Simulation Study On The Performance Impact Of Diesel Engine Fueled With Biodiesel

With the energy shortage and environmental pollution becoming more and more serious,the research of alternative fuel more and more is valued people.Nations of the world has been attaching importance to the study and development of biodiesel because of its environmental performance,reproducibility and convenient usage.Compared with conventional diesel fuel,the biodiesel can significantly reduce emission of Soot,but simultaneously increase emission of NO_x,so measures should be taken to solve this problem.The auto engine always runs in instantaneous status,so it is very important for study on influences of biodiesel on diesel engine performance in instantaneous status.Taking a four cylinder turbocharged diesel engine as the research object,the diesel engine performance fueled with different blend ratios of biodiesel and 0~#diesel are studied.The parameters of the diesel engine was not changed.According to the characteristics that NO_x emission is higher than 0#diesel fuel,EGR technology is taken to reduce NO_x emission in this paper.Effect on charecterastics of different blend ratios mixed fuels with different EGR rates are studied on Soot and NO_x emission of diesel engine.Holding by this principle that Soot and NO_x emissions have no diffence with original machine,the optimum EGR rate for different blend ratios mixed fuels is determined.At last,the transient modle for diesel engine was established.Influences of biodiesel on diesel engine performance in instantaneous status was studied.Effect on charecterastics of 30%ratios mixed fuels with different EGR rates are studied on Soot and NO_x emission.Study show that:(1)The Soot emissions and torque of diesel engine are reduced whereas that the NO_x emissions and BFSC are increased.The bigger the volume fraction of biodiesel,the greater the effect.(2)The exhaust emissions of diesel engine fueled with some blend ratios of biodiesel and 0#diese can have no significant change by adjusting the EGR rate at middle negative load.(3)The Soot emissions of diesel engine fueled with different blend ratios of bio-diesel and 0~#diesel are quite low at low negative load.The optimum EGR rate for different blend ratios mixed fuels can be determined according to the principle that the NO_x emissions have no significant change with original machine.(4)The Soot emission of diesel engine under constant speed and increasing torque transient operating condition is higher than steady condition.(5)The reducing effect and adding effect of biodiesel to diesel engine under constant speed and increasing torque transient operating condition is not obvious as steady condition.(6)The Soot and NO_x emissions of mixed fuels with 30 percent biodiesel can have no significant change by adjusting the EGR rate under constant speed and increasing torque transient operating condition.