Optimization of the low-load performance and emission characteristics for a heavy-duty diesel engine fueled with diesel/methanol by RSM-NSWOA

Abstract

In this paper, the renewable energy, methanol, used as alternative fuel for diesel engine was systematically investigated under low load. The effect of different methanol fractions (MF) on diesel-methanol dual-fuel (DMDF) combustion, emission and performance is explored. Results shows that the net indicated efficiency (NIE) of DMDF is 2.4 % higher than that of conventional diesel combustion (CDC) when the MF increased to 60 %, although the combustion efficiency is decreased. The higher MF can also produce less NOX and smoke with higher HC and CO emissions. Then, exhaust gas recirculation (EGR) was added to further optimize the DMDF operation under MF of 60 %. A comparison analysis shows that the DMDF with 26 % EGR improve the NIE and NOX emission by 3.5 % and 87 %, respectively compared to CDC. Finally, the NOX, BSFC and combustion efficiency of DMDF were further optimized based on response surface method (RSM) and non-dominated sorting whale optimization algorithm (NSWOA). It is found that there is a strong trade-off among them. In order to obtain lower NOX emissions and BSFC simultaneously, the combustion efficiency has to be compromised. Finally, the NOX and BSFC of optimized DMDF are reduced by 53.42 %, 5.37 % respectively when compared to the previous experimental results.