Simulation Study On Low Temperature Combustion Performance Of Electronic Controlled Diesel Engine Mixed With Butanol

Due to the shortage of energy resources and increasingly stringent emission regulations,the engine energy conservation and emission reduction has become the research focus for internal combustion engine researchers.Finding alternative energy sources and developing new combustion modes are effective measures to achieve energy saving and emission reduction.Low temperature combustion mode can inhibit the formation conditions of NOx and soot emissions by decreasing combustion temperature.In addition,blending butanol in diesel fuel can improve the low temperature combustion characteristics by using the oxygen characteristics of butanol.In this paper,the combustion characteristics of diesel-butanol blended fuel were studied based on the electronic-controlled modified 4190 type diesel engine,and the combustion quality is optimized by changing injection pressure,injection timing and intake pressure.First of all,In order to improve the injection pressure of fuel injection system,the fuel injection system model of the electronic control unit pump was established by using AMEsim simulation software,and the accuracy of the model was corrected and verified based on the experimental data.In order to analyze the effect of fuel system parameters on the injection characteristics,the simulation of parameters of fuel injection system is designed by using orthogonal experimental based on the model.The results show that the influence degree of each parameter on the injection pressure from strong to weak in sequence is:diameter of plunger,diameter of,CAM shape liner velocity,number of orifice×diameter of orifice?flow area is unchanged?,length of high-pressure fuel pipe;It is not significant to change the effect of the injection pressure simply by changing the length or diameter of the high-pressure oil pipe on the basis of the constant flow area of the nozzle.Secondly,the burning in cylinder simulation model is established by using AVL_FIRE software,and choose the mechanism file of chemical reaction suitable for diesel-butanol mixed fuel to couple the software,then set the appropriate initial conditions,boundary conditions and sub module,finally verify the accuracy of the model by comparing the simulation value to the test value of the cylinder pressure curve.Thus the combustion model of diesel-butanol mixed fuel is established.Lastly,different injection pressure is achieved by coupling AMEsim and AVL_FIRE software,and the low temperature combustion is achieved by introducing the exhaust gas recirculation,so that the effect of the injection pressure?butanol mixing ratio?EGR ratio?fuel injection advance angle and inlet pressure on the performance of emissions and combustion of mixed fuel can be analyzed.Results indicate that increasing the injection pressure can improve the mixing uniformity of oil and gas and make the atomization effect better.After the introduction of EGR,the average combustion temperature in the cylinder can be reduced to less than 1650K,while the low temperature combustion is realized and the NO emission is significantly reduced.Blending butanol in diesel oil can obviously improve the low temperature combustion,which also can inhibit the formation of Soot and CO.The simulation results of the butanol-diesel blended fuel of B10 on 15%EGR ratio and B20 on 12.5%EGR ratio indicate that the increase of the fuel injection advance angle causes the increasing of the emission of NO,but emission of CO decreased significantly.Dynamic and economic performance improved significantly by increasing the intake pressure,while the emission of NO and CO decreses,but the mass fraction of soot precursor A₄ that converted to soot is increased.