| The use of oxygen-containing fuel partially replaces diesel is one of the effective means to solve the energy shortage and environmental pollution.Polyoxymethylene dimethyl ether(PODE)is a new type of coal-based oxygen-containing fuel,which has a wide range of synthetic sources,high cetane number,and high oxygen content and mutual solubility with diesel.PODE has great potential to realize clean combustion in diesel engine,and it is a kind of alternative oxygenated fuel for diesel engine with good application prospect.In this paper,the effects of different blend ratio of PODE/diesel blended fuel on the economy,combustion characteristics and emission characteristics of diesel engines were studied by means of the combination of experimental and numerical simulation.In this paper,PODE/diesel blended fuel was prepared according to the volume fraction of10%,20%and 30%PODE in the blended fuel,and was formulated as P10,P20 and P30 blended fuel.The miscible stability of PODE/diesel blended fuel with different proportions was studied.The physicochemical properties of blended fuel were analyzed.The volatile characteristics of PODE/diesel blended fuel were analyzed by Thermogravimetric Analyzer.The results show that PODE/diesel blended fuel have good miscible stability at room temperature and the evaporation characteristics were improved.The effect of PODE/diesel blended fuel on combustion and emission characteristics was investigated on a common rail diesel engine.The results show that:compared with diesel,the effective thermal efficiency increased,but the fuel consumption of PODE/diesel blended fuel increased,the ignition point advanced,the ignition delay period shortened,the maximum cylinder pressure increased,the combustion speed was improved.CO,HC emissions and exhaust smoke decreased,and with the increase of blend ratio of PODE,the decrease amplitude is greater.NO_x emission increased with the increase of PODE blending ratio.The number of peak particles increased,the particle mass median diameter decreased,and the particle quantity distribution, particle mass density distribution and particle mass distribution of PODE/diesel blended fuel were moved to small diameter direction,and with the increase of blending ratio of PODE,the trend of movement is more significant.The model of combustion chamber of diesel engine was established by using ESE module in AVL FIRE software,and the calculation parameters and boundary conditions were set up.After verifying the accuracy of the model,the effect of PODE/diesel blended fuel on the working process in the cylinder was analyzed.The results are as follows:The maximum combustion temperature in the cylinder increases after PODE addition,the distribution range of high temperature area in the cylinder increased,the range of distribution of oxygen atom in the cylinder increased.The NO generated in advance,and the concentration of NO increased,SOOT generation and distribution range of SOOT decreased with the increase of PODE blended ratio. |
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