Abstract
The main problems that need to be solved for future direct injection diesel engines are NOx and PM emissions. Emissions during cold start and engine warm-up are significant for overall emissions with respect to Euro 4 regulations (however not so significant as in spark-ignition engines), during the cold start and initial warm up conditions, fuel atomisation, mixture formation and combustion are poor, and in addition after-treatment devices (e.g. oxidising catalysts) do not work properly. This paper reviews the HC, CO and PM emissions from a direct injection (DI) diesel engine in the initial period of controlled engine operation following start-up. The tests were undertaken in 'cold start' mode (temperatures of cooling water and lube oil ambient following standard soak). The tests were undertaken on an European manufactured passenger car with high-speed, four cylinder, turbocharged, direct-injection diesel engine with swept volume of approximately 2 dm3 on a chassis dynamometer and on an engine test bench.