Numerical and experimental study of combustion and emission characteristics in gasoline direct-injection compression ignition engines using intake preheating

Abstract

This paper presents a numerical and experimental study of the combustion and emission characteristics of a gasoline direct-injection compression ignition engine using intake preheating. The gasoline direct-injection compression ignition engine was predicted to reduce emissions compared with the emissions from a conventional diesel engine. To compare the combustion and emission characteristics of the gasoline direct-injection compression ignition and diesel engines, numerical modelling was conducted using the KIVA-3V release 2 code, which is integrated with the Chemkin chemistry solver II. Numerical simulations were performed under a variety of conditions to determine the optimal conditions for gasoline direct-injection compression ignition engine operation. In order to achieve the gas pressure in the cylinder and the emission characteristics, experiments were performed using a single-cylinder engine. The simulation results agreed well with the experimental data. The gasoline autoignition was in the parcels with a lower equivalence ratio of 0.6-0.8 as opposed to the diesel autoignition parcels with a high equivalence ratio of greater than 1. The ignition delay of gasoline was longer than that of diesel; therefore, the gasoline direct-injection compression ignition engine could reduce the soot emissions. The nitrogen oxide emission levels for gasoline direct-injection compression ignition were increased because of the intake preheating.