Comparative performance and emission characteristics of peanut seed oil methyl ester (PSME) on a thermal isolated diesel engine

Highlights: • Application of the boronizing to a cylinder liner as a thermal barrier layer is novel. • Engine was coated 150 μm Fe₂B and 300 μm (CoNiCrAlYttra + NiCrBSi) isolation layers. • 3-D finite elements transient-state thermal analysis is done for both engines. • Performance of D-2 and biodiesel blends on coated engine showed some improvements. • Emissions of D-2 and biodiesel blends on coated engine decreased, except NOx. -- Abstract: In this research, cylinder liners of a diesel engine were coated with a 150 μm thick Fe₂B layer using boronizing method. The upper surface of the piston was coated with a 300 μm thick CoNiCrAlYttra + NiCrBSi layer by using plasma spraying method. D-2, biodiesel (PSME-100) and blend (PSME-50) were used as test fuels. PSME fuel was produced through alkali catalyzed transesterification method. As-prepared fuels were used separately in coated (CE) and standard engines (SE) to compare performance and exhaust emission of both engines. In order to see the isolation effect of Fe₂B layer, 3-D finite element transient-state analyses were carried out. According to the results, brake thermal efficiency (BTE) and exhaust gas temperature (EGT) of coated engine were considerably enhanced while brake specific fuel consumption (BSFC), CO, HC and smoke emission were decreased compared to those of standard engine. However, NOx emission of CE was higher than that of uncoated one, which was attributed to high combustion temperature and long combustion process in CE. These results were further confirmed with finite element simulation. The decreasing BSFC and increasing BTE for coated engine has been attributed to the elevated temperature of the combustion chamber by the effect of thermal insulation.