Idle Emissions from Heavy-Duty Diesel and Natural Gas Vehicles at High Altitude |
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| Authors: | Robert L McCormick Michael S Graboski Teresa L Alleman Janet Yanowitz |
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| Institution: | 1. Colorado Institute for Fuels and Engine Research, Colorado School of Mines , Golden , Colorado , USA rlmccorm@mines.edu;3. Colorado Institute for Fuels and Engine Research, Colorado School of Mines , Golden , Colorado , USA |
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| Abstract: | ABSTRACT Idle emissions of total hydrocarbon (THC), CO, NOx, and particulate matter (PM) were measured from 24 heavy-duty diesel-fueled (12 trucks and 12 buses) and 4 heavy-duty compressed natural gas (CNG)-fueled vehicles. The volatile organic fraction (VOF) of PM and aldehyde emissions were also measured for many of the diesel vehicles. Experiments were conducted at 1609 m above sea level using a full exhaust flow dilution tunnel method identical to that used for heavy-duty engine Federal Test Procedure (FTP) testing. Diesel trucks averaged 0.170 g/min THC, 1.183 g/min CO, 1.416 g/min NOx, and 0.030 g/min PM. Diesel buses averaged 0.137 g/min THC, 1.326 g/min CO, 2.015 g/min NOx, and 0.048 g/min PM. Results are compared to idle emission factors from the MOBILE5 and PART5 inventory models. The models significantly (45-75%) overestimate emissions of THC and CO in comparison with results measured from the fleet of vehicles examined in this study. Measured NOx emissions were significantly higher (30-100%) than model predictions. For the pre-1999 (pre-consent decree) truck engines examined in this study, idle NOx emissions increased with Health and Environment; June 30, 1999 (available from the authors). |
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