EXERGY ANALYSIS OF DIESEL ENGINE FUELLED WITH BIODIESEL

Abstract

The present study relates to the exergy analysis carried out on a 4-stroke, single cylinder, variable speed, water-cooled direct injection diesel engine when fuelled with mineral diesel and biodiesels based on Waste Cooking Oil (WCO) and Neem Oil. The influence of speed, load, and biodiesel blends on various exergetic parameters have been studied. The study was accomplished in five phases. In the first phase exergy analysis of engine fuelled with mineral diesel fuel was carried out and the influence of speed and load on the exergetic parameters was studied. It is observed that with increase in load torque, the exergy destruction percentage reduces, that results higher exergetic efficiency. In the second phase, experiments were carried out with five biodiesel blends of each biodiesel fuel based on WCO and NEEM. The influence of engine speed, load torque, injection timing on BSFC, brake thermal efficiency and various exergetic parameters was determined. It is observed that lower percentage of biodiesel in the fuel blend gives the lower exergy destruction and high exergetic efficiency as compared to that of higher blends of each biodiesel. As the biodiesel percentage increases in the fuel blend, the brake thermal efficiency and exergetic efficiency decrease and exergy destruction increases. In the third phase, experiments were conducted to determine the influence of advanced injection timings on the exergetic parameters. It is observed that by advancing the injection timing by 20 crank angle degree (CAD), the BSFC decreases and brake thermal efficiency increases. The exergy parameters namely exergetic efficiency, sustainability index, exergy performance coefficient, exhaust exergy increase and exergy destruction decrease. However, further advancing the injection timing deteriorates the performance. Optimization of engine operating parameters (Speed and load) and injection system parameters (injection timing and pressure) for minimum exergy destruction was carried out in phase four. Multiobjective optimization approach was applied to get the optimum level of parameters for lower exergy destruction, lower BSFC, higher exergy performance coefficient, and higher exergetic efficiency. Taguchi methodology based on the orthogonal array was used for experiment design. In the fifth phase, the influence of Diethyl ether (DEE) as an additive on the exergy parameters of test engine fuelled with methyl ester of waste cooking oil and neem oil was investigated experimentally. It is found that higher percentage of DEE improves the engine performance from the energy and exergy point of view. Lower exergy destruction, higher exergy performance coefficient, low entropy generation, high exergertic efficiency and high sustainability index based on the exergetic efficiency is observed with 15% DEE addition.