### 1

Factor development :

Optional e missions m a ss adjustment factor for evaporative emissions testing using California test fuel containing 10%

ethanol

February 21, 2012

Authored by: California Air Resources Board Staff

I. California Evaporative Emission Test Procedure diurnal mass equation derived for an ethanol containing fuel :

E di 

### = E HCd 

### + ( OEHCE EeOH 

### ) ( E EeOH 

### ) M ain equation

The “10

- 6 ” factor of the test procedure equation is not in the “main equation ” above since M EtOH is expressed in g in lieu of μ g just for the

purpose of developing this factor.



### Where:

E

HCd 

### = 2

. 97 ( P ) ( V ) × 10 − 4

T 

### { � PPE Cfid 

### �

− r a 

### ( PPE C EeOH 

### ) }

To simplify the calculation, initial concentrations assumed to be zero.

r a = the FI D response factor to ethanol

OEHCE EeOH = available HC mass of an et h anol molecule ( assuming a h ydrocarbon H : C ratio of 2

. 3 : 1 )

total mass of an et h anol molecule

Hydrocarbon H:C (hydrogen to carbon) ratio obtained from 40 CFR 86.143

- 96

OEHCE EeOH = 28

. 66

46

. 07

OMHCE EtOH = 0.62

### 2

E

EeOH 

### = ( C EeOH 

### ) ( EW EeOH 

### ) ( P ) ( V )

( R ) ( T )

C CEeOH = 2 ( C EeOH ) ( Concentration in terms of carbon )

PPE C EeOH = 10 6 × ( C C EeOH ) (PPM concentration in terms of carbon )

C

EeOH = PPM C EtOH

2 × 10 6



### E

EeOH 

### = ( PPE C EeOH 

### ) ( EW EeOH 

### ) ( P ) ( V )

( R ) ( T ) ( 2 ) ( 10 6 

### )

EW EeOH 

### = 46

. 07 grams

mole



### R =

. 0481 ( inHg ) ( ft 3 

### )

( mole ) ( ° R )

E

EeOH 

### = ( P ) ( V )

( T ) (

. 000479 ) ( PPE C EeOH 

### )

Combine sub

- components into main equation:

E di = ( P ) ( V )

T { (

. 000297 ) ( PPE Cfid )

− ( r a ) (

. 000297 ) ( PPE C EeOH ) + (

. 62 ) (

. 000479 ) ( PPE C EeOH ) }

E di = ( P ) ( V )

T � (

. 000297 ) ( PPE Cfid )

− ( r a ) (

. 000297 ) ( PPE C EeOH ) + (

. 000297 ) ( PPE C EeOH ) �

<V> E di = ( P ) ( V )

T (

. 000297 ) � ( PPE Cfid )

− ( r a ) ( PPE C EeOH ) + ( PPE C EeOH ) �

E di = ( P ) ( V )

T (

. 000297 ) [ ( PPE Cfid )

− ( r a − 1 ) ( PPE C EeOH ) ] HC + Ethanol direct accounting

### 3

II. California Evaporative Emission Test Procedure diurnal mass equation derived for FID response only:

E di FID only = ( P ) ( V )

T (

. 000297 ) ( PPE Cfid ) Ethanol FID response only



### III. Obtain mass adjustment factor from p ercent difference: ( M di



### ) versus ( M di FID only 

### ) :

Express PPM C EtOH in terms of PPM Cfid to eliminate a variable in 

### M di

.

To do this, use ethanol to hydrocarbon ratio:

From <V>:

E di =

( P ) ( V )

T (

. 000297 ) � ( PPE Cfid )

− ( r a ) ( PPE C EeOH ) � ( mass non

- ethanol HC component )

+ ( P ) ( V )

T (

. 000297 ) ( PPE C EeOH ) ( mass ethanol component, HC equivalent)

r

EeOH = mass et h anol component

, HC equivalent

mass non

− et h anol HC component

<W> r EeOH = ( P ) ( V )

T { (

. 000297 ) ( PPM C EtOH ) }

( P ) ( V )

T (

. 000297 ) � ( PPM Cfid )

− ( r a ) ( PPM C EtOH ) � (emissions ethanol ratio)

( r

EeOH ) ( PPE Cfid )

− ( r EeOH ) ( r a ) ( PPE C EeOH )

= PPE C EeOH

( r

EeOH ) ( PPE Cfid )

= PPE C EeOH + ( r EeOH ) ( r a ) ( PPE C EeOH )

P PE C EeOH { 1 + ( r EeOH ) ( r a ) }

= ( r EeOH ) ( PPE Cfid )

### 4

<X> PPE C EeOH = ( r EtOH ) ( PPM Cfid )

{ 1 + ( r EtOH ) ( r a ) }

<X> subbed into “ HC + Ethanol direct accounting ”:

E di simplified

= ( P ) ( V )

T (

. 000297 ) � ( PPE Cfid )

− ( r a − 1 ) ( r EeOH ) ( PPE Cfid )

{ 1 + ( r EeOH ) ( r a ) } �

E di simplified

= ( P ) ( V )

T (

. 000297 ) ( PPE Cfid ) � 1

− ( r a − 1 ) ( r EeOH )

{ 1 + ( r EeOH ) ( r a ) } �

Percent difference: ( M di simplified ) versus ( M di FID only ) :

% diff = ( P ) ( V )

T (

. 000297 ) ( PPE Cfid ) � 1

− ( r a − 1 ) ( r EeOH )

{ 1 + ( r EeOH ) ( r a ) } �

− ( P ) ( V )

T � (

. 000297 ) ( PPE Cfid ) �

( P ) ( V )

T � (

. 000297 ) ( PPE Cfid ) � × 100%

% diff = � 1

− ( r a − 1 ) ( r EeOH )

{ 1 + ( r EeOH ) ( r a ) } �

− 1

1 × 100%

% diff =

− ( r a − 1 ) ( r EeOH )

{ 1 + ( r EeOH ) ( r a ) } × 100%

% diff = ( 1

− r a ) ( r EeOH )

1 + ( r EeOH ) ( r a ) × 100%

### 5

This represents how much greater the reported diurnal mass would be if determined by subtracting out the FID response to etha nol and then

adding on actual ethanol, versus just calculating reported mass from the FID response only.

