A numerical study on soot formation and oxidation for a direct injection diesel engine

A numerical cycle model is developed to investigate the soot production in a direct injection (DI) diesel engine. The Surovikin and Fusco models for soot formation and the Nagle model for soot oxidation are used with the KIVA-3V code. In the Surovikin model, carbon radicals are produced from pyrolysis of fuel and soot particles grow through collisions with fuel molecules. In the Fusco model, the carbon radicals and acetylene are formed from pyrolysis of fuel. There, acetylene works for the growth of soot particles. From investigation of the effects of the operating conditions on soot formation and oxidation, it is found that soot formation is mainly governed by fuel concentration and combustion temperature and soot oxidation is more dependent on combustion temperature. The air-fuel ratio affects soot formation more than injection timing. For a stoichiometric mixture ratio, soot formation is increased because of the high combustion temperature.