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Slide 1 of 48 M6 Workshop June 1999
EVAPORATIVE EMISSIONS IN MOBILE6
LARRY LANDMAN
MOBILE6 Workshop
June 29 - 30, 1999
Slide 2 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 3 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 4 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 5 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 6 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 7 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Hot Soak Emissions
Crankcase Emissions
Refueling Emissions
Resting Loss Emissions
Diurnal Emissions
Running Loss Emissions
Slide 8 of 48 M6 Workshop June 1999
Overview of This Presentation
Stratification
» Of Analyses
» Weighting Factors
Sources of Evaporative Emissions
» Diurnal Emissions
» Running Loss Emissions
Slide 9 of 48 M6 Workshop June 1999
Overview of This Presentation
Stratification
» Of Analyses
» Weighting Factors
Sources of Evaporative Emissions
» Diurnal Emissions
» Running Loss Emissions
Slide 10 of 48 M6 Workshop June 1999
Overview of This Presentation
Stratification
» Of Analyses
» Weighting Factors
Sources of Evaporative Emissions
» Diurnal Emissions
» Running Loss Emissions
Slide 11 of 48 M6 Workshop June 1999
Overview of This Presentation
Stratification
» Of Analyses
» Weighting Factors
Sources of Evaporative Emissions
» Diurnal Emissions
» Running Loss Emissions
Slide 12 of 48 M6 Workshop June 1999
Stratification
Of Analyses
Slide 13 of 48 M6 Workshop June 1999
Stratification for Each Source
For each type of source, the evaporative emissions were estimated separately for each of the following four strata: ALL “gross liquid leakers”
NOT “gross liquid leakers”
» Passing both purge & pressure
» Failing the pressure test
» Failing only the purge test
Slide 14 of 48 M6 Workshop June 1999
Stratification
Weighting Factors
Slide 15 of 48 M6 Workshop June 1999
Weighting Factors
For each of the four strata, the incidence of its occurrence (frequency) is estimated as a logistic growth function of vehicle age.
Slide 16 of 48 M6 Workshop June 1999
Weighting Factors
For each of the four strata, the incidence of its occurrence (frequency) is estimated as a logistic growth function of vehicle age.
Vehicle Age (years)
Fre
quency (%
)
Slide 17 of 48 M6 Workshop June 1999
“Gross Liquid Leakers”
The First of the Four Strata Many vehicles may have leaks of liquid
gasoline, but NOT all are “Gross Liquid Leakers”
Only the highest emitting of the leakers are “Gross Liquid Leakers”
Some vehicles may be “Gross Liquid Leakers” on only some of the tests
Slide 18 of 48 M6 Workshop June 1999
“Gross Liquid Leakers”
These are vehicles with substantial leaks of liquid gasoline (as opposed to vapor leaks) and having:
Resting Loss Emissions > 2.0 grams/hr, or
Diurnal Emissions > 25.0 grams/day, or
Hot Soak Test > 10.0 grams/test, or
Running Loss Test > 7.0 grams/mile
Slide 19 of 48 M6 Workshop June 1999
“Gross Liquid Leakers”
Frequency (From M6.EVP.009)
Vehicle Age (years)
Gro
ss L
iquid
Leake
r Rate
(%
)
0%
5%
10%
15%
0 10 20 30
Hot Soak Test RTD Test
Running Loss Test
Slide 20 of 48 M6 Workshop June 1999
“Gross Liquid Leakers”
Mean Emissions
Mean emissions from each source are: Resting Loss Emissions = 9.16 grams / hr
Diurnal Emissions = 104.36 grams / day
Running Loss Test* = 17.65 grams / mile
Hot Soak Test*
» Carbureted = 16.95 grams / test
» TBI = 45.00 grams / test
» PFI = 57.14 grams / test
Slide 21 of 48 M6 Workshop June 1999
Weighting FactorsVehicles NOT “Gross Liquid Leakers”
Data Sources
» I/M Lanes in Indiana and Arizona
Statistical Model
» Logistic Growth Curves
Compare Purge/Pressure Strata
Slide 22 of 48 M6 Workshop June 1999
Weighting FactorsCompare Purge & Pressure Strata
Vehicle Age (years)
Fre
quency
(%
)
0%
25%
50%
75%
100%
0 5 10 15 20 25
Pass Both Purge and Pressure
Fail Pressure
Fail ONLY Purge
Slide 23 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Diurnal Emissions
Slide 24 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 25 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal– 1995 and Older Vehicles -- No
Change from Previous Workshop– 1996 and Newer Vehicles -- New
Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 26 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal– 1995 and Older Vehicles -- No Change
from Previous Workshop– 1996 and Newer Vehicles -- New
Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 27 of 48 M6 Workshop June 1999
1996 and Newer Vehicles(“Enhanced EVAP” Vehicles)
More Stringent Standards » Phasing-In 1996-98 Model Years» Fully Applicable 1999 and Newer
Expected Effects of Standards » On Weighting Factors» On Emission Levels
Slide 28 of 48 M6 Workshop June 1999
Enhanced EVAP Vehicles
Basic Assumptions (from Report
M6.EVP.005 that is posted on website):
Effects on Distribution of Purge/ Pressure Strata
Effects on Average (Mean) Emission Level of Each Strata
Slide 29 of 48 M6 Workshop June 1999
Enhanced EVAP Vehicles Passing Both Purge & Pressure Tests
Vehicle Age (years)
Fre
quency
(%
)
0%
25%
50%
75%
100%
0 5 10 15 20 25
Enhanced
Pre-1996
Slide 30 of 48 M6 Workshop June 1999
Enhanced EVAP Vehicles
Basic Assumptions (from Report
M6.EVP.005 that is posted on website):
Effects on Distribution of Purge/ Pressure Strata
Effects on Average (Mean) Emission Level of Each Strata
Slide 31 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal– 1995 and Older Vehicles -- No Change
from Previous Workshop– 1996 and Newer Vehicles -- New
Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 32 of 48 M6 Workshop June 1999
Multi-Day Diurnals
Multiplicative factors (by strata) for second and third days.