**TABLE 1**  **:** % diff data determined from ethanol/hydrocarbon ratios ( r

EtOH ) from different vehicles

Vehicle: Fuel tank

matl: r EtOH : % diff For

r

a = .69 : (%)

Zero

- evap 2004 MY Focus Metal .09 3

Near

- zero 2004 MY Impala Plastic .11 3

Near

- zero 2006 MY Taurus Metal .21 6

Near

- zero 2004 MY Camry Plastic .26 7

Near

- zero 2004 MY Ram 1500 Plastic .16 4

r EtOH (emissions ethanol ratio) values in Table 1 were determined using E

- 77

- 2b & E

- 77

- 2 3

- day diurnal speciation data , tested with 7psi E10

fuel

. Appendix 1 contains a spreadsheet detailing this calculation and shows the exact data which was used.

r a ( FID response factor to ethanol ) values in Table 1 originate from ARB FID data , with an average value of .69. This data set is shown in

Appendix 2.

The percent difference equation obtained above can be applied as follows to create an emissions mass adjustment factor for ethanol

(EMAF) for vehicles tested with a fuel with similar characteristics to the E10 fuel used in the development of th is factor . EMAF can be

multiplied by the FID response only mass em issions to account for ethanol mass emissions without separately measuring for ethanol in the

emissions :

Emissions m ass ad justment factor for ethanol = EMAF

= 1 + % diff

100%

EMAF = 1.08, based upon worst case r EtOH (emissions ethanol ratio , HC equivalent ) = .26 and average r a ( FID response factor to ethanol ) =

.69 , and a + .01 (added onto 1.07) compliance margin to account for small sample size

.

E di adjuseed = E di FID onl y × EEEE

E di adjuseed = E di FID only × 1

. 08

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Appendix 1: Evaporative Emissions Mass Adjus tment Factor (EMAF) Calculation

Evaporative emissions mass:

Vehicle: MY: Evap

Standard: Data

source: Vehicle

number: Mass

EtOH:

(mg) Mass

EtOH, HC

Equiv:

(mg) Total

evap

mass HC:

(mg) Mass non

ethanol

HC (mg): EtOH

fraction: rEtOH: EMAF

w/ ra

= .77: EMAF

w/ ra =

.56: EMAF

w/ ra =

.69:

Focus 2004 zero

evap E

- 77

- 2b 222b 37.91 23.50 287.6 264.10 0.13 0.09 1.02 1.04 1.03

Ram

1500 2004 near zero E

- 77

- 2b 213b 395.89 245.45 1769.4 1523.95 0.22 0.16 1.03 1.07 1.04

Impala 2004 near zero E

- 77

- 2b 210b 189.14 117.27 1192.5 1075.23 0.16 0.11 1.02 1.05 1.03

Camry 2004 near zero E

- 77

- 2 211 202.11 125.31 611.9 486.59 0.33 0.26 1.05 1.10 1.07

Taurus 2006 near zero E

- 77

- 2 212 101.32 62.82 360.79 297.97 0.28 0.21 1.04 1.08 1.06

ra: ra is the FID ethanol response

factor

0.77 max

0.56 min

0.69 avg

EtOH fraction is the mass proportion of ethanol in the total evaporative emissions

rEtOH is the mass of the ethanol component HC equivalent divided by the mass of the non

- ethanol HC component in the evaporative

emissions

Mass EtOH and total evap mass data came from the Coordinating Research Council reports refer r ed to in the "Data source" column above

### 7

1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 E

M

A

F

EtOH ratio 

# EMAF: Evaporative Emissions Mass Adjustment Factor for

Ethanol

ra = .77

ra = .56

ra = .69

Focus Impala Taurus Near

Zero Camry

Near Zero 

## EEEE = { 1 + ( 1

− r a 

## ) × ( r eee 

## )

1 + ( r eee 

## ) r a 

## }

Ram

1500

Near

Zero

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Appendix 2: Ethanol Response Factor (ra) Data From ARB FID Machines

FID EQUIP_ID ETHANOL_r a CALIB_DATE

1 0.6572 1/1/1997

1 0.6572 10/1/1997

1 0.6572 10/1/1998

1 0.6572 6/1/2001

1 0.7556 2/27/2002

1 0.7556 5/27/2002

2 0.734 1/1/2000

2 0.734 4/16/2002

2 0.7398 8/22/2003

3 0.598 1/1/1997

3 0.598 10/1/1997

3 0.598 8/2/2001

3 0.607 5/22/2002

3 0.7598 8/22/2003

4 0.7465 1/1/1997

4 0.7465 10/1/1997

4 0.7465 8/1/2001

4 0.763 7/16/2003

5 0.5591 1/1/1997

5 0.5591 7/1/1997

5 0.5591 10/1/1997

6 0.7591 8/28/2003

7 0.757 5/28/2002

VVT1 0.771668 7/14/2011 Average EtOH ra 0.69

VVT2 0.771881 7/20/2011 Max EtOH ra 0.77

VVT3 0.764846 7/25/2011 Min EtOH ra 0.56