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Technical Paper

Alternative EHC Heating Patterns and Their Impact on Cold-Start Emissions Performance

1994-10-01
941996
EHC heating patterns which utilize zones covering less than the available inlet face cross-sectional area have been evaluated for cold-start FTP performance. Both NMHC and CO cold-start emission performance were found to be significantly reduced relative to an EHC-inactive basecase for heating patterns that covered as little as 44% of the cross-section. In low-mileage tests, NMHC and CO cold-start emission dependencies on heating patterns were found to be relatively constant for patterns with heating coverages of 44% or more of the inlet face cross-sectional area. In these low mileage tests, reductions in Bag 1 FTP NMHC and CO emissions averaged about 30% lower with the preferred zoned heating patterns relative to the EHC-inactive basecase. FTP tests run on a similar engine-aged EHC showed less asymptotic dependence on EHC zoned heating strategies.
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