Effects Of Different EGR Rates On Performance Of Hydrogen Fueled Engines At Low And Medium Speeds

The world today is facing two serious problems of fossil energy shortage and environmental pollution.The development of clean and pollution-free alternative energy has become an inevitable trend.Hydrogen has been favored by scientists from all over the world for its low ignition energy,wide range of ignition limits,fast flame propagation speed,clean and renewable,etc.As a substitute fuel for vehicles,hydrogen has broad development prospects.NO_x is the only harmful emission of hydrogen-fueled engines at high temperatures.EGR(Exhaust Gas Recirculation)technology is used to re-introduce part of the residual exhaust gas into the intake pipe,thereby improving the pressure of the intake pipe and the charging efficiency of the cylinder.Effective measures for performance.In recent years,with the country's increasingly strict requirements on emissions regulations.Exhaust gas recirculation systems have become an integral part of modern automotive engines.In this paper,a combination of theoretical analysis and numerical simulation is used.A modified Jialing JH600 hydrogen engine is used as a prototype.The threedimensional simulation software SolidWorks is used to establish a three-dimensional model of the hydrogen fueled engine.The simulation calculation is based on the AVLFIRE software.Firstly,the effects of EGR rate on the intake composition,intake state,turbulent kinetic energy and mixture uniformity of the hydrogen engine under different operating conditions were analyzed.The EGR rate on the combustion characteristics and emissions of the hydrogen engine under different operating conditions was analyzed.characteristic.Based on the comprehensive evaluation of power,economy and emissions,the optimal EGR ratio in each working condition was determined through linear weighted optimization analysis.The research results show that the addition of EGR will have a certain blocking effect on the intake process.The difference in the effect of different EGR rates on the intake block is not obvious.As the EGR rate increases,the actual fuel-air equivalent ratio in the cylinder will increase.The combustion state parameters such as temperature,pressure,and instantaneous heat release rate in the cylinder will decrease in different amplitudes.The effect of EGR rate to reduce NO_x emissions is very obvious.Adding a small amount of EGR rate at low and medium speed conditions can greatly reduce NO.In order to find the optimal EGR rate,this paper uses linear weighting to comprehensively measure the dynamic economy and emissions on the basis of the low and medium speeds.The optimal value of the EGR rate is 0% at low and medium loads.The optimum value of EGR rate is 5% under medium load and medium and high load conditions.