Effect of synthetic antioxidant-doped biodiesel in the low heat rejection engine

Abstract

Thermal barrier coated (TBC) engines are used to increase engine performance and reduce emissions, but they increase NOx emissions. Biofuels can be doped with different types of antioxidants or additives to reduce NOx emissions and improve engine performance. In this investigation, N-isopropyl-N′-phenyl-1, 4-phenylenediamine (IPPD) is used as an antioxidant. IPPD at different concentrations, viz. 500, 1000, 1500 and 2000 ppm, was mixed with Jatropha methyl ester (JME) and the mixtures were tested as fuels in a TBC piston assembled engine. The piston crown is coated with a mixture of yttria-stabilized zirconia (YSZ) and cerium oxide (CeO2) with a thickness of 0.3 mm. The TBC piston is assembled in a single-cylinder, four-stroke, naturally aspirated, direct injection (DI), constant speed diesel engine for the investigation. The brake thermal efficiency (BTE) is higher by 18.8% than that of the conventional engine, and the brake-specific fuel consumption (BSFC) is lower by 11.7%. Unburnt hydrocarbon (HC), carbon monoxide (CO) and smoke emissions are lower by about 23.4%, 22.9% and 23.5%, respectively, at maximum load, after doping with the antioxidant compared with the JME-fueled conventional engine. Nitric oxide (NO) emission was reduced by 8.9% at maximum load for JME doped with 1000 ppm antioxidant.