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 (degrees CA) decreased the CO and UHCs emissions of D65|BD20|G15 up to 20% and 15% compared to -20 degrees 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.

Automated summary

CFD simulations were conducted to study the effects of fuel blending ratio, exhaust gas recirculation (EGR), and start of injection (SOI) on the combustion, emissions, engine output, and fuel efficiency of a compression ignition engine. The results showed that the D65|BD20|G15 mixture achieved the lowest nitrogen oxides (NOx) and soot emissions, while the D75|BD20|G5 mixture had the lowest carbon monoxide (CO) and unburnt hydrocarbons (UHCs) emissions. The application of 20% EGR reduced NOx and soot, but increased UHCs and CO emissions. Advancing the SOI timing decreased CO and UHCs emissions. A multi-parameter optimization was performed to determine the best operating condition.