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ANALYSIS OF REAL-TIME VEHICLE HYDROCARBON EMISSIONS DATA
Childress, J. AND J. Wilson Jr. ANALYSIS OF REAL-TIME VEHICLE HYDROCARBON EMISSIONS DATA. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-94/059a (NTIS PB94-501780), 1994.
The report gives results of analyses using real-time dynamometer test emissions data from 13 passenger cars to examine variations in emissions during different speeds or modes of travel. The resulting data provided a way to separately identify idle, cruise, acceleration, and deceleration emissions for examining how emissions differ by vehicle speed during cruise mode. To select a set of vehicles for the study, the hydrocarbon/time relationship was established for several vehicles operating on summer grade base fuel. Federal Test Procedure (FTP) results were then produced and examined to identify normal emitters (clean vehicles). After these vehicles were selected, their second-by-second emission characteristics were analyzed. The FTP runs for cold start, hot start, and hot stabilized emissions (Bags 1, 2, and 3 of the FTP) were performed for each of the four driving cycles - acceleration, deceleration, idling, and cruise - and the fraction of overall emissions contributed by each mode was computed for the warmed-up portion of the driving cycle. A protocol was then developed for review of the FTP real-time data. Study results showed significant emissions differences relating to the travel mode.