Effects of diesel injection parameters on the rapid combustion and emissions of an HD common-rail diesel engine fueled with diesel-methanol dual-fuel

Abstract

The diesel-methanol dual-fuel (DMDF) combustion mode is performed on a 6-cylinder, heavy duty (HD), common-rail diesel engine. In DMDF mode, the methanol is premixed with air in the intake pipe and afterwards ignited by the direct-injected diesel in cylinder. This study is aimed to investigate the effects of diesel injection parameters on the rapid combustion and emissions of the DMDF engine. The experimental results show that the diesel injection parameters affect rapid combustion fraction (α) greatly, which increases as the diesel injection pressure rises while decreases as the diesel injection timing advanced or diesel injection quantity increases. The roar-combustion level of the DMDF engine is mainly controlled by the heat release rate (HRR) of rapid combustion phase. Both increasing the diesel injection pressure and advancing the diesel injection timing are beneficial to intensify roar-combustion level, but it can be weakened by increasing diesel injection quantity. Compared with original diesel combustion mode (D mode), NOx and smoke emissions in DMDF mode are all reduced, while CO and HC emissions increased obviously. Smoke emission can be further reduced by coupling the high diesel injection pressure and the advanced diesel injection timing. However, NOx emission may be increased in this case.