NOx Reduction Activity of Select 

Materials When Combined with a Plasma", 

Castine, ME, July 5-9, 1999.

14. John Hoard, Colleen Bryzik, and M. Lou 

Balmer, "Plasma-Catalysis for Lean NOx: 

Comparison of Two Catalysts", DOE Diesel 

Engine Emission Reduction Workshop, Castine, 

Maine, July 1999.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

74

15. John Hoard, "Plasma-Catalysis for Exhaust 

Aftertreatment in Lean Engines", MIT Engine 

and Fuels Consortium presentation, Auburn 

Hills, MI, March 1999.

List of Acronyms

C1 per carbon basis

CIDI Compression Ignition Direct 

Injection

CLA Chemiluminescent NOx Analyzer

CRADA Cooperative Research and 

Development Agreement

EGR Exhaust Gas Recirculation

FTIR Fourier Transform Infrared 

Spectrometry

HP Horsepower

J/L Joules/Liter

PNGV Partnership for the Next Generation 

of Vehicles

ppm parts per million
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

75

B. Sulfur-Tolerant NOx Adsorber System Development

John M. Storey (primary contact), Mike Kass 

Oak Ridge National Laboratory

P.O. Box 2009, MS 8087

Oak Ridge, TN 37831-8087

(423) 574-0574, fax: (423) 574-2102, email: storeyjm@ornl.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax: (202) 586-9811, e-mail: Kathi.Epping@hq.doe.gov

Subcontractor: GoalLine Environmental Technologies, Knoxville, TN

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

Tasks

4a. NOx Adsorber R&D

4e. R&D on NOx Reducing Technologies

Objectives

• Develop and construct prototype device for test on ORNL engine test stand.

• Develop a regeneration strategy.

• Carry out measurements of NOx control effectiveness and regeneration by-products in ORNL engine 

dyno lab.

Approach

• Subcontract to GoalLine Environmental Technologies to develop and construct a dual channel 

prototype NOx adsorber.

• Develop a reformer and regeneration strategy that would utilize diesel fuel to regenerate the prototype 

NOx adsorber.

• Installation of the prototype device on an engine test stand and measure NOx removal effectiveness 

and regeneration by-products at selected engine operating conditions.

Accomplishments

• Preliminary evaluation data on adsorber performance under controlled laboratory conditions were 

generated by GoalLine and provided to ORNL.

• A prototype sulfur trap-NOx adsorber system was developed and built by GoalLine for light-duty 

vehicle applications. This prototype was delivered to ORNL.

• The prototype system was installed on a light-duty engine test stand and an initial evaluation was 

completed.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

76

Future Directions

• Development and test of simpler and smaller devices based on the technology developed by GoalLine.

• Incorporation of diesel fuel reformer for regeneration.

• Additional work with sulfur traps to determine durability and sulfur fate.

Introduction

The proposed light-duty vehicle emission 

standards for 2007 require very low fleet average 

NOx emission levels (0.07 g/mile). However, most 

current NOx reduction systems are unable to meet the 

fleet average 2007 standards for full useful life 

certification. Of the current technologies being 

developed for NOx reduction from diesel engines, 

NOx adsorber technology offers very promising 

means of achieving the fleet average 2007 NOx

emission standards.

NOx adsorbers work on the principal of selected 

chemical adsorption. In a typical adsorber system 

NO and NO2 gas molecules are adsorbed on the 

surface until all the available sites are filled. When 

the surface becomes saturated, NOx is no longer 

removed from the gas stream. At this point, the 

adsorber is regenerated by flowing a reducing gas 

mixture over its surface. During regeneration, the 

NOx on the surface is reduced via three-way catalysis 

to molecular nitrogen (N2) which is released into the 

gas stream. Sulfur (in the form of SO2), however, 

also attaches to the adsorber surface and reduces the 

number of sites available for NOx pickup. 

Unfortunately, this sulfur is not removed during 

regeneration and the amount of sulfur increases on 

the surface as the adsorber ages. As a result, 

adsorber performance decreases with increased 

sulfur loading. 

Sulfur trap and NOx adsorber systems were 

developed by GoalLine Environmental Technologies 

and tested under controlled laboratory conditions. A 

prototype was developed and delivered to ORNL for 

engine evaluation. The ORNL experimental efforts 

have focused on measuring the removal of NOx

emitted from a light-duty engine and the 

characterization of the gas chemistry occurring 

during regeneration. 

Approach

GoalLine Environmental Technologies 

developed a NOx adsorber system that consists of a 

sulfur trap placed upstream of a NOx adsorber. The 

sulfur trap removes the gaseous sulfur, thereby 

preventing the NOx adsorber from becoming 

poisoned. This system was evaluated under 

controlled laboratory conditions and the performance 

of the sulfur trap and NOx adsorber during adsorption 

Figure 1. NOx capacity of GoalLine system as function of 

exhaust temperature.

Figure 2. Released NOx, SO2, and N2O gas 

concentrations during regeneration.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

77

and regeneration were characterized. These efforts 

led to the development of a prototype device which 

was sent to ORNL to be tested on a light-duty diesel 

engine. 

The NOx adsorber capacity was found to be 

temperature dependent as shown in Figure 1. The 

exhaust temperature was controlled through engine 

loading and the levels of NOx were measured using 

bench analytical equipment and FTIR spectroscopy. 

Regeneration was performed using a mixture of 10% 

hydrogen in nitrogen at a space velocity of 2000/h. 

During regeneration, NOx and N2O were 

immediately released into the gas stream; while SO2

was released after 40 seconds of regeneration (see 

Figure 2). The regenerated levels of SO2 and NOx

were also affected by the exhaust temperature. 

Regeneration at high temperature was observed to 

release more SO2 and NOx than at a lower 

temperature. Interestingly, the release of N2O is 

substantially higher at the lower temperatures. 

Earlier work with lean NOx catalysts has shown a 

similar tendency for N2O formation at low 

temperature. Restraining N2O formation will clearly 

need to be considered for future NOx adsorber 

development.

Conclusions

NOx adsorber systems incorporating sulfur traps 

offer a promising means of reducing NOx levels. 

This system has shown the potential to reduce NOx in 

the range of 90 to 95 percent, including emissions 

during regeneration. This level of performance 

should be sufficient to allow a diesel light-duty 

vehicle to meet the Tier 2 fleet average NOx standard.

The effect of fuel sulfur can be minimized with 

this system and it is expected that lower sulfur fuel 

will enable this technology even further. The sulfur 

released during regeneration is in the form of SO2

and not sulfate PM.

Currently, N2O emissions are in the range of 0.01 

to 0.1 g/mile, which is similar to typical spark 

ignition light-duty vehicles. The formation of N2O 

during regeneration will need to be investigated for 

future research efforts. This may result in changes in 

adsorber design or reductant chemistry.

List of Acronyms

FTIR Fourier Transform Infrared 

Spectrometry

NOx Oxides of nitrogen

ORNL Oak Ridge National Laboratory

SO2 Sulfur dioxide
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

78

C. Reduction of NOx Emissions for Lean-Burn Engine Technology

Timothy J. Gardner (Primary Contact)

Sandia National Laboratories

Catalytic and Porous Materials Department

P.O. Box 5800, MS 1349

Albuquerque, NM 87185

(505) 272-7621, fax: (505) 272-7336, e-mail: tjgardn@sandia.gov

Contractor: Sandia National Laboratories, Albuquerque, New Mexico

Prime Contract No.: DE-AC04-94AL85000

Ralph N. McGill

Oak Ridge National Laboratory

Engineering Technology Division, Power Systems Section 

P.O. Box 2009, MS 8087

Oak Ridge, TN 37831

(865) 574-4077, fax: (865) 574-2102, e-mail: mcgillrn@ornl.gov

Contractor: Oak Ridge National Laboratory, Oak Ridge, Tennessee

Prime Contract No.: DE-AC05-96OR22464

Kevin C. Ott

Los Alamos National Laboratory

Chemistry Division Actinides, Catalysis, and Separations Group, MS J514

Los Alamos, NM 87545

(505) 667-4600, fax: (505) 667-3314, e-mail: kcott@lanl.gov

Contractor: Los Alamos National Laboratory, Los Alamos, New Mexico

Prime Contract No.: W-7406-ENG-36

DOE Program Manager: Kathi Epping 

(202) 586-7425, fax (202) 586-9811 email: Kathi.Epping@ee.doe.gov

CRADA Partner: Low Emissions Technologies Research and Development Partnership (Member 

Companies: Ford Motor Company, General Motors, and DaimlerChrysler Corporation)

Michael J. Royce (Primary Contact) DaimlerChrysler Corporation Power Train Engineering CIMS 482-01-07, 800 

Chrysler Drive Auburn Hills, MI 48236-2757 PH : (248) 576-4996; FX : (248) 576-2182; email: mjr8@daimlerchrysler.com

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

Tasks

4a. NOx Adsorber R&D

Objectives

• Develop new catalyst technology to enable CIDI engines to meet EPA Tier 2 emission standards.

