Combustion and emissions characteristics of methanol/gasoline CISI engines under different injection modes

Abstract

Methanol was a promising alternative fuel for spark ignition engines due to its liquid nature, large octane number and high oxygen content. The combined injection technology had the advantages of greater control flexibility, less engine knock tendency, and less engine-out emissions. However, the preferable injection mode of methanol/gasoline dual fuel engine was rarely reported. In this study, the combustion and emission characteristics of methanol/gasoline dual fuel engine with different injection modes, methanol direct injection plus gasoline port injection (MDI + GPI) or gasoline direct injection plus methanol port injection (GDI + MPI), were studied experimentally. The results showed that MDI + GPI mode was preferred for methanol/gasoline dual fuel engines, as this mode yielded higher engine brake effective mean pressure, larger heat release rate, lower cyclic variation, and less particle number emissions. An unimodal nucleation pattern particle size distribution can be observed for the MDI + GPI mode, which was beneficial for the after-treatment of particles in gasoline particle filter.