Effect of pilot injection timings on the combustion temperature distribution in a single-cylinder ci engine fueled with DME and ULSD

Many studies of DiMethyl Ether (DME) as an alternative fuel in Compression-Ignition(CI) engines have been performed. Although diverse DME engine research has been conducted, theinvestigation of combustion behavior and temperature distribution in the combustion engine has notprogressed due to the fact that there is no sooting flame in DME combustion. In order to investigatethe combustion characteristics in this study, the KIVA-3 V code was implemented to research variouspilot injection strategies on a single-cylinder CI engines with DME and Ultra-Low-Sulfur Diesel(ULSD) fuels. The combustion distribution results obtained from the numerical investigationwere validated when compared with the measurement of flame temperature behaviors in theexperimental approach.This study showed that long intervals between two injection timings enhanced pilot combustion byincreasing the ambient pressure and temperature before the start of the main combustion.Different atomization properties between DME and ULSD fuels contributed to the formation ofa fuel-air mixture at the nozzle tip and piston lip regions, separately, which strongly affected thetemperature distribution of the two fuels. In addition, the pilot injection timing played a vital rolein regard to ignition delay and peak combustion temperatures. Exhaust emissions, such as NOxand soot, are related to the local equivalence ratio and temperature in the combustion chamber,also illustrated by the contrary result on a Φ (equivalence ratio) – T (temperature) map.