Reducing Cold Start Emissions from Automotive Diesel Engine at Cold Ambient Temperatures

Cold start performance of diesel engines is determined by engine design, fuel type, fuel injection strategies, lubricant and ambient temperature conditions. Prevailing emissions legislation regarding low temperature emission tests applicable for gasoline vehicles is likely to be implemented to diesel vehicles. The present research work investigates the effects of intake air heating on a Euro 5 diesel engine’s performance and exhaust emission (gaseous and particulate emissions) characteristics during the cold start followed by idling at cold ambient conditions. Heating of intake air entering the engine at cold ambient temperature conditions improved fuel combustion as well as reduced the cranking period and improved the fuel economy. More than 50% reduction in HC and 17% reduction in NO_X emissions were achieved by intake air heating. Number count of accumulation mode particulates were higher during cold start compared to idle operation for all the temperature conditions. Intake air heating decreased the particulate number and size that led to reduction in total particulate mass by higher than 50% and 75% during cold start and idle respectively. The intake air heating strategy improved the cold start performance of the diesel engine at cold ambient temperature conditions and thereby would reduce the overall driving cycle emissions.