 Approach

• Development of new catalyst materials for reducing NOx emissions in lean-burn exhaust 

environments, including:
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

79

- Hydrous metal oxide-supported catalysts, and

- Zeolite-supported catalysts.

• Evaluation of new catalyst materials in both bulk powder and monolith forms, including short term 

durability testing, and testing of prototype catalytic converters on diesel engine dynamometers.

• Scale-up of synthesis and processing of promising catalyst formulations to enable fabrication of 

prototype catalytic converters for engine dynamometer testing.

• Technology transfer of most promising catalyst formulations and processes to LEP CRADA partners.

 Accomplishments

• LANL optimized several processing routes, metal ions, and supports for new Ferrierite (FER)-

supported metal catalysts. A provisional U.S. patent application was filed for these new catalyst 

materials, covering formulations, preparation procedures, and potential catalytic applications.

• Successfully adapted FER-supported metal catalyst synthesis procedures to prepare monolith core 

samples with similar high NOx reduction activity over a broad temperature range.

• LANL catalyst samples were transferred to LEP partners for compositional tests, as well as 

determination of the adsorption vs. catalysis functionality of these materials with respect to both NOx

and hydrocarbon species.

• Identified a unique water sensitivity associated with the new FER-supported metal catalysts. Further 

characterization is in progress.

• The LANL portion of this project was the winner of the 2000 National Laboratory CIDI R&D Award 

in recognition of outstanding achievement in research and development of lean NOx catalysts for CIDI 

emission control.

• The engine dynamometer test bed at ORNL was transitioned to a Mercedes 1.7 L diesel engine, which 

should be more representative of the engine-out emissions profile of the prototype PNGV vehicles. 

• Extensive microstructural characterization of SNL and LANL catalysts in powder or monolith core 

form was completed at ORNL.

• LANL and SNL examined short-term hydrothermal and SO2 aging issues with FER-supported metal 

catalysts and Pt-based/HMO catalysts, respectively.

• SNL completed characterization studies on lower light-off temperature and wider temperature window 

Pt-based catalysts for lean-burn NOx reduction via hydrocarbons.

• Two different phases of technology transfer activities involving SNL materials have now been 

completed, covering a minimum of three different Pt-based/HMO catalyst formulations. A defined 

process now exists for use in future technology transfer activities. 

• SNL completed fundamental studies aimed at a better explanation of the limitation of supported Pt 

catalysts for applications involving the lean-burn reduction of NOx via hydrocarbons.

 Future Directions

• Extend current national laboratory/LEP CRADAs into the FY01-03 time frame (all current CRADAs 

expire by 2/01). Address lean-burn NOx reduction catalyst options and research approaches within 

funding limitations. Continue SCR of NOx via hydrocarbons effort with promising new catalysts.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

80

• Retrofit of SNL NOx reduction reactor unit to support selective catalytic reduction testing capability 

with urea/ammonia reductant. Obtain benchmark urea/ammonia SCR catalyst formulations from 

catalyst suppliers.

• Begin catalyst development and testing efforts with SCR of NOx via ammonia, with initial emphasis 

on supported oxide catalysts and supported base metal catalysts. Goals are increased activity (> 90% 

at 200o

C @ 25,000 h-1), lower catalyst light-off (125-150oC), to understand ammonia storage issues on 

catalyst/washcoats, and to determine hydrocarbon influence on the SCR of NOx via ammonia process.

• Understand water adsorption issues associated with LANL FER-supported metal catalyst materials 

and attempt to solve these problems via alterations of the zeolite structures, frameworks, topologies, or 

surface chemistry.

• Complete designed experiment regarding optimization of FER-supported metal catalyst preparation, 

add complete data to provisional patent application, and file U.S. patent application in final form.

• Continue microstructural analysis of new LANL and SNL catalysts at ORNL.

• Determine the possible effects of particulate matter (PM) on the NOx reduction performance of leanburn NOx catalysts.

Introduction

This multi-partner effort has been continued 

under OAAT sponsorship and involves separate 

CRADAs between three national laboratories (Los 

Alamos National Laboratory [LANL], Oak Ridge 

National Laboratory [ORNL], and Sandia National 

Laboratories [SNL]) and the Low Emission 

Technologies Research and Development Partnership 

(LEP, composed of DaimlerChrysler Corporation, 

Ford Motor Company, and General Motors 

Corporation). These CRADAs are currently in their 

final year, although project extension into the 

FY2001-2003 time frame is planned. The project 

addresses reduction of CIDI engine NOx emissions 

using exhaust aftertreatment - identified as one of the 

key enabling technologies for CIDI engine success. 

The overall CRADA efforts are focused on the 

development and evaluation of new catalyst 

materials for reducing NOx emissions, specifically 

targeting the selection of appropriate catalyst 

materials to meet the exhaust aftertreatment needs of 

the PNGV vehicles.

With the new EPA Tier 2 emission standards 

scheduled to be in place starting in 2004, our 

program has now begun general redirection efforts to 

address new and potentially more efficient NOx

reduction options for lean-burn exhaust 

aftertreatment. This year we began program 

transition toward the selective catalytic reduction 

(SCR) of NOx by urea (or ammonia). Efforts related 

to SCR of NOx via hydrocarbons will continue as 

promising new catalysts are identified.

Los Alamos National Laboratory (LANL) 

Efforts

LANL’s work has focused on the development of 

new and stable zeolite-based catalysts for NOx

reduction in lean-burn exhaust environments. This 

work is complementary to the SNL work since these 

non-precious metal catalysts are typically active for 

NOx reduction at higher temperatures than those of 

the Pt-based catalysts under investigation at SNL. 

In FY1999, a new family of Ferrierite (FER) 

zeolite-supported non-precious metal catalysts that 

have both high apparent NOx reduction activity and a 

broad range of appreciable NOx conversion was 

discovered. Additional experiments then focused on 

the optimization of preparation procedures (both 

support pretreatment and metal addition) to enable 

reproducible FER-supported metal catalyst 

fabrication to support the filing of a provisional U.S. 

patent application. 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

81

In FY2000, the FER-supported metal catalyst 

synthesis procedures were successfully adapted to 

prepare monolith core samples with similar high 

apparent NOx reduction activity over a broad 

temperature range. Microstructural and 

compositional characterization of two different FER 

supports were performed at ORNL and General 

Motors, respectively, to aid overall characterization 

efforts. Short-term hydrothermal aging experiments 

at LANL indicated good catalyst stability at 

temperatures up to 750-850o

C, where some 

deterioration in high temperature catalyst 

performance was observed. Standard LANL test 

conditions included 20 min isothermal holds to 

achieve steady state in an overall temperature rampdown test mode.

Activity testing with these materials indicated a 

distinct possibility that the high apparent NOx

conversion included contributions from both NOx

adsorption, as well as SCR of NOx via hydrocarbons. 

An effort was therefore undertaken to determine the 

adsorption vs. catalysis functionality of these 

materials. Ford staff performed extensive transient 

tests with LANL catalyst samples to help understand 

these issues. Initial transient tests involved studying 

NOx adsorption capability by ramping up the catalyst 

temperature at a controlled rate (15o

C/min) using a 

gas mix consisting of 75 ppm NO, 12% O2, and 

balance N2. These experiments were run both with 

and without H2O (5%) in the feed. The results of this 

experiment are shown below in Figure 1. Since no 

hydrocarbon was used in these experiments, NOx

removal in this case would involve an adsorption 

process. In the absence of water (labeled as 0% 

H2O), nearly all of the NO fed to the sample is 

adsorbed up to a temperature of ~250o

C. Above 

250o

C, the NOx adsorption drops sharply and 

becomes negative, indicating NOx desorption from 

the sample. All of the NOx is desorbed from the 

sample by a temperature of 550o

C. Separate 

experiments determined that the NOx desorbs 

predominantly as NO2. As shown in Figure 1, the 

addition of 5% H2O to the feed almost completely 

destroys the NOx adsorption capacity of the sample. 

This indicates that NO does not effectively compete 

with H2O for adsorption sites on the catalyst.

An experiment similar to that shown in Figure 1 

was also performed in which 300 ppm of propylene 

(as C1) was added to the feed. In this case, at least 

some catalytic NOx removal would be expected due 

to the presence of the hydrocarbon. The results for 

these transient experiments are shown in Figure 2. 

