Automotive Exhaust Emissions at Low Ambient Temperature

Experiments with gasoline and diesel engines has been carried out in a cold chamber at constant ambient temperature ranging from +20°C to −30°C.

The test results showed that in gasoline engines the use of the enrichment devices necessary during cold-start and warm-up period has a major impact on the total emissions of the engines. The carburetted test engines were also found to be quite sensitive to intake air temperature.

In case of a diesel engine cold start and ambient temperature has less effect on emissions because of the differences in mixture formation and combustion process. However, CO and HC emissions increased along with the smoke emission, when test temperature was lowered.