Abstract
A multi-dimensional combustion model combined with a detailed kinetics has been developed by the link between KIVA-3 and CHEMKIN-II with some modifications. In this model, various elementary reactions can be taken into account in a common CFD code. On the other hand, Homogeneous Charge Compression Ignition (HCCI) combustion has been attracting growing attention in recent years due to its potentials for simultaneously improving exhaust gas emissions and fuel consumption in both gasoline and diesel engines. However, it is difficult to control occurrences of violent pressure increases at the time of ignition in the HCCI combustion. In this paper, a numerical study was carried out to investigate the chemical reaction phenomena encountered in the HCCI combustion process of natural gas by the use of a developed CFD detailed kinetics model. In this model, 151 chemical species and 501 elementary reactions are taken into account. Fig. 1 shows that pressure, RHR and major chemical species mass histories in the cylinder as a whole obtained by a multi-dimensional model. As shown in this figure, hydrocarbons having higher carbon numbers are consumed ahead of time. During low-temperature reactions, HCHO and CO are formed gradually. When the high-temperature reaction occurs to accompany rapid pressure increases, these chemical species disappear. On the other hand, OH and CO_2 are formed rapidly at this term under this condition. Moreover, other results indicate iso-contours of temperature and various chemical species in the cylinder and the effects of its heterogeneity on HCCI ignition.