Note that in this case apparent NOx conversion is 

plotted on the y axis; contributions from both 

adsorption and catalytic reaction are both included in 

this case. In the case of the feed without water 

(labeled Hydrocarbon with 0% H2O), the low 

temperature NOx profile is very similar to that 

observed in Figure 1. This indicates that it is highly 

likely that, even in the presence of the hydrocarbon, 

NOx is adsorbed on the catalyst under these 

Figure 1. Results showing the effect of water (H2O) on 

the NOx adsorption behavior of a LANL FERsupported metal catalyst

Figure 2. Results showing the effect of water (H2O) on 

the apparent NOx conversion profile of a 

LANL FER-supported metal catalyst
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

82

conditions. Above 300o

C, it is likely that NOx is 

converted via reaction with the hydrocarbon. 

Separate evidence under similar conditions indicates 

propylene also adsorbs on the FER-supported metal 

catalyst at low temperatures, with CO2 production 

beginning at 150o

C and peaking at ~450oC. This 

indicates that the active region of catalytic lean-burn 

NOx reduction is at temperatures > 250-300o

C. Other 

evidence generated at LANL indicates that this 

reaction may involve the nonselective production of 

nitrogen-containing hydrocarbons rather than 

selective catalytic reduction of NOx to N2. As in the 

case of Figure 1, the addition of water to the feed has 

a significant negative effect on the apparent NOx

conversion, including both the region of high NOx

adsorption (< 200o

C) and the region of NOx

conversion (> 250o

C).

 One of the interesting aspects of the Ford work 

was the discovery of the sensitivity of the FERsupported metal catalysts to H2O. Previous work at 

LANL using their standard temperature ramp-down 

test protocol with 20 min isothermal hold periods had 

not revealed a sensitivity of the catalysts to water in 

the feed. Additional work at LANL did reproduce 

the water sensitivity observed in the Ford tests, and 

the results of these experiments are shown below in 

Figure 3. The data in Figure 3 show that the 

temperature ramp-up test mode in the presence of 

H2O clearly produces the worst results, with the 

apparent NOx conversion at low temperature almost 

disappearing. In contrast, reasonable NOx

conversion is achieved using any of the other test 

protocols shown in Figure 3, either with or without 

the presence of water. By comparing the Ford and 

LANL test protocols, it is possible to conclude that 

the sensitivity of the FER-supported metal catalysts 

to water depends on the nature of their exposure. 

Catalyst exposure to water at low temperature 

(<400o

C), similar to the Ford test protocol, is 

extremely detrimental to catalyst performance. 

However, catalyst exposure to water at high 

temperature does not seem to significantly affect 

catalyst performance. Additional thermogravimetry 

studies at LANL showed that the water effect is 

reversible, but temperatures > 400o

C are required to 

remove the H2O from the FER structure. The low 

temperature water sensitivity of these materials will 

be a significant barrier to their use in emissions 

control devices, since alternate control strategies 

would need to be developed to minimize catalyst 

exposure to water at low temperatures (cold start, 

etc.).

Efforts are continuing to both further understand 

these water sensitivity issues, as well as trying to 

overcome them through changes in zeolite structure, 

topology, framework, and/or surface chemistry. 

Further automaker reactor testing is planned if less 

water-sensitive zeolite-based catalysts can be 

developed at LANL. 

This project was the winner of the 2000 National 

Laboratory CIDI R&D Award in recognition of 

outstanding achievement in research and 

development of lean NOx catalysts for CIDI emission 

control.

Oak Ridge National Laboratory (ORNL) 

Efforts

ORNL’s continuing role in this project has been 

to provide characterization of catalyst performance, 

both in bench scale reactor testing and in an engine 

laboratory, in addition to microstructure 

characterization of catalysts using electron 

microscopy. 

Over the last few years, at the suggestions of the 

industry partner team, the test bed has been 

Figure 3. Results showing the effect of testing protocol 

on the NOx conversion observed with a LANL 

FER-supported metal catalyst. All data were 

collected after 20 min isothermal hold times at 

each temperature.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

83

transitioned from the larger 7.3 L Navistar diesel 

engine to the 1.9 L Volkswagen (VW) TDI diesel 

engine and most recently to the Mercedes 1.7 L 

diesel engine. The engine-out emissions profile of 

this new engine is more representative of the 

conditions that will exist in the prototype PNGV 

vehicles. Figure 4 shows the Mercedes 1.7 L diesel 

engine test bed in the ORNL engine laboratory.

 Over the last year, microstructural 

characterization was performed on several SNL and 

LANL catalysts (in both powder and monolith core 

form) at the High Temperature Materials Laboratory 

at ORNL. For the SNL materials, the nature, 

location, and morphology of additive phases to Ptbased/HTO:Si catalysts were examined, while the 

effect of support pretreatment procedures on the 

chemical composition and morphology of the LANL 

FER materials was also determined. To date, no 

conclusions can be drawn regarding microscopy of 

LANL catalysts in powder form versus catalytic 

activity measured on bench flow reactors. The 

outstanding electron microscopy facilities at ORNL 

continue to provide high quality service to the 

national laboratories as well as our CRADA partners. 

Previous work with the VW 1.9 L TDI diesel 

engine determined that particulate matter (PM) 

emissions from this engine might be affecting 

catalyst performance. Higher PM emissions might 

be expected for this engine since the exhaust gas 

recirculation (EGR) mode was active for all test 

conditions. Experiments are in progress to compare 

the emissions profile of the Mercedes and VW TDI 

engines. The interaction between PM emissions and 

the NOx reduction performance of lean-burn NOx

catalysts (either SCR via hydrocarbons or urea/

ammonia) will continue to be investigated in the 

future.

Sandia National Laboratories (SNL) Efforts

Technology transfer efforts with the SNL Ptbased/HMO catalysts were completed in the past 

year. The sum total of these efforts involved the 

transfer of a minimum of three different Pt-based/

HMO catalyst formulations, including recent work 

with respect to special additives to Pt/HTO:Si 

catalysts that both lower light-off temperature and 

broaden the temperature window of appreciable NOx

conversion. In general, it can be summarized that a 

significant breakthrough regarding lean NOx

catalysis was not achieved with the SNL materials 

and process, although this result is more a function of 

the extremely aggressive EPA Tier 2 emissions 

standards than the specific attributes of Pt-based/

HMO or other supported Pt catalysts. Significant 

benefits achieved by the technology transfer process 

were that these efforts added to the catalytic 

materials knowledge base and provided new insight, 

as well as providing a potential payoff with other 

catalyst materials and/or applications. Importantly, a 

process now exists for future technology transfer of 

Figure 4. Mercedes 1.7 L diesel engine mounted on the 

engine dynamometer test bed at Oak Ridge 

National Laboratory

Species New Mix Old Mix

NOx 75 250

Total HC (ppm as C1) 600 2100

n-C8H18 (ppm as C1) 450 525 (C3H8)

C3H6 (ppm as C1) 150 1675

Total HC (as C1): NOx 8:1 8.4:1

Total C3H6 (as C1): NOx 2:1 6:1

CO (ppm) 600 400

H2 (ppm) 200 133

CO2 (%) 5.0 7.0

O2 (%) 12 8

H2O (%) 5.0 8.0

SO2 (ppm) 1.5 15

Space Velocity (cc/cc*h-1) 25,000 50,000

Table 1. Comparison of old and new mix simulated 

exhaust gas formulations representative of 

lean-burn gasoline and small displacement 

(1.1-1.5 L) CIDI engine exhaust, respectively.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

84

LEP CRADA-developed catalyst formulations from 

the national laboratories to the LEP and their 

designated catalyst suppliers.

In response to FY1999 Peer Review Panel 

comments, fundamental studies related to the 

selective catalytic reduction of NOx over supported 

Pt catalyst materials were conducted in an effort to 

better explain the limitations of these materials for 

selective catalytic reduction of NOx via hydrocarbon 

reductants. Using a Pt/HTO:Si catalyst in monolith 

core form, we performed a series of experiments that 

isolated the effects of several key process variable 

differences between simulated exhaust gas 

formulations referred to as the old mix (lean burn 

gasoline) and new mix (small displacement CIDI 

engine). Table 1 shows the composition and process 

variable differences between the old mix and new 

mix simulated exhaust gas formulations. The new 

mix is based on averaged and weighted CIDI engine 

speed/load points typical of light-duty operation. 

The key differences between these formulations are 

the NOx concentration, the propylene (C3H6):NOx

ratio, and the space velocity, all of which are 

significantly lower for the new mix relative to the old 

mix. These key differences are highlighted in Table 

1.

