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An upgraded multizone model is developed in order to study the effects of fuel injection characteristics on DI diesel engine soot and NOx emissions. Effects of fuel spray characteristics, the movement and evaporation of droplet, and spray wall impingement are considered. NOx emission is predicted by the extended Zeldovich mechanism and soot emission is simulated by the current soot formation and oxidation model. The multizone model can be used to calculate cylinder pressure, heat release rate, engine performance, NOx and soot emissions, etc. In this paper, the boot injection and split injection are simulated. The simulation shows that the fuel injection characteristics have significant effects on the process of engine combustion and emissions. The NOx and PM emissions from DI diesel engine can be reduced simultaneously by optimizing the shape of injection rate, especially by boot injection.

Premixed charge compression ignition (PCCI) combustion has been shown to be a promising combustion technique to improve the combustion process and simultaneously reduce both Nitrogen oxides (NOx) and particulate matter (PM) emissions. The combination of port dimethyl ether (DME) induction and in-cylinder diesel direct-injection compression ignition (DICI) combustion was studied in a YTR 2105 engine. The main purposes of this paper were to investigate the effects of DME introduction on the combustion and emission characteristics of a diesel engine. Results obtained revealed that PCCI combustion process was composed of the homogeneous charge compression ignition (HCCI) combustion and conventional diffusion combustion. As the DME quantity was increased, the start of combustion (SOC) was advanced. The peak values of in-cylinder pressure and mass averaged temperature increased as well as the maximum heat release rate of DME HCCI combustion.