Development of a multizone model for direct injection diesel combustion

Abstract

Diesel engines have attracted considerable attention in recent years because of the increasingly restrictive ‘engine-out’ emission standards being adopted by regulatory agencies. The cutting-edge technologies of emissions reduction in engines fall into three categories: preprocessing, improved combustion processing and post-processing. An engine cycle simulation was developed to investigate and, thus, find possible avenues of reducing emissions through modifying the combustion process. This simulation includes models for fresh air charging, fuel and air mixing, wall heat transfer, diesel droplet evaporation, ignition delay and mixture combustion with species equilibrium reactions. These models, together with a thermo-dynamic analysis of the cylinder gas, yield instantaneous cylinder conditions, overall indicated engine performance and a prediction of the engine-out NOx and soot emissions. The engine parameters and operating conditions used in the work presented here were chosen to be representative of a Caterpillar 3401 single-cylinder diesel engine. Experimental investigations were also conducted with the engine, and the combustion model has been verified by comparing the experiment results to the simulation results.