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Abstract
Due to the rapid decline in crude oil reserves, the use of vegetable oils as diesel fuels is again promoted in many countries. Depending upon climate and soil conditions, different nations are looking into different vegetable oils for diesel fuels. Experiments have been performed to determine the optimum conditions for the preparation of methyl ester of waste vegetable oil [MEWVO], namely, room temperature 25°C; 0.5-0.6 % sodium hydroxide catalyst by weight of waste vegetable oil; stirring time 60 minutes, agitation was not necessary after the reaction mixture became homogeneous; absolute methanol was necessary for high conversion. 50% excess methanol with NaOCH3 gave a maximum conversion. Density, viscosity, calorific value, and Cetane No. of the MEWVO were measured.
The waste oil biodiesel was then used to prepare biodieseVdiesel blends. The first part of experiments using this waste oil biodiesel have been performed on a four-stroke, two-cylinder, direct injection diesel engine of agricultural tractor for the blends BO (pure diesel) and B20 (20% biodiesel and 80% diesel). Engine performed well in all conducted tests when fueled with biodiesel blend 20%. Reduction of exhaust pollutants are observed with increasing the percent of biodiesel in the blend. The second part of experiments have been performed on a four strokes, six cylinder, direct injection, and naturally aspirated Diesel engine when operating on 5% (5% biodiesel), 10%, 20% and 30% blends with Diesel fuel. At a higher speed of 1800 rpm, the bsfc of the fully loaded engine for the B20 blend is nearly the same as that for diesel fuel, whereas B30 suggest the bsfc is higher by 11.65%. The results indicated that higher than 10 % by vol. of biodiesel in diesel fuel lowers the fuel energy conversion efficiency for the biofuel. Emissions of NOx appear to increase with increasing biodiesel concentration in the blend, and at the highest load point, the biggest CO emission of .08 % by vol. was measured for Diesel fuel, and the lowest of .05 % by vol. was obtained for blend B30, indicating more complete combustion with increasing biodiesel concentration in the blend due to its oxygenated nature. Jatropha oil biodiesel and other source of waste oil biodiesel fuels were produced to operate a four-stroke, single cylinder, and direct injection (type: TecQuipment TD43F) variable compression ratio diesel engine. For both jatropha and waste oil biodiesel fuels, the percentages of biodiesel were tested are: 10010 (BI0), 20% (B20), and 30% (B30), 50% (B50) In addition, pure diesel fuel (BO) was tested to establish the 0% biodiesel point. The emission and performance tests were perfonned at a compression ratio of 18 for jatropha oil biodiesel and at compression ratios of 14, 16, and 18 for waste oil biodiesel at engine speeds ranging from 1000 to 2000 rpm, increasing in 250 rpm increments at fully opened throttle conditions for each speed. The results referring to the engine’s brake power and torque showed that the B50 fuel blend resulted in lower brake power and torque relative to the baseline fuel for all blends of both jatropha and waste oil biodiesel fuels. There were about 2.72, 2.3, 4.08, and 7.12% higher specific fuel consumption as an average value for the three compression ratios when running on waste oil biodiesel blends B 10, B20, B30, and B50 -than diesel fuel at 2000 rpm respectively. The brake thermal efficiency and the exhaust ps temperature of all biodiesel blends were lower than that of pure diesel. Emissions of CO and HC were reduced and the NOx emissions were increased as the concentration of
biodiesel was increased at all compression ratios for both types ofbiodiesel fuels used.