Effect Of Fuel Injection Strategy Coupling EGR On Performance Of Biodiesel/Diesel/PODE_3-4 Hybrid Fuel Diesel Engine

In the context of the shortage of fossil energy and environmental pollution caused by energy consumption,the search for renewable environmentally friendly alternative fuels has become a hotspot in the research of internal combustion engines.Under the increasingly stringent emission regulations,the fuel injection system is gradually electronically controlled,and the fuel injection parameters can be flexibly adjusted according to changes in engine operating conditions.Systematic research on the impact of diesel engine fuel injection strategy on performance is of great significance for the application of alternative fuels and the optimization of control strategies.In this paper,a four-cylinder 2.17L displacement,turbocharged diesel engine is used to achieve low temperature combustion by introducing 20%EGR,and the effect of fuel injection strategy on the performance of biodiesel/diesel/PODE_3-4 hybrid fuel diesel engine is studied.The fuel used in the test was D100（pure diesel）,BD20（20%rapeseed biodiesel was blended in pure diesel by volume）,BDP10(10%PODE_3-4 was blended in BD20 by volume)and BDP20(20%PODE_3-4 was blended in BD20 by volume).Diesel engine combustion and emissions data were measured by changing parameters such as single injection injection timing,injection pressure and pilot-injection strategy（pilot-injection and pilot-injection timing）.The results of single injection test show that when the injection timing is the same,the Maximum Pressure Rise Rate（MPRR）of the four fuels range as D100>BD20>BDP10>BDP20;the fuel consumption of pure diesel is lower than the other three Mixed fuel;delayed injection timing,reduced NOx emissions from all fuels,increased HC emissions,and decreased Soot and CO emissions.Compared with D100,BD20 has higher soot and HC emission,and the total particulate matter concentration and mass concentration increase.However,after adding PODE_3-4,Soot and HC emissions decrease,total particulate matter concentration and mass concentration decrease,and with the increase in the proportion of PODE_3-4 blending,the trend is more pronounced.The fuel injection pressure test results show that:the fuel injection pressure is increased,the peak pressure and heat release rate of all fuels increased,the ignition delay shortened,the exothermic starting point advanced,and the MPRR increased;the fuel consumption rate of the four fuels range as:D100<BD20<BDP10<BDP20;increasing fuel injection pressure,Soot,HC and CO emissions of four fuels are reduced,but NOx emissions are increased;compared to D100,Soot emissions of BD20 are increased.Mixed PODE_3-4 can significantly reduce Soot emissions,in which BDP20 almost achieves zero discharge of Soot;increase injection pressure,total particle number concentration and mass concentration of all fuels are reduced;when injection pressure is the same,total of four fuels The mass concentration of the particulate matter range as:D100>BD20>BDP10>BDP20.The results of the pilot-injection strategy test show that:the pre-injection amount is increased,the pilot-injection heat release peak is increased,the main injection heat release rate is lowered,the combustion is advanced and the average cylinder pressure is increased;in order to achieve the simultaneous reduction of NOx and Soot emissions,reduce the amount of pilot-injection at a smaller pilot-main interval.Compared with D100,the Soot and HC emissions of BD20 increased,and the emissions of NOx,Soot,CO,HC,etc.of BDP10 and BDP20 decreased.The effect of pilot rate on diesel particulate matter emission is more obvious than that of pilot-main interval,and the pilot-injection amount is increased.The total particulate matter concentration and mass concentration of the four fuels are simultaneously reduced.In addition,the fuel properties have a significant impact on the particulate matter emissions of diesel engines.Compared with D100,the total particulate matter concentration,mass concentration and geometric mean particle size of BD20 increase,while the total particulate matter concentration,mass concentration and geometric mean particle size of BDP10 and BDP20 are both significantly reduced.