Development Of EGR System Based On A China ? Diesel Engine

With the development of society,environmental pollution and energy shortage is becoming critical,which is the major problem that we are facing today.And NOx and PM emission control of diesel engine has become one of the key technical issues that to be solved since the diesel engine vehicle ownership is growing every year.EGR(Exhaust Gas Recycle)technology has been widely concerned as an important measure to reduce NO_X content in diesel engine emissions.This paper describes the development of EGR system of a china ? diesel engine.It mainly focuses on model selection,structure design,EGR rates calculation and experiment verification,EGR valve performance test and exhaust emission test.First,this paper describes EGR model selection and then structure design.According to the structural characteristic of the developing china ? diesel,suitable cooling type,pressure loop,single and double channel,EGR valve structure and EGR cooler type were chosen.Eventually,detailed layout design of engine and its EGR system was done.Second,the differences of EGR rates of each cylinder were calculated by using CFD simulation method.After primary EGR system layout design,thermal boundary condition was obtained by BOOST thermodynamics simulations to do CFD calculation by using FIRE.The results show that the differences of EGR rates of each cylinder could reach 65.69%,which has far exceeded the limit of 10%.After extended the pipe after the mixing point of fresh air and exhaust gas,which could ensure more mixing time,new CFD calculation results show that the maximum difference of EGR rates is reduced to 2.96%,which meets the demand.Third,essential performance tests were design after EGR system structure confirming,including electrical performance testing,functional testing,self-learning testing.Those tests ensure the key components' performance of EGR system.Meanwhile,EGR cooler test was also being done to verification its cooling performance.Finally,combined with DPF post-processing system to build the bench for the whole performance test,and the results of the corresponding analysis.The results show that the EGR rate deviation of each cylinder is within 3%,and the validity of the EGR structure optimization scheme is verified.The emission test results meet the national limit and the external characteristic is 200.2 g / kW·h.The results of this paper provide a reference for the development of EGR system for light vehicle diesel engine,which provides a good foundation for meeting the ? emission standard of light diesel engine.