| Energy conservation and environmental protection have always been the two major themes of the development of internal combustion engine technology.Diesel engines are widely used in transportation,engineering machinery,agriculture,military and other fields due to their low speed,high torque and high reliability.However,their high NO_X and PM emissions hinder the further development and application of diesel engines.Gasoline/diesel blends can significantly reduce PM emissions from diesel engines,but at the same time lead to increased NOx emissions.Exhaust gas recirculation(EGR)systems can significantly reduce engine NOx emissions.Therefore,the installation of an exhaust gas recirculation(EGR)system can effectively solve the problem of high NOx emissions when the engine is burning gasoline/diesel fuel.In addition,diesel engines do not require modifications to the diesel fueling system and other structures when burning gasoline/diesel blends.In this test,0~#diesel and 92~#gasoline were selected as test fuels,and 92~#gasoline was blended with 0~#diesel by volume fractions of 0%,20%and 40%respectively to prepare gasoline/diesel blended fuel,labeled as D100,D80G20 and D60G40,respectively.This paper first studies the effect of gasoline blending ratio on the physicochemical properties of gasoline/diesel blended fuel,and conduct engine bench test of D100,D80G20 and D60G40three fuels based on a supercharged intercooled,in-line four-cylinder high-pressure common rail diesel engine equipped with EGR,and comparative study of the combustion and emission characteristics of the engine when three different fuels are used.The research results are as follows:(1)With the increase of the volume fraction of gasoline in gasoline/diesel blended fuel,the cetane number,density,kinematic viscosity,distillation range and freezing point of D80G20 and D60G40 gradually decrease,and the low calorific value gradually increases;(2)Under the same load and EGR rate,compared with D100,the D80G20 and D60G40retardation periods increase,and the peak combustion pressure,peak heat release rate and peak combustion temperature of the mixed fuel are higher than D100.Under the same speed and load,with the increase of EGR rate,the retardation period of the three fuels increases,and the peak combustion temperature gradually decreases.Under all operating conditions,the injection strategy of diesel engine is pilot injection plus main injection;(3)Under the same load and EGR rate,when the engine is fueled with three kinds of fuel,the CA10,CA50 and CA90 of D80G20 and D60G40 are earlier than D100,and D60G40 has the shortest burning duration.Under the same load and EGR rate,the combustion duration of the three fuels increases with the increase of the rotational speed.At the same speed and load,the EGR rate increases,and the rapid combustion period and afterburning period of the mixed fuel increase;(4)The rotational speed is 1800r/min and 2200r/min.Under the same load and EGR rate,compared with D100,the premixed combustion intensity of the mixed fuel is enhanced,the peak in-cylinder combustion temperature is increased,the NO_X emission is increased,and the soot emission is reduced.Under the same load,as the speed and EGR rate increase,NOx emissions decrease and soot emissions increase;(5)When the engine speed is 1800r/min and 2200r/min,the concentration and volume concentration of ultrafine particles of gasoline/diesel fuel blend are significantly lower than D100,and the volume fraction of gasoline is larger.The less the ultrafine particulate matter is discharged.Under the same working conditions,the quantity and volume concentration of ultrafine particles increase with the increase of EGR rate. |
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