Engine performance and emission characteristics of microwave-produced biodiesel blends

The main objective of this research is to investigate, experimentally, the effects of biodiesel blends on the performance and emissions of a diesel engine. Measurements were carried out on a single-cylinder, four-stroke, and air-cooled compression-ignition engine, under half and full load conditions. Engine speed was varied from 1000 to 3000 rpm. Biodiesel was produced by transesterification process of sunflower oil with ethanol, using microwave-assisted heating reactor. Three biodiesel-diesel mixtures: containing 5%, 10% and 20% by volume of biodiesel, respectively, have been tested and compared to pure diesel fuel. The effects of these biodiesel blends on the engine operating characteristics such as brake specific fuel consumption, brake power, brake thermal efficiency, brake mean effective pressure and on carbon monoxide, carbon dioxide and nitrogen oxides emissions, have been investigated. It was noticed that, at full load, the specific fuel consumptions of biodiesel blends were higher compared to the pure diesel fuel, but no change was observed under 1/2 load. An improvement in the brake thermal efficiency, under 1/2 load, was obtained, but at full load, for medium and high-speed, the thermal efficiencies of all biodiesel blends showed a decrease compared to pure diesel fuel. Concerning pollutants emissions, a decrease in carbon monoxide emissions of all biodiesel blends was noticed. The best result in carbon monoxide emissions was achieved by the mixture containing 10% by volume of biodiesel with an average reduction value close to 40%. In addition, a significant reduction in nitrogen oxides emissions was observed for the three biodiesel blends.