Performance of a compression ignition engine fuelled with diesel-palm biodiesel-gasoline mixtures: CFD and multi parameter optimisation studies

In this research, 3D CFD simulations are conducted for a compression ignition engine fuelled with D100 (diesel), D80|BD20 (80%diesel|20%biodiesel), D75|BD20|G5 (75%diesel|20%biodiesel|5%gasoline), D70|BD20|G10 and D65|BD20|G15 mixtures. The effects of blending ratio, exhaust gas recirculation (EGR) and start of injection (SOI) on the combustion, emissions, engine output and fuel efficiency are analysed. In brief, D65|BD20|G15 produced the least nitrogen oxides (NOx) and soot emissions of 6.5E-2 and 5.46E-3 g/kWh, respectively, which were lower than the Euro VI limit. The least carbon monoxide (CO) and unburnt hydrocarbons (UHCs) emissions were achieved for D75|BD20|G5 for 1.62 and 5.8 g/kWh, respectively. D75|BD20|G15 improved the indicated mean effective pressure (IMEP), combustion efficiency and indicated specific fuel consumption (ISFC) up to 13.9%, 12.7% and 13.9% compared to D80|BD20, respectively. Also, applying 20% EGR led to 50% reduction in NOx and soot for D65|BD20|G15, while UHCs and CO were increased up to 27% and 54%, respectively and ISFC and combustion efficiency slightly declined. Additionally, advancing SOI timing to −24 Crank Angle (°CA) decreased the CO and UHCs emissions of D65|BD20|G15 up to 20% and 15% compared to −20°CA, respectively. A multi-parameter optimisation is also performed to ascertain the best operating condition, under which the emissions are mostly supressed and engine performance and fuel efficiency are enhanced.