Analysis of pre-injection rate effects on combustion, performance, and emissions in a JP8-fueled PPCI engine

In this study, the effects of varying pre-injection rates (10%, 20%, 30%, 40%) on engine performance, combustion efficiency, and emissions were investigated in a partial premixed compression ignition (PPCI) engine using JP8 fuel at various loads (0%, 25%, 50%, 75%, and 100%) and compared with diesel fuel. A 10% pre-injection rate was most effective in maintaining fuel efficiency across loads, showing the lowest BSFC values. At 50% load, the 10% rate resulted in a brake specific fuel consumption of 294.22 g/kWh, only 9.69% higher than diesel. Higher rates (30% and 40%) increased fuel consumption and decreased efficiency. Combustion efficiency and CO2 emissions improved with 20% and 30% rates, especially at high loads. At 75% load, 30% pre-injection increased CO2 emissions to 8.827%, exceeding diesel 7.88%, indicating better combustion. Soot emissions decreased significantly with 30% and 40% rates, but NOx emissions rose substantially, with the 40% rate reaching 1448 ppm at full load. The 10% rate was deemed optimal for balancing efficiency and low emissions, while higher rates, though beneficial for combustion and soot, require measures to mitigate NOx emissions.