Effects of pilot injector specifications on combustion and emissions of diesel-methanol dual-fuel direct injection engine

Abstract

Diesel-ignited methanol direct injection engine can achieve high methanol substitution rate and low emissions. The effects of pilot diesel injector specifications, including hole number and installation location, on the combustion and emissions of a diesel-methanol dual-fuel direct injection engine were investigated in this study. The results show that increasing the number of diesel injection holes reduces the proportion of methanol premixed combustion, which is beneficial to reducing ringing intensity (RI) and reducing pollutant emissions. Different pilot injector types and installation positions have a significant impact on the combustion mode of methanol, but have little impact on fuel economy. The equivalent indicated specific fuel consumption (EISFC) is below 165g/kWh in all cases. When the diesel ignition area deviates from the center of the cylinder, methanol mainly undergoes premixed combustion, and NO_X, HC, and CO emissions increase significantly. When the diesel combustion area is located in the center of the cylinder, methanol mainly undergoes diffusion combustion, with lower RI and less pollutant emissions.