enhancing diesel combustion efficiency with multi-stage fuel injection: applications in maritime and heavy-duty agricultural engines

Diesel engines are extensively used worldwide, particularly in iran, for power generation, ship propulsion, and agricultural machinery such as tractors. this study examines the performance of a heavy-duty diesel engine by evaluating four different fuel injection rate models using computational fluid dynamics. results indicate that the triangular injection rate yields optimal performance, improving brake-specific fuel consumption by 5.5% and increasing peak combustion chamber temperature compared to other models. reducing the nozzle diameter from 330 to 190 microns enhances combustion efficiency and lowers carbon monoxide (co) emissions by 15%. shortening the injection duration to 2 milliseconds improves specific fuel consumption by 3.3%, reflecting better combustion performance. additionally, a spray angle of 147.5 degrees optimizes fuel-air mixing, leading to more complete combustion and minimal co emissions. finally, a 7.5% exhaust gas recirculation rate is identified as the optimal balance for reducing both soot and nitrogen oxides (nox) emissions.