Abstract
It is known that HCCI operating range extends to higher loads by use of mixed fuel with different ignitability, because main heat release is delayed into the expansion stroke where reactant density is lower. In this study, effect of ignition mechanism of the main fuel on heat release phasing in dual-fuel HCCI combustion was investigated based on elementary reaction-kinetic mechanisms. Two kinds of dual-fuel, methane/DME and toluene/DME, were used for analysis. As the results, it was found that the induction period from low temperature reaction to the early stage of high temperature reaction is strongly influenced by the OH reactivity of the main fuel, as well as heat release during the induction period. The analysis suggested that toluene/DME mixed fuel has an advantage in the knock limit since heat release is largely retarded compared with methane/DME mixed fuel.
