Experimental investigation on combustion and emission characteristics of diesel methanol dual fuel (DMDF) engine at various altitudes

In order to reveal the effects of diesel and diesel methanol dual fuel (DMDF) on engine performance at different altitudes, especially on combustion stability. In this study, a comparison of experimental research on characteristics of combustion, economy, and emissions for a turbocharged DMDF at various simulated altitudes (10m, 700m, 1670m, and 2400m) and three working conditions (1200rpm-72 Nm, 1800rpm-158 Nm, and 2200rpm-153 Nm) were conducted and analyzed combustion characteristics, economy and emissions. At 1800rpm and 2200rpm, with the increment of altitude, the peak value of the cylinder pressure, the pressure rise rate, and the brake thermal efficiency (BTE) for DMDF mode were higher than diesel mode, while combustion center (CA50) and combustion duration of diesel mode higher than DMDF mode. At 1200rpm and 1800 rpm, the maximum heat release rate (HRR) of DMDF mode was higher than diesel mode. When the altitude rose from 10m to 2400m, the coefficient of variation of peak pressure (COVPP) of DMDF mode increased while the coefficient of variation of indicated mean effective pressure (COVIMEP) of DMDF mode decreased, which means the combustion of dual-fuel is relatively stable. The exhaust temperature of DMDF mode was lower than that of diesel mode at various altitudes. Compared with diesel mode, NOX and Soot emissions in DMDF model significantly decreased at different altitudes and working conditions.