What is the thermal efficiency of a diesel engine?
1 Answers
Diesel thermal efficiency refers to the ratio of effective output energy to input energy for a specific thermal energy conversion device. It is a dimensionless indicator, generally expressed as a percentage. The thermal efficiency of diesel engines can reach 35%-45%. The advantages of diesel engines are high torque and good economic performance. Each working cycle of a diesel engine also goes through four strokes: intake, compression, power, and exhaust. However, since the fuel used in diesel engines is diesel, which has higher viscosity than gasoline and is less volatile, its auto-ignition temperature is lower than that of gasoline. The formation of the combustible mixture and the ignition method are different from those of gasoline engines. In diesel engines, the mixture in the cylinder is compression-ignited rather than spark-ignited. During operation, air enters the cylinder. When the air in the cylinder is compressed to the end point, the temperature can reach 500-700°C, and the pressure can reach 40-50 atmospheres. As the piston approaches top dead center, the fuel injector of the fuel supply system injects fuel into the cylinder combustion chamber at extremely high pressure within a very short time. The diesel forms fine oil particles, mixes with the high-pressure and high-temperature air, and the combustible mixture ignites spontaneously.