(Unchanged After Third Day)
(Report No. M6.EVP.003)
Slide 33 of 48 M6 Workshop June 1999
Multiplicative FactorsMulti-Day RTD Tests
Fuel-Injected -- Passing Both » Day_2 = 1.365 * Day_1» Day_3 = 1.312 * Day_2 = 1.791 * Day_1
Fuel-Injected -- Failing Either » Day_2 = 1.133 * Day_1» Day_3 = 1.000 * Day_2 = 1.133 * Day_1
All Other Strata (i.e., Carbureted) » No Statistically Significant Changes from
Day-to-Day
Slide 34 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal– 1995 and Older Vehicles -- No Change
from Previous Workshop– 1996 and Newer Vehicles -- New
Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 35 of 48 M6 Workshop June 1999
Hourly Diurnals
Revised Approach Based On:
Purge / Pressure Strata
Fuel Delivery System (Carbureted versus FI)
Temperature Cycle
Fuel RVP
Report Number: M6.EVP.002 -- New Version
Slide 36 of 48 M6 Workshop June 1999
Diurnal Emissions
Full 24-Hour Diurnal– 1995 and Older Vehicles -- No Change
from Previous Workshop– 1996 and Newer Vehicles -- New
Multi-Day Diurnals Hourly Diurnals Interrupted Diurnals
Slide 37 of 48 M6 Workshop June 1999
Interrupted Diurnals
Situation in which the vehicle operation (driving) occurs after the daily temperature rise has already begun.
Calculations are based on ambient temperature at the time the diurnal emissions resume.
Slide 38 of 48 M6 Workshop June 1999
Sources of Evaporative Emissions
Running Loss Emissions
Slide 39 of 48 M6 Workshop June 1999
Running Loss Emissions
Evaporative Emissions Produced During Vehicle Operation
To Calculate, Subtract Resting Loss Emissions From Running
Loss Test Results See Report Number: M6.EVP.008
Slide 40 of 48 M6 Workshop June 1999
Running Loss Emissions
EPA’s Test Data Primarily Used for MOBILE5
Additional Testing Run for CRC»200 Test Vehicles»Limited Range of Ambient
Temperatures, Fuel RVP, and Driving Cycle
Slide 41 of 48 M6 Workshop June 1999
Running Loss Emissions
Comparing the predictions of resting loss from the MOBILE5 model (adjusted for new Purge and Pressure rates) to results from CRC’s 200-vehicle testing.
Slide 42 of 48 M6 Workshop June 1999
Running Loss Emissions
Mean Emissions of CRC Testing
Vehicle Age (years)
Runnin
g L
oss
Em
issi
ons
(g/m
i)
0.0
1.0
2.0
3.0
0 5 10 15 20 25
Slide 43 of 48 M6 Workshop June 1999
Running Loss Emissions
Comparison Between CRC Data and M5
Vehicle Age (years)
Runnin
g L
oss
Em
issi
ons
(g/m
i)
0.0
1.0
2.0
3.0
0 5 10 15 20 25
Slide 44 of 48 M6 Workshop June 1999
Running Loss Emissions Removing “Gross Liquid Leakers” from CRC Data
Vehicle Age (years)
Runnin
g L
oss
Em
issi
ons
(g/m
i)
0.0
1.0
2.0
3.0
0 5 10 15 20 25
Slide 45 of 48 M6 Workshop June 1999
Running Loss Emissions
Proposals for MOBILE6
For Vehicles Not “Gross Liquid Leakers,” Use MOBILE5 Predictions Within Each Purge/Pressure Stratum
Weight Those Three Strata With the New Stratum of “Gross Liquid Leakers”
Slide 46 of 48 M6 Workshop June 1999
References
M6.EVP.001 -- “Evaluating Resting Loss and Diurnal Evaporative Emissions Using Real Time Diurnal Tests”
M6.EVP.002 -- “Modeling Hourly Diurnal and Interrupted Diurnal Emissions Based on Real-time Data”
M6.EVP.003 -- “Evaluating Multiple Day Diurnal Evaporative Emissions Using RTD Tests”
Slide 47 of 48 M6 Workshop June 1999
References (Continued)
M6.EVP.004 -- “Update of Hot Soak Emissions Analysis”
M6.EVP.005 -- “Modeling Diurnal and Resting Loss Emissions from Vehicles Certified to Enhanced Evaporative Standards”
M6.EVP.006 -- “Estimating Weighting Factors for Evaporative Emissions in MOBILE6”
Slide 48 of 48 M6 Workshop June 1999
References (Continued)
M6.EVP.007 -- “Hot Soak Emissions as a function of Soak Time”
M6.EVP.008 -- “Estimating Running Loss Evaporative Emissions in MOBILE6”
M6.EVP.009 -- “Evaporative Emissions of Gross Liquid Leakers in MOBILE6”