抄録
The ignition and combustion mechanisms of mixed fuels with different ignitability, toluene/DME, were investigated using elementary reaction models on the basis of both Emdee's toluene oxidation scheme and Curran's DME2000 scheme. Toluene is thermally stable with a high oxidation onset temperature, whereas DME has good ignitability with active low temperature oxidation reactions. When DME coexists, the toluene oxidation temperature decreased to a low temperature at which single toluene would not react. In this temperature range, toluene oxidation is totally controlled by OH supplied from DME low temperature mechanism. The subsequent excursive hot fame reaction is restrained because toluene oxidation proceeds in stages depending on a temperature rise. Therefore, it is suggested that the HCCI operation range could be extended to higher loads without knocking if DME quantity is adjusted so that the hot flame reaction shift to the piston expanding period.
