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The use of diesel engines is increasing rapidly thanks to their superior fuel economy, higher efficiency and excellent reliability. The energy crisis of fossil fuel depletion, rising price of diesel and environmental degradation have triggered a search for clean, sustainable and alternative fuels for internal combustion engines. Biodiesel is one of the most promising and demanding alternative fuels because it is a biodegradable, non-toxic and renewable fuel. In the present work, an experimental investigation on the effect of injection timing on engine performance, emissions and combustion characteristics with coconut oil methyl ester (CME) was conducted in a high-pressure common-rail direct injection diesel engine. The tests were performed at constant speed of 2000 rpm and 50% throttle position operation. The test fuels included baseline diesel fuel and two different fuel blends of CME (B20 and B40).

Hydrogen internal combustion engine is considered as a suitable pathway to hydrogen economy before fuel cell technologies become more mature and cost effective. In this study, hydrogen combustion in a spark ignited direct injection (DI) engine that was optimized for natural gas application was studied. The performance characteristics such as the torque, power, BSFC were measured and analyzed for engine speeds of 1800 to 4000rpm. The combustion parameters such as the heat release were also analyzed and compared to natural gas operations. In general, the combustion of hydrogen was found to be less dependent on engine speed in comparison to compressed natural gas (CNG). It was found that low speed operation (engine speed below 2000rpm), the hydrogen combustion gave higher power output compared to CNG, owing to the more complete combustion. At higher speed, however, the performance dropped significantly due to the retarded ignition timing required to suppress pre-ignition.