NOTICE

This technical report does not necessarily represent final EPA decisions or positions. It is intended to present technical analysis of issues using data that are currently available. The purpose in the release of such reports is to facilitate the exchange of technical information and to inform the public of technical developments. 

### Assessment and Standards Division Office of Transportation and Air Quality U.S. Environmental Protection Agency

National Renewable Energy Laboratory U.S. Department of Energy

Coordinating Research Council 

# EPAct/V2/E

- 89: Assessing the Effect of Five Gasoline Properties on Exhaust Emissions from Light

- Duty Vehicles Certified to Tier 2 Standards

Final Report on Program Design and Data Collection

Appendix N EPAct NMOG Calculation Protocol

E PA-420-R-13-004 April 2013

### N-1 EPAct NMOG Calculation Protocol

19- Feb -2009

The series of calculations shown here (Equations (1) through (6)) must be performed separately for each test phase (bag). The NMOG mass results can then be weighed in the usual way to form a test cycle composite emission rate.

First we calculate correct ed NMHC concentration for dilute exhaust (subscript e) and dilution air (subscript d) as follows:

e AcetHO e OH Pre EtOH e MeOH e 4 CH e e AcetHO rOH Pr rEtOHrMeOH r4CHrFIDHC NMHC

⋅−⋅−⋅−⋅−⋅− = 

### (1)

d AcetHO d OH Prd EtOH d MeOH d 4 CH d d AcetHO rOH Pr rEtOHrMeOH r4CHrFIDHC NMHC

⋅−⋅−⋅−⋅−⋅− = 

### (2)

Note that these values are all as ppmC (so speciation results for EtOH, PrOH, and AcetHO reported in ppm of the particular chemical compound will need to be multiplied by 2 or 3 depending on the number of C atoms in the compound).

The following constant values shall be used for FID response factors:

r CH4 = 1.15 ppmC/ppmC (this program)

r MeOH = 0.63 ppmC/ppmC (this program)

r EtOH = 0.74 ppmC/ppmC (this program)

r PrOH = 0.85 ppmC/ppmC (CARB)

r FormHO = 0.00 ppmC/ppmC (various sources)

r AcetHO = 0.51 ppmC/ppmC (this program)



### Next, we must calculate the dilution factor to be used in g enerating the net NMHC concentration:



## ( ) ( ) 4

e e e e e e e e e 10CO AcetHO FormHO EtOH OH Pr MeOH4CH NMHC 2CO z5.0y25.0x76.3y5.0x x 100

DF

− ⋅+ + +++++ +      

−+⋅++ ⋅

= 

### (3)

The parameters x, y and z in Eq. (3) are coefficients taken from the chemical formula C x 

### H y 

### O z 

### of a test fuel. The procedure to calculate their values is provided in Appendix 2.

Once the DF is determined, we calculate the net NMHC concentration as follows:

     

−⋅−= DF 1 1NMHC NMHC NMHC d e conc 

### (4)

Then we compute NMHC mass 

### :

6

conc NMHC mix mass 10 NMHC Density V NMHC

−

⋅ ⋅ ⋅= 

### (5)

### N-2 Equations (4) and (5) must be repeated for each emission being considered. V mix 

### is the volume of dilute exhaust collected during a given phase of the test cycle, measured in standard cubic feet. Density is the calculated gas phase density of a particular species treated as a C 1 

### H y 

### O z 

### ideal gas.

The following values of gas phase density shall be used:

Density NMHC = 16.334 g/ft 3 Density MeOH = 37.718 g/ft 3 Density EtOH = 27.115 g/ft 3 Density PrOH = 23.581 g/ft 3 Density FormHO = 35.345 g/ft 3 Density AcetHO = 25.929 g/ft 3



### To generate the NMOG figure, we need methanol, ethanol, 2-propanol, formaldehyde and acetaldehyde mass emissions as computed using Eq. (4) and (5) based on measured concentration values form the speciation results (as in Eq. (1) and (2)).

Finally, then, NMOG mass emissions can be computed as follows:

mass mass mass mass mass mass mass AcetHO FormHO OH Pr EtOH MeOH NMHC NMOG + + + + + = 

### (6)

Once NMOG mass 

### calculations have been completed for all three phases (cold transient (ct), stabilized (s) and hot transient (ht)) of the LA92 test cycle they, calculate the total weighted NMOG emissions using the following formula:

               

+ +

⋅+ + +

⋅=

s D ht D mass.s NMOG mass.ht NMOG 0.57

s D ct D mass.s NMOG mass.ct NMOG 0.43 wm NMOG 

### (7)

For tes ts where there is no bag 2 or 3 speciation data, NMOG shall be computed assuming emission levels for oxygenated species in bags 2 and 3 are zero.

