Energy-based cold-start strategies for diesel engines at extreme low temperature

Abstract

The cold start of diesel engines at extreme low temperatures is currently one of the most critical problems in the field of transportation. An experiment on the cold start was conducted in a controlled environment, and a one-dimensional simulation model was built to study diesel engine cold start performance based on energy analysis. The cyclic energy loss of cold start failure and success cases, ramp-up-speed period characteristic of diesel engine were studied by using special low temperature diesel and adopting two pilots and one main injection control strategy at −43 ℃. The numerical calculation and analysis results show that when the exhaust energy is high and the heat transfer loss energy is very low, there may be a misfire cycle in the cylinder. The increase in the pilot injection 1 mass, main injection mass, pilot injection 1 timing, and main injection timing within certain limits can significantly increase the fuel vapor fraction during the ramp-up-speed period (maximum of 66.67%). The speed of ramp-up-speed period and idle steady phase faster obviously, the maximum increase is 300 r/min (30%). The fuel vapor fraction increases as the pilot injection 2 mass increases during the ramp-up-speed period but slows down the speed of ramp-up and idle phase, with a maximum decrease of 300 r/min (23.07%).