Combustion and performance characteristics of a diesel engine fueled with coal-based hybrid fuel at various altitudes

At high altitude and low pressure, the changes of inlet and exhaust pressure and the combustion environment in the cylinder lead to the deterioration of physicochemical characteristics and combustion in the cylinder of the coal-based mixed fuel. In this research, based on the plateau environment simulation test platform, the combustion characteristics, dynamic performance and fuel economy of the turbocharged diesel engine burned at different simulated altitudes (0 m, 1500 m, 2500 m, 3500 m and 4500 m) were studied. The results revealed that as altitude increased, the coal-based composite fuel caused the diesel engine's in-cylinder pressure, pressure rise rate, and instantaneous heat release rate to gradually decrease, the flameout period to gradually extend, and the center of gravity of combustion to gradually delay. At low engine speed, the average effective pressure cycle variation rate increased significantly. The coal-based complex fuel diesel engine has increased in-cylinder pressure, torque, and effective thermal efficiency, as well as peak instantaneous heat release rate at high altitude, when compared to diesel combustion. It also causes a reduction in the maximum pressure rise rate, a forward shift in the combustion center of gravity, a reduction in the average effective pressure cycle rate of change, and a shortening of the stall period.