Modeling of the Effect of Air/Fuel Ratio and Temperature Distribution on HCCI Engines

A computer model has been developed to investigate the effect of temperature and air/fuel ratio inhomogeneity on HCCI combustion. Engine tests were performed to aid the model validation. After obtaining appropriate agreement between experimental pressure profiles and the computer simulation, it was found that two very important factors impact the pressure profiles; (1) the onset timing of the overall reaction, which is mainly governed by the highest temperature in the cylinder, and (2) the time lag between initial ignition and combustion in other regions, resulting from temperature and species inhomogeneity.