Albizia lebbeck leaf extracted natural antioxidant doped biodiesel–diesel blend in low heat rejection diesel engine

Abstract

Natural antioxidants are available in various biomass substances which can be used for improving human health and fuel oxidation stability. This research is aimed at using a natural antioxidant powder obtained from Albizia lebbeck leaves powder to improve the oxidation stability of an optimal Jatropha methyl ester (JME)-diesel blend. Initially, Albizia lebbeck leaves are characterized by x-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy for their oxidant behavior. The optimal JME diesel blend (JME20) has a mixture of 20% JME and 80% diesel. The antioxidant at different concentrations, viz., 500, 1000, 1500, and 2000 ppm, is doped in JME20, and the blends are designated as AL1, AL2, AL3, and AL4, respectively. The test engine is converted to run on the low heat rejection (LHR) mode by coating the piston with a mixture of two different ceramic materials, i.e., yttria-stabilized zirconia and cerium oxide (CeO2), with a thickness of 0.3 mm of the topcoat and 0.15 mm of the bond coat of material NiAl. The emissions, performance, and combustion of the test engine run on antioxidant-doped JME20 fuels in conventional engine operation and LHR mode are evaluated, analyzed, and presented in this paper. Results indicate that, among the four antioxidant-doped JME20 fuels, JME20AL4 gives better performance and lower exhaust emissions. The engine's cylinder pressure and heat release rate are decreased by about 4.7% and 6.4%, respectively, at full load, for JME20 AL4. The delay period and combustion duration of the fuel are improved by about 26.8% and 10.8%, respectively, at maximum load. The NO, HC, and CO emissions are reduced by about 17.3%, 19.3%, and 44.2%, respectively, for JME20 AL4, at maximum load.