Study Of Bio-diesel In Compression Engine

The study of alternative energy sources has already been developed all over the world because most of the countries in the world must encounter the difficulty of the energy sources problem. Bio-diesel, as a renewable alternative fuel, has become more and more considered by the people.The main ingredient of bio-diesel fuel used in the experiment is the Soybean Metyl Ester. The three types of blend fuels are respectively made by adding 10%,20%,30% of bio-diesel fuel fraction to the petroleum diesel. Since the experiments were conducted between the blend fuels and the petroleum diesel, it can be concluded that the ratio of the bio-diesel in the petroleum diesel has an important effect on the engine combustion characteristics,performance and emission characteristics by the analysis of physical properties, indicator diagram, combustion, emission. The purpose is to choose the best ratio under the condition that the engine performance is not well influenced.Extensive experiments with the physical characteristics of fuels were carried out on a engine fueled with petroleum diesel and three kinds of bio-diesel fuels (B10, B20and B100).Through the experiments, it can be concluded that the density of the bio-diesel is higher than that of the petroleum diesel, and the density of blend fuel increases with the increasing of the ratio of bio-diesel in petroleum diesel; The calorie value contained in the bio-diesel is lower than that of the petroleum diesel, and the calorie value contained in the blend fuel decreases with the increasing of the ratio of bio-diesel in petroleum diesel; In these experiments, though the cetane of the bio-diesel is lower than that of the petroleum diesel , the ignition performance of the bio-diesel is well because its cetane is up to 48.3; The oxygen contained in the bio-diesel is much higher than that of the petroleum diesel, and the oxygen contained in the blend fuel increases with the increasing of the ratio of bio-diesel in petroleum diesel; Though the viscosity of the bio-diesel is higher than the petroleum diesel, it can meet the demand of the diesel engine; The flash point of the bio-diesel is obviously higher than that of the petroleum diesel, and the flash points of the blend fuels increase with the increasing of the ratio of bio-diesel in the petroleum diesel; All the distillation temperature(50%, 90%, 95%) of the bio-diesel used in the experiment are a little higher than that of the petroleum diesel, but the distinction is not obvious.From the results of the experiment, it can be concluded that, as the density of the bio-diesel is higher, the quality of the fuel injected in the cylinder during the same injection period increase without any configuration modification in the diesel engine, which contributes to improving the shortcoming of the bio-diesel whose calorie value is low; As the oxygen contained in the bio-diesel is much higher than that of the petroleum diesel, it can improve the shortcoming of the mixture gas formation in the diesel engine; The flash point is high, so it is convenient for transport and store. As mentioned in the paragraph, the bio-diesel as a kind of alternative fuels is suitable for diesel engine.Without any configuration modification of a turbocharged intercooled CI engine, the experiment fueled with four kinds of bio-diesel fuels (B0, B10, B20 and B30) has been conducted according to ECE R49 13-mode.The results of combustion characteristics show that the maximum combustion pressure, the mean indicated pressure and the power in the cylinder gradually decrease with the increasing of the ratio of bio-diesel in petroleum diesel. The trend become more obvious as the engine loads become smaller, and the corresponding crank angle at the maximum combustion pressure will delay; The ratio of pressure rise gradually decreases with the increasing of the ratio of bio-diesel in petroleum diesel, the distinction is not obvious; The maximum value of heat release of the blend fuels is lower than that of the petroleum diesel. The periods of ignition delay and the combustion duration gradually increase with the increasing of the ratio of bio-diesel in petroleum diesel at the same load and engine speed.The results of experiment show that the bio-diesel engine performance decreased a little compared to the petroleum diesel, but the changes of maximum torque and power are not obvious when using the B10.The changes can not have effect on the engine performance; As far as fuel consumption ,both the bio-diesel engine and blend fuel are higher than the petroleum diesel, but the distinction is not obvious. In a word, though the engine performance and fuel economy are a little dropped when used bio-diesel, the change is quiet a little.The HC emission used the bio-diesel and the blend fuel is far lower than the petroleum diesel, and the HC emission will become less and less with the increasing of the ratio of bio-diesel in petroleum diesel; The CO emission gradually decreases with the increasing of the engine load, but it increase a little just at large engine loads, especially at 2800r/min. The CO emission fueled with the bio-diesel and the blend fuels is lower than that of the petroleum diesel, and the decreasing extent become smaller with the increasing of the engine load; The NO_x emission used the bio-diesel and the blend fuel is lower than that of the petroleum diesel, however, the distinction is not obvious.