Figure 5 shows the conversion profiles for the 

hydrocarbon (propylene and propane), CO, and NOx

species using the old mix test conditions with a 

typical Pt/HTO:Si catalyst. One important feature 

illustrated by Figure 5 is the strong coupling of the 

propylene oxidation and NOx reduction profiles, 

indicating the dominance of propylene as a reductant 

for NOx conversion. Relative to propylene, almost 

no conversion of NOx is observed in conjunction 

with either CO oxidation or propane oxidation. It 

would therefore be expected that process variable 

changes which retard or enhance the propylene 

oxidation reaction will similarly affect the NOx

reduction efficiency. Another important feature of 

Figure 5 is that although NOx conversion is 

reasonable for the old mix formulation (~60%), 

values in excess of 85% are required to meet Tier 2 

emission standards.

The cumulative effect of altering the variables 

described above (see annotated text in Figure 5) is to 

significantly reduce the maximum NOx conversion 

and to shift the location of the temperature of 

maximum NOx conversion to a much lower 

temperature, as indicated by the arrows 

superimposed on the NOx conversion profile in 

Figure 5, with the propylene:NOx ratio having the 

most significant effect. This cumulative effect is 

directly shown in Figure 6, which compares the NOx

and propylene conversion profiles for the old vs. new 

mix conditions. In addition to the propylene 

Figure 5. Typical conversion profiles for species of 

interest using the old mix test conditions with a 

supported Pt catalyst. The effect of altering 

each of the variables noted on the Figure is 

illustrated by the corresponding arrows.

Figure 6. Typical NOx and dominant hydrocarbon 

conversion profiles for species of interest in 

old vs. new mix formulations for a supported 

Pt catalyst. Note that the profiles 

representative of the new mix test conditions 

also include an n-octane oxidation profile (x 

symbols), in addition to both the propylene 

oxidation and NOx reduction profiles.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

85

oxidation and NOx reduction profiles, an n-octane 

oxidation profile is also shown for comparison in the 

case of the new mix formulation. It is obvious, 

however, that n-octane is not effectively utilized by 

the supported Pt catalyst for NOx reduction, even 

though it is present in the new mix formulation at a 

level three times higher than the propylene (see Table 

1). N-octane has only been shown to be an efficient 

reductant for NOx conversion over supported Pt 

catalysts at very high concentrations (~16:1 HC:NOx

ratio on a C1 basis), which are unacceptable due to 

fuel penalty considerations. 

In the case of the new mix results shown in 

Figure 6, the dominating effect of the low C3H6:NOx

ratio results in very low maximum NOx conversion 

(~20%). The combined effects of the lower space 

velocity, the lower feed NOx concentration, and the 

lower C3H6:NOx ratio also significantly shift the 

temperature of maximum NOx conversion to lower 

temperature. An additional concern associated with 

lowering the temperature of maximum NOx

conversion is that the selectivity of N2 production (as 

a result of NOx reduction) decreases as the 

temperature of maximum NOx conversion is 

lowered, with significant amounts of N2O being 

produced under these conditions. These overall 

results show that the activity of supported Pt 

catalysts in lean-burn NOx reduction by 

hydrocarbons is limited by both the type and quantity 

of hydrocarbon reductant. Small alkenes represent 

the most effective hydrocarbon reductants and onboard strategies for storage and/or production of 

these species, coupled with their delivery to the 

exhaust stream and catalytic converter unit, still 

should be considered feasible. However, few (if any) 

supported Pt catalyst systems utilizing reasonable 

quantities of hydrocarbon reductants have 

demonstrated the level of NOx reduction necessary to 

meet the Tier 2 emission standards. This fact makes 

it unlikely that supported Pt catalysts used in the 

selective catalytic reduction of NOx via hydrocarbons 

can be the sole solution to the emissions control 

needs of CIDI engines. Even with these limitations, 

one can easily envision a multicomponent emissions 

control scheme where these materials and catalytic 

processes can play an important role.

Sandia has also been involved in significant 

program redirection efforts toward utilizing catalytic 

processes involving the selective catalytic reduction 

of NOx by urea (or ammonia) for CIDI emissions 

control applications. These processes show great 

promise of achieving the levels of NOx conversion 

required to meet the Tier 2 emission standards. In 

FY2000, a gas phase FTIR spectrometer system for 

accurate determination of a wide variety of nitrogencontaining species was integrated into our existing 

NOx reduction reactor unit. This reactor unit has also 

been modified to accommodate an ammonia 

reductant feed and development efforts related to 

catalyst materials for selective catalytic NOx

reduction via ammonia have been initiated. Catalyst 

screening activities utilizing the reactor test unit 

should begin in the fourth quarter of FY2000.

List of Presentations

1. T. J. Gardner, R. N. McGill, and K. C. Ott, 

"Reduction of NOx Emissions for Lean-Burn 

Engine Technology," Presentation at the DOE 

CIDI Engine Combustion, Emission Control, and 

Fuels R&D Review, Argonne, IL, May 22, 2000.

2. R. N. McGill and J. M. Storey, "Engine and 

Emission Control Enablers for High Efficiency 

Light-Duty CIDI Engines." Presented at 

ENERGEX2000 - The Eighth International 

Energy Forum, Las Vegas, NV, July 25, 2000. 

3. T. J. Gardner and D. L. Mowery, "Challenges in 

Lean-Burn Automotive Exhaust Catalysis," 

Presented at ENERGEX2000 - The Eighth 

International Energy Forum, Las Vegas, NV, July 

25, 2000. 

List of Patents

1. K. C. Ott, N. C. Clark, and M. T. Paffett, 

"Catalyst and Process for Preparation of 

Catalysts for Lean Burn Engine Exhaust 

Abatement", Provisional U. S. Patent 

Application, Serial No. 60/162,431, October 28, 

1999.

List of Awards

1. Kevin Ott, Noline Clark, and Jon Ran of Los 

Alamos National Laboratory received the 2000 

National Laboratory CIDI R&D Award in 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

86

recognition of outstanding achievement in 

research and development of NOx catalysts for 

CIDI Engine Emission Control.

List of Acronyms

o

C Degrees Centigrade

C1 Unit Carbon Basis

C3H6 Propylene

C3H8 Propane

cc Cubic Centimeter

CO Carbon Monoxide

CIDI Compression Ignition Direct 

Injection

CRADA Cooperative Research and 

Development Agreement

EGR Exhaust Gas Recirculation

EPA Environmental Protection Agency

FER Ferrierite

FTIR Fourier Transform-Infrared 

FY Fiscal Year

HC Hydrocarbon

HMO Hydrous Metal Oxide

HTO:Si Silica-Doped Hydrous Titanium 

Oxide

L Liter

LANL Los Alamos National Laboratory

LEP Low Emissions Technologies 

Research and Development 

Partnership

min Minutes

n-C8H18 Normal Octane

NOx Nitrogen Oxides (NO and NO2)

ORNL Oak Ridge National Laboratory

PM Particulate Matter

PNGV Partnership for a New Generation of 

Vehicles

ppm parts per million (volume basis)

R&D Research and Development

SNL Sandia National Laboratories

TDI Turbo Direct Injection

VW Volkswagen
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

87

V. EXHAUST GAS PARTICULATE EMISSION CONTROL R&D

A. Optical Diagnostic Development for Exhaust Particulate Matter 

Measurements

Peter O. Witze (primary contact) and Robert M. Green

Combustion Research Facility

Sandia National Laboratories

PO Box 969, MS 9053

Livermore, CA 94550-0969

(925) 294-2691, fax: (925) 294-1004, e-mail: witze@sandia.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax: (202) 586-9811, e-mail: Kathi.Epping@ee.doe.gov

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

B. PM Emissions

Tasks

2. Sensors and Controls

Objectives

• Develop real-time, engine-out particulate matter (PM) diagnostics for measuring size, number density 

and volume fraction.

• Transfer resulting technology to industry.

Approach

• Simultaneous measurements of laser-induced incandescence (LII) and laser elastic scattering (LES) 

are used to obtain the following PM aggregate parameters using the Rayleigh-Debye-Gans 

polydisperse fractal aggregate (RDG-PFA) approximation:

- particle volume fraction;

- diameter of primary particles;

- number density of primary particles;

- geometric mean of the number of primary particles per aggregate;

- geometric standard deviation of the number of primary particles per aggregate; and

- mass fractal dimension - radius of gyration of the aggregated primary particles.

• Laser-induced vaporization with Laser Elastic Scattering (LIVES) is used to measure the soluble 

organic fraction (SOF) of the PM.

• Off-the-shelf components are used to build a measurement system that can be easily duplicated by 

industry partners.

• Artium Technologies Inc. of Los Altos Hills, CA will commercialize the resulting technology.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

88

Accomplishments

• LII signals have been characterized in a propane diffusion flame.

• Mini-dilution tunnel is operational on a 1.9 liter TDI diesel engine.

• LII-LES optical cell and data acquisition system is operational.

• Scanning mobility particle sizer (SMPS) for LII-LES calibration is operational.

• Initial phase of an LII-LES model has been completed.