### N-3 Attachment 1

Definitions

NMHC e 

### – Concentration of NMHC in dilute exhaust sample, ppm C equivalent FIDHC e 

### - Uncorrected concentration of HC in dilute exhaust sample as measured by the FID, ppm C equivalent CH4 e 

### – Concentration of methane in dilute exhaust sample as measured, ppm C equivalent MeOH e 

### - Concentration of methanol in dilute exhaust sample as measured, ppm C equivalent EtOH e 

### - Concentration of ethanol in dilute exhaust sample as measured, ppm C equivalent PrOH e 

### - Concentration of 2-propanol in dilute exhaust sample as measured, ppm C equivalent FormHO e 

### - Concentration of formaldehyde in dilut e exhaust sample as measured, ppm C equivalent AcetHO e 

### - Concentration of acetaldehyde in dilute exhaust sample as measured, ppm C equivalent CO2 e 

### - Concentration of carbon dioxide in dilute exhaust sample as measured, percent CO e 

### - Concentration of carbon monoxide in dilute exhaust sample as measured, ppm

r CH4 

### - FID response to methane, ppmC/ppmC

r MeOH 

### - FID response to methanol, ppmC/ppmC

r EtOH 

### - FID response to ethanol, ppmC/ppmC

r PrOH 

### - FID response to 2-propanol, ppmC/ppmC

r FormHO 

### - FID response to formaldehyde, ppmC/ppmC

r AcetHO 

### - FID response to acetaldehyde, ppmC/ppmC NMHC d 

### - NMHC concentration in dilution air, ppm C equivalent FIDHC d 

### - Uncorrected HC concentration in dilution air sample as measured by the FID, ppm C equivalent CH4 d 

### - Concentration of methane in dilution air sample as measured, ppm C equivalent MeOH d 

### - Concentration of methanol in dilution air sample as measured, ppm C equivalent EtOH d 

### - Concentration of ethanol in dilution air sample as measured, ppm C equivalent PrOH d 

### - Concentration of 2-propanol in dilution air sample as measured, ppm C equivalent FormHO d 

### - Concentration of formaldehyde in dilution air sample as measured, ppm C equivalent AcetHO d 

### - Concentration of acetaldehyde in dilution air sample as measured, ppm C equivalent

DF



### - Dilution factor

x 

### - Carbon- to -carbon ratio in formula C x 

### H y 

### O z 

### determined as in Appendix 2 for the fuel used (by definition x=1)

y 

### - Hydrogen- to -carbon ratio in formula C x 

### H y 

### O z 

### determined as in Appendix 2 for the fuel used

z 

### - Oxyge n- to -carbon ratio in formula C x 

### H y 

### O z 

### determined as in Appendix 2 for the fuel used X – Carbon mass fraction of the fuel Y – Hydrogen mass fraction of the fuel Z – Oxygen mass fraction of the fuel NMHC conc 

### – Concentration of NMHC in dilute exhaust sample corrected for background, ppm C equivalent MeOH conc 

### - Concentration of methanol in dilute exhaust sample corrected for background, ppm C equivalent

### N-4 EtOH conc 

### - Concentration of ethanol in dilute exhaust sample corrected for background, ppm C equiva lent PrOH conc 

### - Concentration of 2-propanol in dilute exhaust sample corrected for background, ppm C equivalent FormHO conc 

### - Concentration of formaldehyde in dilute exhaust sample corrected for background, ppm C equivalent AcetHO conc 

### - Concentration of acetaldehyde in dilute exhaust sample corrected for background, ppm C equivalent V mix 

### - Volume of dilute exhaust collected during a given phase of the test cycle, scf Density NMHC 

### – Density of NMHC treated as a C 1 

### H y 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg, g/ft 3 

### Density MeOH 

### - Density of methanol treated as a C 1 

### H y 

### O z 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg, g/ft 3 

### Density EtOH 

### - Density of ethanol treated as a C 1 

### H y 

### O z 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg, g/ft 3 

### Density PrOH 

### - Density of 2-propanol treated as a C 1 

### H y 

### O z 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg, g/ft 3 

### Density FormHO 

### - Density of formaldehyde treated as a C 1 

### H y 

### O z 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg,ft 3



### Densi ty AcetHO 

### - Density of acetaldehyde treated as a C 1 

### H y 

### O z 

### ideal gas at standard conditions of 293.16 o 

### K and 760 mm Hg, g/ft 3



### M NMHC 

### - Molecular mass of NMHC treated as a C 1 

### H y 

### , g/mole, calculated according to the formula provided in Appendix 3 NMOG mass 

### - NMOG ma ss, g/test phase NMHC mass 

### - NMHC mass, g/test phase MeOH mass 

### - Methanol mass, g/test phase EtOH mass 

### - Ethanol mass, g/test phase PrOH mass 

### - 2-propanol mass, g/test phase FormHO mass 

### - Formaldehyde mass, g/test phase AcetHO mass 

### - Acetaldehyde mass, g/test phase NMOG wm 

### – Weighted NMOG emissions, g/mile NMOG mass.ct 

### - NMOG mass emitted during the cold transient phase of the test cycle, g/test phase NMOG mass.s 

### - NMOG mass emitted during the stabilized phase of the test cycle, g/test phase NMOG mass.ht 

### - NMOG mass emitted during the hot transient phase of the test cycle, g/test phase D ct 

### - Distance driven by the test vehicle on a chassis dynamometer during the cold transient phase of the LA92 test cycle, miles D s 

### - Distance driven by t he test vehicle on a chassis dynamometer during the stabilized phase of the LA92 test cycle, miles D ht 

### - Distance driven by the test vehicle on a chassis dynamometer during the hot transient phase of the LA92 test cycle, miles

### K-5 Attachment 2

Calc ulation of x, y and z Coefficients in Formula C x 

### H y 

### O z 

### Using Fuel C, H and O Content Data

The carbon- to -carbon ratio x in formula C x 

### H y 

### O z 

### by definition equals 1. The hydrogen- to -carbon and oxygen- to

- carbon ratios y and z, respectively, can be calculated usi ng the following equations:

12.011 X 1.008

Y

y = 

### (A2.1) and

12.011 X 15.999 Z

z = 

### (A2.2) where:

X – Carbon mass fraction of the fuel Y – Hydrogen mass fraction of the fuel Z – Oxygen mass fraction of the fuel



### The values of X, Y and Z will be provided by the EPA for all fuels tested in the EPAct Program.