Cold start performance of diesel engine at extremely low ambient temperatures and high altitudes: The superiority of premixing diethyl ether

The cold-start performance poses a primary challenge influencing the reliability of diesel engines operating in plateau and low-temperature regions. An experimental investigation was conducted to assess the cold-start performance of diesel engines with premixing diethyl ether (DEE), spanning altitudes from sea level to 4000 m and ambient temperatures of -20 degrees C and -40 degrees C. The diesel engine with premixing DEE exhibited successful cold starts at all these test conditions. In comparison, the diesel engine employing intake heating failed to reach idle speed in -40 degrees C high-altitude conditions. The premixed DEE could generate radicals, accompanied by a minor heat release preceding the injection of diesel, facilitating ignition. Furthermore, the premixed DEE enhanced fuel evaporation and facilitated the formation of combustible mixtures with higher equivalence ratios at low temperatures. Moreover, the fuel film resulting from wall impingement with premixing DEE was thinner than that with intake heating, contributing to decreased incomplete combustion losses. Energy analysis results revealed that the diesel engine employing premixing DEE demonstrated higher indicated thermal efficiency. The cold start assistance by premixing DEE proved to be much more effective, and the test engine could start smoothly under extremely low temperatures of -40 degrees C and high altitudes up to 4000 m.