A quasi-dimensional model of multiple-cycle fuel film evaporation in a port fuel injection spark-ignition methanol marine engine

For a port fuel injection (PFI) spark-ignition (SI) methanol marine engine, the proportion of residual methanol (Xf) depending on the fuel film evaporation (FFE) plays a crucial role in the fuel-air mixing process, combustion performance and emissions. Therefore, a quantitative assessment method on quasi-steady-state FFE was proposed and implemented to calculate the Xf, which was utilized to develop a novel FFE model aimed at improving the predictability of engine simulation. Then, the impact mechanism of injection timing on the engine's performance and emissions under different intake pressure conditions was revealed utilizing the Xf. Delaying the end of injection timing from −400°CA to −180°CA resulted in an early decrease of Xf, and then began to increase after the Xf reversal point. The shortest combustion duration (CA10-90) and the largest brake thermal efficiency (BTE) were achieved at higher Xf levels. Furthermore, optimizing injection timing could reduce HC and NOx emissions by up to 42.38 % and 48.54 %, respectively, though such adjustments need to be carefully tailored to different loads. Finally, a 1-D engine simulation incorporating the FFE model has been constructed and successfully replicated the effects of fuel film evaporation on engine combustion.