Parametric investigation of low pressure dual-fuel direct injection on the combustion performance and emissions characteristics in a RCCI engine fueled with diesel and CH4

Abstract

Dual-fuel direct injection is one of the most promising ways to control mixing process in a dual-fuel engine. A low pressure dual-fuel direct injection (LPDDI) concept inspired by air-assisted direct injection (AADI) technology is presented in this paper and an experiment has been conducted to evaluate the potential of the LPDDI applied in a diesel/CH4 dual-fuel engine. The effects of diesel injection timings and CH4 injection timings on the combustion performance and emissions characteristics were investigated under a constant engine speed of 2000 rpm in a single cylinder research engine. Under the varying operation condition of diesel and CH4 injection timings, the cylinder pressure, Heat Release Rate (HRR), Peak Pressure Rise Rate (PPRR), CA10, CA50, combustion duration, coefficient of variation of indicated mean effective pressure (CoVimep), as well as regular emissions (THC, CO and NOx) are analyzed. The results indicated that the diesel and CH4 injection timings have significantly influence on the combustion process. An optimized combustion performance obtained at the earliest diesel injection timing of −250 °CA ATDC and the latest CH4 injection timing of −112 °CA ATDC in this work. Furthermore, the results also proved that the LPDDI can be successfully applied in diesel/CH4 dual-fuel engine and a RCCI combustion mode can be achieved.