• Real-time LII measurements of PM volume fraction have been demonstrated for engine startup, EGR 

and throttle transients.

• LIVES has been demonstrated for the real-time measurement of PM volume reduction in a diffusion 

flame.

Future Directions

• Complete LII-LES calibration/characterization with the SMPS.

• Improve the laser-heating/vaporization submodel in the LII-LES model.

• Develop LIVES as a technique for distinguishing SOF from solid-phase carbon.

• Develop experimental and modeling capability for RDG-PFA approximation for aggregate 

characterization.

• Apply the LII-LES and LIVES techniques to diesel exhaust.

Introduction

LII is a well-established technique for the 

measurement of PM volume fraction and primary 

particle size; it has been applied to both stationary 

burner flames and diesel engine combustion. Light 

from a high-energy pulsed laser is used to quickly 

heat the PM to its vaporization point, resulting in 

gray-body radiation that is proportional to the PM 

volume fraction; the cooling rate of the PM 

following laser heating is a measure of primary 

particle size. Simultaneous measurement of LES 

from the particles at several discrete angles relative 

to the incident laser beam can be used to obtain 

additional information regarding the characteristics 

of PM aggregates using the RDG-PFA 

approximation.

The advantages of LII-LES over conventional 

PM measurement techniques are that it can be 

applied in any environment (e.g., hot or cold, 

undiluted or diluted, etc.), it responds in real time, 

and is very sensitive to low PM concentrations 

(lower limit is estimated to be one part per trillion).

Approach

A schematic of the LII-LES experimental setup 

is shown in Figure 1. The second harmonic output of 

a Nd:YAG laser at 532 nm is used for excitation. The 

laser fluence is controlled using a half wave plate 

(HWP) and thin film polarizer (TFP). Three 

measurements are simultaneously obtained with fast 

photodetectors: 1) Incident temporal profile of the 

Figure 1. Schematic of the LII-LES experimental setup.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

89

laser pulse, detected from diffuse scattering through 

a neutral density filter (NDF); 2) LII signal, detected 

through a long-wave pass filter with a 570 nm cutoff; 

and 3) LES, detected through an NDF and an 

interference bandpass filter (BPF) centered at 532 

nm. A photograph of the actual hardware is presented 

in Figure 2.

The exhaust sampling and dilution configuration 

are illustrated schematically in Figure 3. The engine 

exhaust was sampled approximately 0.3 m 

downstream of the muffler using a tube with the 

entrance oriented upstream to the flow direction. The 

tube provided a flow of exhaust gas through a sample 

line heated to 100o

C to an ejector-pump diluter where 

the sample was diluted with heated, dry nitrogen at a 

nominal dilution ratio of 10. Upon exiting the diluter, 

the sample passed into both the optical cell where the 

LII and LES measurements were carried out, and the 

SMPS where the PM characteristics were also 

measured.

Results

Shown in Figure 4 are LII intensity 

measurements made during engine startup to 

demonstrate the real-time capabilities of LII. For 

these preliminary results the LII was not calibrated, 

but because it responds explicitly to PM volume 

fraction, the relative magnitudes of the 

measurements are quantitative. 

As mentioned earlier, LII is employed in a 

regime where laser energy heats the carbon PM to its 

vaporization point. Ideally, the laser energy is limited 

so there is negligible mass loss from the PM. 

However, because our data acquisition system is very 

fast, it is interesting to observe the LES signal at high 

laser fluences where there is measurable carbon mass 

loss. The long-dash curve shown in Figure 5 is the 

temporal profile of the incident laser intensity; the 

short-dash curve is the temporal profile of the LES. 

These curves have been normalized by their maxima, 

so that the difference in the two waveforms is the 

Figure 2. Exhaust-port optical cell and laser-beam 

conditioning optics.

Figure 3. Schematic Diagram of the Exhaust-Sampling 

System Illustrating the Engine, EjectorType diluter, optical cell, and the SMPS.

Figure 4. Preliminary LII measurements obtained during 

engine startup.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

90

direct result of mass loss from laser-induced 

vaporization (LIV). By assuming that the LES is in 

the Rayleigh regime, where the scattering is 

proportional to the particle diameter to the sixth 

power, the temporal change in volume reduction can 

be calculated, as indicated by the solid curve. While 

these LIVES measurements were obtained in a 

propane diffusion flame, it is apparent that a similar 

behavior could be observed in diesel exhaust at much 

lower laser fluences due to the vaporization of SOF. 

We plan to fully explore this possibility for a realtime diagnostic for PM composition.

Conclusions

We have demonstrated the real-time 

measurement capability of LII, and obtained 

preliminary measurements suggesting that LIVES 

may be a very useful tool for measuring the SOF of 

diesel PM. We have shown that LII measures the 

carbon volume fraction in the diesel exhaust, 

whereas a SMPS measures the total PM, including 

the SOF, and LES measures something in-between 

(Witze and Green). We have also shown that at high 

laser fluences the LII signal becomes weak (Witze et 

al.); theory does not explain this behavior (Kayes et 

al.), implying that there is something about the 

fundamental physics of the rapid heating of small 

particles that is not understood. This is an issue we 

hope to resolve through fundamental particle-heating 

experiments.

List of Publications

1. Kayes, D., Michelsen, H. A., Hochgreb, S. and 

Witze, P. O., "Limitations of the Laser-Induced 

Incandescence Model for Predicting LII Signals 

and Particle Sizes," in preparation. 

2. Witze, P. O., "Measurement of Particulate-Matter 

Size and Volume Fraction Using Laser-Induced 

Incandescence and Rayleigh Scattering," 

Proceedings of the American Chemical Society 

219th National Meeting, San Francisco, March 

26-31, 2000.

3. Witze, P. O. and Green, R. M., "Laser-Induced 

Incandescence and Elastic-Scattering 

Measurements of Particulate-Matter Volume 

Fraction Changes during Passage through a 

Dilution Tunnel", to be published in the 

Proceedings of the 10th International 

Symposium on Applications of Laser Techniques 

to Fluid Mechanics, Lisbon, July 2000. 

4. Witze, P. O., Kayes, D., Hochgreb, S., and 

Shaddix, C. R., "Time-Resolved Laser-Induced 

Incandescence and Laser Elastic Scattering 

Measurements in a Propane Diffusion Flame," 

submitted to Applied Optics. 

List of Presentations

1. Witze, P. O., "Measurements of Particulate 

Matter," DOE GDI Working Group Meeting, 

Livermore, January 18, 2000.

2. Witze, P. O., "Measurements of Particulate 

Matter," DOE CIDI Working Group Meeting, 

Livermore, January 20, 2000.

3. Witze, P. O., "Measurement of Particulate-Matter 

Size and Volume Fraction Using Laser-Induced 

Incandescence and Rayleigh Scattering," 

Proceedings of the 219th American Chemical 

Society National Meeting, San Francisco, March 

26-31, 2000.

4. Witze, P. O., "LII Measurements of Diesel 

Exhaust Particulate Matter," CIDI Engine 

Combustion, Emission Control, and Fuels 

Review, Argonne, May 22-24, 2000. 

List of Acronyms

LES Laser Elastic Scattering

LII Laser-Induced Incandescence 

Figure 5. Time-resolved, LIV volume reduction of 

carbon particles in a propane diffusion 

flame
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

91

LIVES Laser-Induced Vaporization with 

Elastic Scattering

PM Particulate Matter

RDG-PFA Rayleigh-Debye-Gans Polydisperse 

Fractal Agglomerate

SMPS Scanning Mobility Particle Sizer

SOF soluble organic fraction 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

92

B. Diesel Particle Scatterometer

Arlon Hunt (Primary Contact), Ian Shepherd, and John Storey

Lawrence Berkeley National Laboratory

70-108 University of California

Berkeley, CA 94720

(510) 486-5370, fax (510) 486-7303, e-mail: ajhunt@lbl.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax: (202)-586-9811, e-mail: Kathi.Epping@hq.doe.gov

ORNL Contact: John Storey

(865) 574-0574, fax: (865) 574-2102, e-mail: storeyjm@ornl.gov

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

B. PM Emissions

Tasks

2. Sensors and Controls

 Objectives

• Develop the Diesel Particle Scatterometer (DPS) for real-time diesel particle size measurements.

• Use the instrument to study particle characteristics as a function of engine type, load, RPM, fuel 

composition, and post-combustion processes (aftertreatment, dilution, etc.).

• Extend DPS capabilities in time, sensitivity, and application.

Approach

• Measure angle-dependent polarized light scattering from diesel exhaust, including the scattering 

intensity (millisecond response) and polarization transformations.

• Determine size distribution and the refractive and absorptive properties (n, k) of soot by comparing 

measured data with modeled scattering.

