Numerical Simulation Research On The Combustion And Emission Characteristics Of Ethanol/Biodiesel/Diesel Mixed Fuel

With the rapid development of all walks of life in China,the shortage of fossil energy and environmental pollution are becoming increasingly serious,so the development of alternative energy is of great significance.Ethanol and biodiesel are not only renewable energy,but also blended with ethanol or biodiesel can effectively improve the combustion process and particulate emissions of diesel engine,so as to alleviate the pressure of energy shortage and reduce environmental pollution,which has great theoretical significance and application prospects.In this paper,the combustion and emission characteristics of ethanol/biodiesel/diesel blends with different ratios were studied by experiment and data simulation.Through theoretical analysis and miscibility test,the miscibility data of ethanol,biodiesel and diesel at different temperatures were obtained.According to the experimental data,five schemes of BD100,BD75,BD72E3,BD70E5 and BD65E10 were developed.The stability of the scheme was verified by static test,and some important physical and chemical properties of the blended fuel were measured,It provides data parameters and basis for numerical simulation research and analysis.The 3D model of combustion chamber is established by Catia software,and mesh module is used for Mesh generation.Then the numerical simulation software Fluent is used for numerical simulation of five kinds of fuel.The accuracy of the model is verified by comparing the engine bench test data with the simulation results.The Sauter mean diameter,fuel growth process,in cylinder pressure,in cylinder temperature,NOx and soot emissions of five kinds of fuel were simulated and compared.The simulation results show that:large proportion of biodiesel makes the viscosity,density,surface tension and other physical and chemical parameters of the blended fuel increase,resulting in poor atomization quality of the fuel in the cylinder,but adding ethanol not only improves the atomization quality,but also improves the combustion process of the fuel in the cylinder,and the fuel combustion is more full and thorough.After adding biodiesel and ethanol,the maximum pressure in the cylinder increases.Compared with 0#diesel BD100,the maximum in-cylinder pressure of mixed fuel BD75,BD72E3,and BD70E5increased from 13.6624MPa of 0#diesel BD100 to 13.7735MPa,13.8846MPa,.13.9728MPa and14.2924MPa;The crankshaft angle corresponding to the combustion starting point moves forward,from 355℃A to 353℃A,353.5℃A and 354℃A respectively,and the crankshaft angle corresponding to the combustion starting point of fuel BD65E10 moves backward,which is 356.5℃A;The overall average value of NO_Xemissions increased 3.947%,4.578%,6.54%,6.812%respectively when the speed n=2200r/min,and 2.678%,1.246%,3.584%,4.77%when the speed n=3600r/min;Soot emissions are reduced,when the speed n=2200r/min,the average reduction rate is 2.019%,7.168%,19.202%,39.666%;when the speed n=3600r/min,the average reduction rate is 1.19%,7.446%,15.362%,31.81%.