Research On Combustion And Emission Characteristics Of The Diesel Engine Burning Vegetable Oil

As the problems of fossil fuels depletion and the environmental problem caused by the internal combustion engine exhaust are getting worse and worse, how to make most use of alternative fuels in a intermal combustion engine has become one of the new hot topics in the automotive industry. In this paper, the diesel engine burns two kinds of vegetable oil on the condition that its structure parameters are not changed, these two kinds of vegetable oil are tung oil and camellia oil. Combustion characteristics, emission characteristics, economy characteristics, dynamic performance, cold start performance of the vortex diesel engine burning tung oil and camellia oil are explored in this paper; It compares the cylinder pressure, fuel consumption rate, smoke and NOx emissions generated by S195-1 vortex diesel engines and ZS195 direct injection diesel engine when both diesel engines was fueled with pure tung oil. This article selects three kinds of blended fuels. The first kind of blended fuel is vegetable oil-diesel, the proportion of vegetable oil is minor(10%,20%,30%);The second kind of blended fuel is butanol-ethanol-vegetable oil, the proportion of vegetable oil in the blended fuel is 85%; The third kind of blended fuel is pure vegetable oil.When diesel engine ran at the middle load condition points, according to the experimental results, we come to the following conclusions:First, compared with the combustion starting point of diesel engine burning pure diesel, the starting points of diesel engine burning the first kind of blended fuel generally lag 1℃A～2℃A; When 10% ethanol was added to the vegetable oil, the hysteresis phenomenon of combustion starting point of the butanol-ethanol vegetable oil mixed fuel is more obvious, it’s about 4℃A～5℃A. Second, compared with the peak of instantaneous releasing heat rate generated by diesel engine burning pure diesel, the peaks of instantaneous releasing heat rate generated by diesel engine burning these three kinds of blened fuels drop about 3.4%～10.56%.Third, when the engines burns these three kinds of blended fuels, the cylinders’internal pressure peaks are less than that generated by diesel engine burning pure diese, and the phases corresponding to cylinders’ internal pressure peaks are later that of diesel engine burning pure diesel, the biggest drop cylinders’internal pressure peaks reached 3.4%. When diesel engine ran at the high load conditions, we come to the following conclusions: First, the combustion starting points of diesel engine burning above-mentioned three kinds of blended fuels are the same as the combustion starting points of diesel engine burning pure diesel. Second, compared with the peak of instantaneous releasing heat rate of diesel engine burning pure diesel, the peaks of instantaneous releasing heat rate of diesel engine burning these three kinds of blended fuels are less. The peak of instantaneous releasing heat rate of the first kind of blended fuel could decrease by 5.64%, the peak of instantaneous releasing heat rate of the second kind of blended fuel could decrease by 8.23%, The peak of instantaneous releasing heat rate of the third kind of blended fuel could decrease by 11.46%.Third, when the engine burns any kind of above-mentioned blended fuels, the cylinders’ pressure peaks are less than that generated by diesel engine burning pure diesel, the cylinder pressure peak could decrease by 3.08%, and the phases corresponding to cylinders’ internal pressure peaks are the same as that of diesel engine burning pure diesel.When it comes to emission characteristics, tung oil and camellia oil can reduce diesel smoke effectively. As the proportion of vegetable oil in mixed fuels increases, smoke decreases. When diesel engine combusted pure vegetable oil, smoke emission could reduced by 69%. As for NOx emissions, the NOx emission of diesel engine burning the first kind of blended fuel is slightly less than the NOx emission of diesel engine burning pure diesel; However, when the engines burned the second kind of blended fuel or the third kind of blended fuel, its NOx emission decreased dramatically, which could be reduced by 34.3%.When burning vegetable oil, the power performance of diesel engine could achieve the dynamic performance of the original machine, but its fuel consumption rate is greater than that of diesel engine burning pure diesel, which can increase by 29.5%; and its cold start performance decreased slightly. When vortex diesel engine and direct injection diesel engine both burn pure tung oil, the differences of their performance are mainly as follows:First, at high load conditions, the maximum combustion pressure generated by vortex diesel engine is less than that generated by direct injection diesel engine. Second, when both these two kinds of diesel engines burn pure tung oil, at all of tested operating points, smoke of vortex diesel engine is more than the smoke of direct injection diesel engine, NOx emission of vortex diesel engine is less than the NOx emission of direct injection diesel engine.