• Model soot scattering as: spheres - Mie scattering theory to fit data, agglomerates -represent clusters as 

coupled dipoles.

Accomplishments

• Installed and used two DPS instruments for real-time particle size measurements.

• Upgraded DPS hardware and software.

• Developed high-speed mode to follow rapid variations of particle loading.

• Used DPS to measure effectiveness of diesel afterburner and study engine cycling.

• Contacted instrument companies to begin commercialization of the DPS.

Future Directions

• Apply DPS to specific issues including engine type, operation, and fuel effects.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

93

• Study performance of aftertreatment devices and exhaust dilution effects.

• Extend instrumental and software capabilities.

• Carry out DPS commercialization through tech transfer.

• Dialogue with California agencies.

 Introduction

Particulate emissions from diesel engines are of 

increasing importance to regulatory agencies and to 

the public at large. Until now there has been very 

little real-time instrumentation to characterize diesel 

particulates as to their size distribution, composition, 

or morphology and almost no way to obtain 

meaningful measurements of engine emissions 

during transients. It has become clear that overall 

engine emissions in diesel engines are dependent on 

engine design, operation, and a trade-off between 

NOx and particulates. The NOx/PM trade-off is 

particularly relevant to determining the optimum 

EGR rates. We are developing and testing a new 

instrument, the Diesel Particle Scatterometer (DPS) 

for real-time diesel particle size and property 

measurements. We have designed, built and 

compared the DPS with other instruments and 

techniques for measuring diesel particulates. 

Presently we are operating two instruments, one at 

LBNL and one at ORNL. Figure 1 shows a 

photograph of the DPS. We are using the instruments 

to study how particle characteristics change with 

engine design, operation, fuel composition, and the 

effect of aftertreatment devices and dilution effects.

Approach

To characterize the diesel particles we measure 

angle-dependent polarized light scattering from 

diesel exhaust when illuminated with modulated 

laser light. In particular, the DPS measures both the 

scattering intensity and certain polarization 

transformations (matrix elements) of the incident to 

scattered laser light. The matrix elements are 

determined by the synchronous detection of the 

polarized light that is modulated at a 50 kHz rate by 

the polarization modulator and by the total scattered 

light. The detector output is digitized and analyzed 

by the software developed for the instrument. The 

three angle-dependent matrix elements are plotted on 

the computer monitor and are fit by modeled 

calculations using a Levenburg-Marquardt 

optimization program. The result is plotted as a size 

distribution and refractive and absorptive optical 

properties of the particles. The absorptive 

component of the index of refraction gives a measure 

of the graphic carbon content of the exhaust particles. 

An important advantage of the instrument is the rapid 

response time; it has been tested at greater than 1 Hz 

data acquisition rate. This speed allows for the 

measurement of engine transients and even cylinderto-cylinder to variations. 

Results

We have installed and used two DPS instruments 

for real-time particle size and property 

measurements. This year we upgraded the software 

and installed additional detectors to improve the 

performance of the instrument. In addition to its 

normal operation discussed in last year’s report, we 

have also used a new, high-speed data acquisition 

mode to follow cylinder-to-cylinder variations of 

particle loading. 

Figure 2 illustrates the sub-millisecond time 

response of the DPS to the exhaust generated at 

different exhaust gas recirculation (EGR) rates by a 

four-cylinder Volkswagen TDI engine operated at 

ORNL at a range of EGR rates. The total time shown 

Figure 1. Diesel Particulate Scatterometer
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

94

for each graph is about 100 milliseconds. These 

measurements show the dramatic increase in particle 

loading with a small change in EGR rate and 

indicates that it may be possible to develop a very 

sensitive EGR control sensor based on the current 

instrument.

A further set of tests on this engine demonstrates 

the ability of the DPS in its high speed data 

acquisition mode to resolve particle loading variation 

due to changes in engine speed and load. Figure 3 

shows the time variation of light scattering intensity 

during the test. Note the sharp transient when the 

running conditions change from idle to cruise.

The DPS was also used to determine the 

effectiveness of a prototype diesel afterburner being 

developed by Grahn Industries of Palo Alto, 

California. Figure 4 presents the change in particle 

size during this test and demonstrates the burn-out of 

the soot particles achieved in the afterburner.

Instrument companies have been contacted to 

determine their interest in commercialization of the 

DPS and copyright and patent applications have been 

submitted. A brochure package created by the LBNL 

Technology Transfer Department has been 

distributed to over 400 businesses/organizations and 

responses to the brochure are now accumulating.

Collaborations continue with: Prof. R. Dibble at 

the U.C. Berkeley Engine Laboratory (alternative 

fuels); Dr. R. Manliev of the Illinois Institute of 

Technology (instrument calibration); and Prof. P. 

Hull of Tennessee State University (particulate 

modeling with neural nets and coupled dipole 

model).

Figure 2. Particle Loading at Two EGR Rates (One 

Engine Cycle, VW TDI CIDI Engine)

Figure 3. DPS Response at Three Engine Operating 

Conditions

Figure 4. Particle Mean Radius as a Function of 

Afterburner Temperature
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

95

Conclusions

The DPS was upgraded by the addition of new 

detectors and the incorporation of improved data 

acquisition and analysis software. A high-speed data 

acquisition mode was developed to follow rapid 

changes in particle loading to resolve cylinder-tocylinder variations. Successful measurements of the 

effects of EGR rate and engine load and speed on 

particulate loading were conducted in a VW-TDI 

engine. A possible EGR control sensor based on the 

current instrument was identified. The DPS was also 

used to determine the effectiveness of a prototype 

Diesel exhaust afterburner in reducing particulate 

emissions. Instrument companies were contacted for 

commercialization of the DPS.

List of Publications 

1. A.J. Hunt, I.G. Shepherd, and J. M. Storey, 

"Rapid, In Situ Characterization of Diesel 

Particulates," Windsor Workshop on 

Transportation Fuels, Toronto, Ontario, Canada, 

June, 1999.

2. A.J. Hunt, I.G. Shepherd, and J. M. Storey, 

"Diesel Particle Scatterometer," DOE CIDI 

Engine Combustion, Emission Control, and 

Fuels Review, Argonne National Laboratory, 

May, 2000.

List of Acronyms

DPS Diesel Particulate Scatterometer

EGR Exhaust Gas Recirculation

LBNL Lawrence Berkeley National 

Laboratory

NOx Oxides of Nitrogen

ORNL Oak Ridge National Laboratory

RPM Revolutions per Minute

TDI Turbocharged Direct Injection
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

96

C. The Effect of Injector and In-Cylinder Conditions on Soot Formation in CIDI 

Engines

Dennis L. Siebers

Sandia National Laboratories

P.O. Box 969, MS 9053

Livermore, CA 94551-9053

(925) 294-2078, fax: (925) 294-1004, e-mail: siebers@sandia.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax: (202) 586-9811, e-mail: Kathi.Epping@hq.doe.gov

DOE Program Manager: Gurpreet Singh

(202) 586-2333, fax: (202) 586-4166, e-mail: Gurpreet.Singh@ee.doe.gov

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

A. NOx Emissions

B. PM Emissions

Tasks

1a. Advanced Fuel Systems

Objectives

• Investigate the effects of engine and injector parameters on soot formation in direct-injection (DI) 

diesel sprays:

- determine the effects of engine and injector conditions on DI diesel spray lift-off length, a key 

parameter in the soot formation process.

- provide a database for validating combustion and soot models in the multidimensional, 

computational models being developed for diesel engine design and optimization. 

Approach

• Utilize advanced optical diagnostics coupled with a unique optically-accessible diesel combustion 

simulation facility to conduct these investigations.

- Develop a natural light emission technique for measuring flame lift-off location.

- Measure flame lift-off length with natural light emission technique determined to be the best for 

locating the flame lift-off.

- Conduct experiments over a wide range of conditions, including those in current as well as 

proposed advanced diesel engines.

Accomplishments

• Began development of a comprehensive database on the effects of in-cylinder engine and injector 

conditions on diesel spray lift-off length. 

• Showed how changes in engine and injector parameters made to meet emissions regulations have 

changed the diesel combustion process. Results are providing insight on how future changes in these 

parameters will affect the diesel combustion and emissions processes.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

97

• Developed an OH chemiluminescence technique for measuring flame lift-off length on DI diesel 

sprays.

• Upgraded laboratory computer control, data acquisition, and gas supply systems and hardware.

Future Directions

• Complete lift-off length measurements. These measurements will provide the framework needed for 

interpreting and understanding the direct measurements of the soot formation process to be made next.

• Make quantitative measurements of the effects of in-cylinder engine and injector conditions (including 

EGR) on soot formation.

• Investigate wall impingement effects on the evolution of diesel combustion and emissions processes.

• Investigate injection rate modulation effects on diesel combustion and emissions. 

