Improved Quasi-dimensional Spray Combustion Model in DI Engine with Detailed Chemistry

In this paper, a quasi-dimensional multi-zone spray combustion model is developed to simulate the combustion and emission of direct injection engine fueled with dimethyl ether (DME). The analysis of the spray mixing process is based on a quasi-dimensional gas jet model which consists of integral continuity and momentum equations. The heterogeneous field of temperature and temporal distribution histories of fuel in the combustion chamber is considered by dividing the chamber into n-zones. The jet mixing models are used to determine the amount of fuel and entrained air in each zone available for combustion. The mass, energy and state equations are applied in each zone and the combustion process is controlled by chemical reactions which are calculated by adopting CHEMKIN code. The CHEMKIN libraries have been used to formulate a stiff chemical kinetic solver suitable for integration within the engine cycle simulation. The DME combustion is calculated by a chemical kinetic scheme with detailed mechanism (79 species and 399 reactions). The partial differential equations are solved using DVODE code. The results from the simulation studies have shown a good agreement with the measurements from the experimental engine. This study presents a methodology for the development of a reliable but simple multi-zone model. The results reported in this paper demonstrate the importance of coupling detailed chemistry descriptions with physical models to the simulation studies of combustion and exhaust emissions from DI engine operated with DME.