The Research And Development Of Natural Gas Engine Adapts To Different Composition Fuels

In the wake of the seriousness of energy crisis and environmental pollution in the world, finding clean new energy sources used in engine have become a hot spot in automotive research area nowadays. So far, CNG is the most practical and natural developmental clean alternative of engine. The storage of Chinese natural gas is abundant. In recent years, CNG vehicle developed quickly. But there are still some problems. The sources of domestic natural gas are more distributed. Different areas, different mine have different composition gas, which changes with seasons and can not be predicted. The range of CNG compositions limited by related regulations are wide relatively. So the qualities of domestic CNG used in engine are varied, which will impact the performance and exhaust of engine when different composition CNGs are as one engine fuels.In order to know the effect law of different composition CNGs on performance and exhaust of engine clearly and correct the fuels, the combustion processes of seven CNG samples were simulated and compared in this paper. First, I selected the lean-burn natural gas engine as experimental prototype, built the3D model of cylinder by CATIA. Then by using AVL-FIRE I simulated the combustion process from IVC to EVO. The correction of cylinder model was verified by comparing simulated results with experimental results. Secondly, I chose Methane as standard fuel, and added different proportional ethane, propane and butane with the same volume into methane fuel to form CNG samples respectively, then compared with standard fuel. The CNG samples with ethane are methane+3%ethane, methane+9%ethane, methane+16%ethane. The analytical conclusion is the more volume of ethane, the higher combustion pressure and temperature are, the larger initial mass fraction of fuel is, and the more CO and NO generated. The CNG samples with propane are methane+3%propane, methane+6%propane. The analytical conclusion is also the more volume of propane, the higher combustion pressure and temperature are, the larger initial mass fraction of fuel is, and the more CO and NO generated.Meanwhile, horizontal comparison of methane+3%ethane, methane+3%propane had been done. The six parameters of CNG sample with propane are higher than the ones of CNG sample with ethane. Then compared methane+0.7%butane with methane, the former is a little higher than the later. Finally, I summarized the variety low of maximum average pressure, maximum average temperature, maximum heat release rate, initial mass fraction of fuel, generations of CO and NO as C/H varying.In order to let the fuels of different qualities apply to the same engine, the paper proposes2fuel revise schemes. The first one, which is more effective in propane and butane, is to revise the mixture equivalence ratio of each component; the second scheme is to revise eachone’s combustion rate, namely the combustion potential, to make it unanimous with methane. The research of this paper in the fuel revise schemes proposes a principle for further research and development of its adaptive technologies.