Introduction

There is growing evidence to suggest that flame 

"lift-off" plays a significant role in DI diesel 

combustion and emissions formation processes, 

making lift-off length of significant practical 

importance to diesel engine designers. The lift-off 

length is the distance from the injector tip to the 

initial flame location on a DI diesel spray. As the 

injected fuel progresses through this region of the 

spray, air entrained into the spray mixes with the 

fuel. The fuel premixed with air upstream of the liftoff location, reacts in a fuel rich combustion zone 

just downstream of the lift-off length. The product 

gases of this rich reaction zone are conducive to 

forming soot. Measurements show that small soot 

particles begin forming in these product gases, and 

then grow as the gases are transported downstream in 

the spray.

The goal of this research is to investigate the soot 

formation process downstream of the lift-off length 

in DI diesel sprays and determine how various 

parameters affect this process. The first phase of this 

research is to determine the effects of injector and 

engine conditions on the lift-off length of a directinjection (DI) diesel spray. This investigation was 

started this year. Presently, there is very little 

understanding of the role that flame lift-off plays in 

DI diesel combustion and emissions formation 

processes. The lift-off length data are essential for 

understanding and interpreting the soot concentration 

measurements to be made downstream of the lift-off 

length in the next phase of the research. Improving 

our understanding of soot formation in a diesel spray, 

and the role that flame lift-off plays in the soot 

formation process, will aid the development of lower 

emission diesel engines.

In addition, during the past year the upgrade of 

the diesel combustion simulation facility used for 

these experiments was completed. 

Results

The research was performed in the Diesel 

Combustion Simulation Facility (DCSF) using an 

electronically controlled, common-rail diesel fuel 

Figure 1. Photograph of the combustion vessel in 

operation.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

98

injector. Figure 1 shows the picture of the opticallyaccessible combustion vessel in the DCSF. 

Parameters varied in the investigation included: 

injection pressure, orifice diameter, and ambient gas 

temperature and density. The fuel used was a 

Phillips research grade #2 diesel fuel.

An OH chemiluminescence imaging technique 

was developed for measuring the flame lift-off on DI 

diesel sprays. OH chemiluminescence is a known 

marker of high temperature combustion chemistry. 

Images of OH chemiluminescence at a wavelength of 

310 nm were acquired and analyzed to determine the 

upstream-most location of OH chemiluminescence, 

i.e., the lift-off length.

Figure 2 shows the lift-off lengths determined 

from images of OH chemiluminescence as a function 

of the ambient gas temperature for three different 

ambient gas densities. The general trends noted are a 

decrease in lift-off length with either increasing 

ambient gas temperature or density. The trend with 

respect to temperature is caused by an increase in 

flame speed with temperature that allows the flame 

on the spray to stabilize closer to the injector. The 

trend with respect to ambient gas density is caused 

by the effect of gas density on the overall spray 

development.

Figure 3 shows the effects of injection velocity 

(i.e., correlated with injection pressure) and orifice 

diameter on lift-off length. The effect of injection 

velocity on lift-off length is linear, with the lift-off 

length increasing as injection velocity increases. 

This same trend has been noted for atmospheric 

pressure gas jets and is caused by the flame being 

pushed further from the orifice by the higher 

injection velocities. Figure 3 also shows that as 

orifice diameter increases the lift-off length 

increases. This latter trend differs from the 

independence of lift-off length on orifice diameter 

noted for gas jets.

By combining the lift-off length results with our 

understanding of spray air entrainment, fuel 

vaporization, and overall spray development 

processes [Siebers, 1998 and 1999; Naber and 

Siebers, 1996], a picture of how parameters such as 

ambient gas density and temperature, injection 

pressure, and orifice diameter affect the DI diesel 

spray combustion process is beginning to emerge. 

The combined data, discussed by Siebers and 

Higgins [2000], suggests that the DI diesel 

combustion process has changed from one involving 

a core region, rich in liquid-phase fuel that is 

Figure 2. Lift-off length versus ambient gas temperature 

for three ambient gas densities. The orifice 

diameter and injection pressure drop across the 

orifice were 180 μm and 138 MPa, 

respectively. The gray region in the figure 

represents the range of lift-off lengths expected 

for typical engine conditions.

Figure 3. Lift-off length versus injection velocity for 

three orifice diameters. The injection velocity 

was determined from the measured injection 

pressure drop across the orifice, the orifice 

velocity coefficient, and Bernoulli’s equation. 

The ambient gas density and temperature were 

14.8 kg/m3 and 1000 K
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

99

surrounded by combustion, to one in which fuel 

vaporization is largely completed prior to any 

combustion (i.e., the current picture for heavy-duty 

diesels). The changes are due to greater air 

entrainment upstream of the lift-off length caused by 

changes in engine design made to meet more 

stringent emissions regulations over time. These 

changes include: increased injection pressure, 

reduced orifice diameter, and reduced in-cylinder gas 

temperature. 

Conclusions

Lift-off lengths determined from images of 

natural light emission at 310 nm show that as 

injection pressure (i.e., correlated with injection 

velocity) or orifice diameter increase, the lift-off 

length increases, and that as ambient gas density or 

temperature increase the lift-off length decreases. 

The results suggest that air entrainment upstream of 

the lift-off length will vary with conditions thus 

altering all remaining combustion and emissions 

formation processes downstream of the flame lift-off 

location.

An important overall observation was made by 

considering the lift-off length data in conjunction 

with liquid-phase fuel penetration and spray 

development data. The picture developed from the 

combined data suggests that DI diesel combustion 

and emission processes have been evolving over time 

in response to changes made to help meet emissions 

regulations. The trends observed will ultimately help 

explain observed effects of engine and injector 

parameters on soot formation. These trends will also 

provide robust tests for models being developed for 

DI diesel combustion and emissions processes. 

List of References

1. D. Siebers and B. Higgens, "Effects of Injector 

Conditions on the Flame Lift-Off Length of DI 

Diesel Sprays," accepted for Thiesel 2000, 

Conference on Thermofluidynamic Processes in 

Diesel Engines, Valencia, Spain, September, 

2000.

2. D. Siebers, "Scaling Liquid-Phase Fuel 

Penetration in Diesel Sprays Based on MixingLimited Vaporization," Paper No. 1999-01-0528, 

SAE International Congress, Detroit, MI, 

February, 1999.

3. D. Siebers, "Liquid-Phase Fuel Penetration in 

Diesel Sprays," Transactions of the SAE, Vol. 

107, Sec. 3, pp. 1205-1227, 1998.

4. J. Naber and D. Siebers, "Effects of Gas Density 

and Vaporization on Penetration and Dispersion 

of Diesel Sprays," Transactions of the SAE, Vol. 

105, Sec. 3, pp. 82-111, 1996.

List of Publications

1. D. L. Siebers and B. Higgens, "Effects of 

Injector Conditions on the Flame Lift-Off Length 

of DI Diesel Sprays," accepted for Thiesel 2000, 

Conference on Thermofluidynamic Processes in 

Diesel Engines, Valencia, Spain, September, 

2000.

List of Presentations

1. D. Siebers, "Diesel Spray Lifted Flame 

Phenomena," Diesel Combustion/Alternative 

Fuels CRADA Meeting, USCAR, Detroit, MI, 

June, 2000.

2. D. Siebers, "Diesel Combustion Cross-Cut 

Research," CIDI Combustion, Emission Control 

& Fuels R&D Laboratory Merit Review & Peer 

Evaluation, Argonne National Laboratory, 

Argonne, IL, May, 2000.

3. D. Siebers, "Diesel Spray Flame Lift-Off 

Research," OAAT Mid-Year Review, Sandia 

National Laboratories, Livermore, CA, 2000.

4. D. Siebers, "Progress on the Investigation of 

Flame Lift-Off in Diesel Sprays," Diesel 

Combustion/Alternative Fuels CRADA Meeting, 

Sandia National Laboratories, January, 2000.

5. D. Siebers, "Work in Progress - Diesel 

Combustion Simulation Facility," Diesel 

Combustion/Alternative Fuels CRADA Meeting, 

USCAR, Detroit, MI, October, 1999.

