Numerical simulation of a heavy-duty diesel engine to evaluate the effect of fuel injection duration on engine performance and emission

Abstract

Due to limited space in transport vehicles, compression ignition (CI) engines with high power density have always been a priority. In heavy-duty diesel engines, direct injection results creation of the lean region in the space of the combustion chamber. Increasing the fuel penetration by changing injection duration is an effective solution to achieve a homogenous mixture. In this paper, the impact of changing injection duration in upgraded MTU-4000-R43L diesel engine on power characteristics, rate of heat release (RoHR), combustion phasing, emission and, most importantly, the gradient of pressure changes as a characteristic of the vibration and knocking of the engine, has been studied numerically. Numerical simulation is performed in AVL Fire which is coupled with reduced detail chemical kinetics. The fuel injection duration was varying from 14.6 to 35.6 oCA, the in-cylinder mean pressure, the IMEP decreases, and the ISFC increases; however, as the fuel injection duration decreases, the pressure gradient rises; from the range of 30.6 degrees onwards, the reduction of the fuel injection duration leads to a severe knock of the engine and as a result reduces its engine life. Emission results also showed that CO2 and NOx increased and CO reduced with decreasing fuel decreasing injection duration.