Experimental analysis of inert gases in EGR on engine power and combustion characteristics in a stoichiometric dual fuel heavy-duty natural gas engine ignited with diesel

Abstract

Using three-way catalytic converter can greatly reduce emissions in stoichiometric condition as soot is very low in diesel pilot natural gas dual fuel engine. Previous studies have shown that EGR can improve engine performance at partial load in gasoline engine. To better understand the effect of EGR on engine performance of stoichiometric dual fuel engine, a detailed study on inert gases (Ar, N2, CO2) in EGR were conducted on a 6-cylinder turbocharged intercooler diesel/natural gas dual fuel heavy-duty engine at stoichiometric condition. In this experiment, the total fuel quantity, gas injection strategy and diesel injection strategy were kept unchanged. The results show that different inert gas has different effect on engine power and combustion characteristics. The engine power increased for Ar and N2 dilution, while it decreased for CO2 dilution with increasing the dilution ratio. The engine power with Ar dilution is highest, followed by N2 and CO2 dilution at same dilution ratio. Adding CO2 into the intake charge made the combustion process of the engine deteriorated most, including start of combustion, CA 50, heat release peak, the cylinder pressure peak, followed by N2 dilution. While, these parameters show opposite changes except heat release rate for adding Ar. What’s more, when considering different performance targets of dual fuel engine, different dilution gases are corresponding.