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Real-Time Evaporative Emissions Measurement: Mid-Morning Commute and Partial Diurnal Events
Technical Paper
2000-01-2959
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Real-time evaporative emissions test data were obtained for thirty-six 1977 to 1989 model year vehicles under conditions representative of a California mid-morning commute. The test procedure involved a cold soak followed by a driving event using the LA92 cycle, followed by a hot soak at 75°F and then a diurnal event where the ambient temperature was increased from 75 to 84°F over six hours. Ambient temperature then decreased from 84°F to 60°F over the next 13 hours and then was increased from 60°F to 75°F over the final five hours of the test.
Overall, the test results could generally be described by three types of responses:
- 1High hot soak emissions that continued for much longer than one hour and only a minimal increase in the rate of evaporative emissions during the heat builds of the diurnal test;
- 2High and extended hot soak emissions coupled with substantial emissions during one or both of the heat builds during the diurnal test; and
- 3Low hot soak emissions coupled with only a minimal increase in the rate of evaporative emissions during the two heat builds of the diurnal test.
In general, vehicles that failed an inspection and maintenance (I/M) type canister purge test tended to exhibit the first response, while vehicles that failed an I/M-type evaporative system pressure test tended to exhibit the second response. As expected, vehicles passing both types of I/M tests and gas cap pressure tests tended to exhibit the third response, and had low hot soak and diurnal emissions.
The real-time evaporative emissions data obtained from the nineteen 1980-1985 model year vehicles in the 36-vehicle fleet were compared with emission predictions from draft versions of the evaporative emissions algorithms of EPA's MOBILE6 and CARB's EMFAC2000 models. This comparison indicates that, for the 19-vehicle fleet, both models underestimated the magnitude and duration of hot soak emissions. In contrast, both models overestimated the magnitude of partial-day diurnal emissions for the same fleet. Further, a comparison of model results with data representative of a mid-morning commute indicates that MOBILE6 underpredicted emissions from the 19 vehicles while EMFAC2000 overpredicted emissions.
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Delaney, S., Heirigs, P., and Lyons, J., "Real-Time Evaporative Emissions Measurement: Mid-Morning Commute and Partial Diurnal Events," SAE Technical Paper 2000-01-2959, 2000, https://doi.org/10.4271/2000-01-2959.Also In
References
- Landman, Larry C. “Modeling Hourly Diurnal Emissions and Interrupted Diurnal Emissions Based on Real-Time Diurnal Data,” July 1999
- “Update of Hot Soak Emissions,” ARCADIS Geraghty & Miller, Inc. February 1999
- McClement, Dennis “Raw Fuel Leak Survey in I/M Lanes,” Automotive Testing Laboratories, Inc. June 1998
- “Evaluating Resting Loss and Diurnal Evaporative Emissions Using RTD Tests,” Personal Communication with Larry Landman of EPA March 30 2000
- “Hot Soak Emissions” “Diurnal and Resting Loss Emissions,” http://www.arb.ca.gov/msei/doctable.htm January 2000
- Brooks, David J. et. al. “Real World Hot Soak Evaporative Emissions - A Pilot Study,” SAE Tech. Paper Series, No. 951007 1995
- “Real World Hot Soak Evaporative Emissions,” Automotive Testing Laboratories, Inc. January 1996