List of Acronyms

DCSF Diesel Combustion Simulation 

Facility

DI Direct injection

EGR Exhaust Gas Recirculation
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

100

D. Microwave-Regenerated Exhaust Particulate Filter Technology

Dick Nixdorf

Industrial Ceramic Solutions, LLC

1010 Commerce Park Drive, Suite I

Oak Ridge, TN 37830

(865) 482-7552, fax: (865) 482-7505, e-mail: nixdorfr@indceramicsolns.com

DOE Program Manager: Ken Howden

(202) 586-3631, fax: (202) 586-9811, e-mail: ken.howden@ee.doe.gov

DOE Program Manager: Kathi Epping

(202) 586-7425, fax: (202) 586-9811, e-mail: Kathi.Epping@hq.doe.gov

DOE Program Manager: Pat Davis

(202) 586-8061, fax: ( 202) 586-9811, e-mail: Patrick.Davis@ee.doe.gov

Subcontractors: Microwave Materials Technologies, Inc., Knoxville, TN

This Project addresses the following OTT R&D Plan Barriers and Tasks:

Barriers

B. PM Emissions

Tasks

5c. Microwave Regenerating Diesel Particulate Filter

Objectives

• Follow up the FY 1999 bench scale testing to actual engine test cell work on three types of diesel 

engines. 

• Demonstrate a 75% efficiency in the removal of exhaust particulate matter. 

• Demonstrate microwave regeneration efficiency to clean the filter to within 90% of the new filter 

condition, while the engine is operating at idle speed.

• Provide data on microwave regeneration power requirements and the frequency of regeneration cycles 

needed during typical diesel engine operating conditions in a light-duty vehicle.

Approach

• Design and fabricate a silicon carbide fiber filter cartridge and microwave regeneration system sized 

for a PNGV-type diesel engine.

• Test this microwave filter system on a Ford 1.2 liter DIATA diesel engine, an International 7.3 liter 

diesel engine, and a Volkswagen 1.9 liter diesel engine. 

• Analyze the data from the three diesel engine tests to determine particulate removal efficiency, 

regeneration efficiency, power required for microwave cleaning of the filter cartridge and approximate 

the cycle time between regenerations.
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

101

Accomplishments

• Over the three engine tests, the microwave filter system demonstrated 80% - 95% diesel particulate 

removal efficiency.

• Microwave regeneration of the filter cartridge, at engine idle operating conditions, demonstrated the 

ability to return the filter to within 95% - 100% of the "new" filter exhaust flow capacity. 

• Calculations based on the data showed that a 1.9 liter Volkswagen engine, operating at cruising speed, 

would require regeneration approximately every six hours. The regeneration will consume 1.75 kW of 

power over a period of two minutes.

• The fuel economy penalty assuming regeneration every six hours using 1.75 kW microwave power 

(2.7 kW engine electrical power) is estimated to be 0.3 percent. No estimate of the impact of increased 

engine backpressure on fuel economy was made, but it is believed to be minimal due to the low 

backpressure build-up before regeneration is triggered.

• This microwave regenerated filter system demonstrated potential compliance with the EPA 2007 Tier 

2 standards for diesel particulate emissions.

Future Directions

• Durability of the microwave regenerated filter system on an operating vehicle needs to be 

demonstrated. 

• The next step in the development will be the installation and durability testing of the filter system on a 

vehicle for road testing. 

• Future work will include product development of the microwave filter system for a selected car and 

engine type to demonstrate commercial potential.

Introduction

Current diesel engine particulate filter 

technologies depend on a catalyst to assist in the 

regeneration of the filter. Catalyst technology 

requires an exhaust temperature of approximately 

350o

C to be effective. Small diesel engines only 

achieve this exhaust temperature under hard 

acceleration, with extended high vehicle speeds, or 

by specific engine and fuel system manipulation 

techniques. The Microwave Regenerated Particulate 

Filter can achieve acceptable particulate removal 

efficiencies and regenerate at the low exhaust 

temperatures typical of light-duty vehicle urban 

driving cycle conditions. It may also be a solution to 

the cold-start HC and CO emissions from diesel and 

gasoline engines. Microwave heating of catalyst 

substrates and other diesel soot traps has been tried in 

previous investigations by others. This technology is 

unique due to the discovery of a special silicon 

carbide fiber that efficiently converts microwave 

energy to heat energy. A small mass of these fibers 

can achieve temperatures of 1,200o

C in 9 seconds in 

a standard household microwave oven. ICS has 

developed a process to incorporate this discovery 

into a filter cartridge and microwave regeneration 

system for use in diesel engine exhaust streams, as 

shown in Figure 1.

Figure 1. Microwave-Regenerated Ceramic Filter System
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

102

Approach

After FY 1999 bench testing, the microwave 

filter system has advanced to tests on commercial 

diesel engines. The first trial on a diesel engine for 

the microwave filter system occurred on the 1.2 liter 

DIATA diesel at the Ford Motor Company’s 

Scientific Research Laboratory. Figure 2 shows the 

entry and exit sides of the silicon carbide filter after a 

filtration cycle on the DIATA engine, where 86% of 

the diesel particulate was removed. Data were 

obtained to demonstrate particulate removal 

efficiency and regeneration efficiency. Since it takes 

several hours to load the silicon carbide fiber filter to 

the regeneration point on these small engines, the 

filter system was also tested on a production 7.3 liter 

diesel engine at the University of Tennessee. This 

larger engine allowed multiple loadings and 

regeneration cycles of the filter system in a relatively 

short period of time. That test apparatus, which is 

shown in Figure 3, provided data on the filter’s soot 

loading capacity, multiple consecutive regeneration 

cycle efficiencies, and the microwave regeneration 

power requirements. A final test to obtain analytical 

exhaust emissions data was conducted on a 1997 

Volkswagen 1.9 liter engine at the Oak Ridge 

National Laboratory diesel engine test facility. These 

data provided answers to the program evaluation 

committee’s questions on particle size distribution of 

the soot passing through the filter and on the 

emissions released during microwave regeneration of 

the filter. A combination of the results of the three 

diesel engine tests led to the calculation of the time 

span between regenerations and the fuel penalty for 

using the microwave regenerated particulate filter 

technology.

Results

Figure 4 shows the loading and microwave 

regeneration cycles of the filter system through six 

successive cycles during the International 7.3 liter 

diesel engine test. It should be noted that the last two 

regenerations returned the filter to 100% of its "new" 

filter condition (measured relative to the pressure 

drop at 60 cfm flowrate through a new filter). Figure 

5, based on the Volkswagen 1.9 liter diesel steadystate testing at ORNL, shows that the microwaveFigure 2. Entry and Exit Sides of the Filter Cartridge 

After a 1.2 Liter Diesel Engine Filtration Cycle

Figure 3. Test Apparatus on the Exhaust of a 7.3 Liter 

Light-Duty Diesel Truck

Figure 4. Pressure Differential across the Filter from 

Successive Loadings and Regenerations (7.3 

Liter Diesel Engine) 
Combustion and Emission Control for Advanced CIDI Engines FY 2000 Progress Report

103

regenerated filter is capable of compliance with the 

EPA Tier 2 particulate emission standards for diesel 

engines.

Conclusions

The FY 2000 objectives required a 75% 

reduction in diesel particulate; test results 

demonstrated an 85%-95% efficiency. The 

objectives required a 90% regeneration efficiency; 

test results demonstrated a 95%-100% regeneration 

efficiency. Most existing exhaust particulate 

reduction technologies come with a 5% fuel penalty; 

the microwave filter fuel penalty, as demonstrated in 

these tests, is 0.3%. Existing catalyst technologies 

require adjustments to engine operating conditions 

and/or the addition of fuel additives to regenerate at 

exhaust temperatures typical of light-duty diesel 

vehicle operation. The microwave system is 

independent of those adjustments and/or additives. 

These three tests on different types of commercial 

diesel engines demonstrate the ability of the 

Microwave Regenerated Diesel Particulate Filter 

System to provide a possible solution to particulate 

emission control issues for diesel vehicles. The next 

phase of durability testing, with on-road vehicle 

demonstrations, can lead to commercial development 

of the microwave system by the automotive 

companies.

List of Publications

1. Nixdorf, R. and J. Parks, "Emerging 

Technologies in Emission Abatement for Diesel 

Engines", page 10, CADDET Energy Efficiency 

Newsletter Number 2, June 2000.

List of Presentations

1. Nixdorf, R., "Microwave Regenerated 

Particulate Filter-Statement of Work", PNGV 

4SDI Committee; USCAR; Detroit, MI; March 

5, 2000.

2. Nixdorf, R., "Microwave Regenerated 

Particulate Filter-Project Status", PNGV 4SDI 

Committee; Detroit Diesel Corporation; Detroit, 

MI; March 5, 2000.

3. Nixdorf, R., "Microwave Regenerated 

Particulate Filter", DOE FY 2000 Merit Review 

and Peer Evaluation National Laboratory, 

Argonne National Laboratory, March 22, 2000.

List of Acronyms

CO Carbon monoxide

DIATA Direct Injection, Aluminum 

Through-bolt Assembly

HC Hydrocarbons

ICS Industrial Ceramic Solutions, LLC

PNGV Partnership for a New Generation of 

Vehicles

Figure 5. 1.9 Liter Volkswagen Filter Particulate 

Reduction Results (FTP simulation using 

steady-state tests)