Development of methods for adapting diesel engines to biodiesel fuel compositions

Abstract

Many publications have shown that, with some degradation of a diesel engine's power and economic performance, using fuel compositions containing vegetable oil ethers significantly reduces the toxicity of engine exhaust gases. Our experimental research into the motor qualities of mixture fuel have shown that increasing the volume share of the biological component of binary fuel slowly degrades the energy indicators of a diesel engine and improves its ecological features. In so doing, engine exhaust gases toxicity is not reduced drastically. The main goal of the research effort was increasing the energy and ecological indicators of a biodiesel engine by improving the methods of its adaptation to biodiesel fuel compositions. The task of the investigation was a comprehensive experimental validation of such methods. A theoretically substantiated method of compensating for diesel effective power losses was suggested by changing to fuel mixture supply. The method consists in increasing the energy content of engine cylinders by increasing the maximum fuel injection rate. Experiments have proved that increasing biodiesel engine power does not degrade ecological indicators considerably. These indicators are better than similar ones of a diesel prototype as to the level of emission of exhaust gases (EG) for carbon oxide and carbon dioxide by 36% and 11%, respectively; for nitrogen oxides, by 18%; for unburned carbon, by 7 times, and for EG smoke opacity, by 28%. Analysis of publications and preliminary estimates and experiments have defined actions to be taken to reduce the content of nitrogen oxides and solid particles in the exhaust gases of a diesel engine running on mixture fuel. The actions are to shorten fuel injection advance and use lean fuel-and-air mixtures. Experiments have shown that optimising the fuel injection advance angle and the minimal value of the air ratio improves dramatically (up to 50-80%) the ecological performance of a biodiesel engine. The new methods of improving the energy and ecological indicators of a biodiesel engine have confirmed experimentally their high effectiveness. Besides, these methods have a regulating character, making their implementation easier and cheaper.