Recently, Jatropha, a fast growing tropical plant, has caught the attention of researchers because the oil produced from Jatrpha is a non-edible. However, worse emissions, when using raw Jatropha oil in diesel engines, have been reported in the literature due to its higher viscosity and lower volatility. Therefore, it is necessary to find some way to reduce the emissions of diesel engines. In the present research, experiments have been designed and performed to study the effects of Jatropha hydrogen peroxide emulsion on combustion, performance, and the emission characteristics of a diesel engine. Hydrogen peroxide in a solution of water at a concentration of 30% was used for making the emulsions with mixing mass ratios of 5%, 10%, and 15%. A single cylinder, four-stroke, high speed, direct injection diesel engine was used for the experiments. The acquired data were analyzed for various combustion parameters such as in-cylinder pressure, ignition delay, ignition duration, heat release, for performance parameters and emissions of CO, CO 2 , HC, NOx, and PM as well. While running the engine on the Jatropha hydrogen peroxide emulsion fuel, improvements in performance and emissions were found and the optimum mixing ratio of the solution with hydrogen peroxide was 15%.

a b s t r a c tThe experimental study was carried out using a four-stroke, high speed, DI (direct-injection) diesel engine with double fuel injections. In this study, Jatropha water emulsion was made by mixing a mass ratio of 10% of water. While fixing the first injection timing, we tested the engine on JWE (Jatropha water emulsion) with various injection timings and quantities of second injections. The acquired data was analyzed for various combustion parameters such as heat release rate, combustion center (timing of 50% of total heat release), ignition delay, and combustion duration; for performance parameters such as incylinder temperature, exhaust gas temperature, brake thermal efficiency; and emissions of CO (carbon monoxide), CO 2 (carbon dioxide), HC (hydrocarbons), NOx (nitrogen oxides), as well as dust and smoke opacity. When using a large second injection amount, we found a significant reduction in the peaks of the in-cylinder pressure, HRR (heat release rate), and average in-cylinder temperatures. We also found a drastic increase in the ignition delay, combustion duration, and a shift in the combustion center toward the later combustion stage, as well as increased exhaust gas temperatures, and reduced brake thermal efficiency compared with those of the Light oil. A large second injection amount reduced NOx emissions up to 48%, and drastically reduced HC emissions at higher loads of the engine.

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