Experimental Investigation On Combustion And Ionization During Cold Starting And Idling Of A Diesel Engine

Diesel engine performance during cold starting is very crucial for smooth engine start at undesirable emission level. The development of cold start strategies that improve combustion stability relies mainly on the understanding of the combustion process during the cold starting. Even for modern diesel engines, the conditions during the cold start is far from normal operation characterized by large amount of unburned hydrocarbon emissions and long start to idling time. Thus, the use of an in-cylinder combustion sensor to measure the combustion quality during engine starting can significantly improve engine cold start control strategies. The ion current sensor has the potential to be used as onboard sensor to measure the combustion process during engine operation and can be used as feedback to the engine control unit. The aim of this research is to study and determine the combustion instability and its impact on various combustion and ionization characteristics by performing cycle analysis for a comparison between engine performance using ultra low sulfur diesel (ULSD) and aviation jet propulsion (JP8) fuels during cold start at 25 degrees Celsius. It also shows a comparison between two ion current sensors during low load idling using the same fuels. For this purpose, the glow plug and fuel injector of VW 2.0L turbocharged diesel engine were modified and electrically insulated to be used as ion current sensors. The experimental test was conducted to study the combustion process and emission product produced during low load idling.