Numerical Simulation Of Influencing Factors Of Active Regeneration Of Heavy-Duty Diesel Engine CDPF

The global diesel vehicle emission regulations are becoming stricter,For the heavy-duty diesel vehicle Euro VI emission regulations,compared with the Euro V emission regulations,the particulate matter(PM)emissions are reduced by 50%,and the particulate number(PN)is increased limits.The wall-flow diesel particulate filter(DPF)can effectively reduce the particulate matter emissions of diesel engines.It is also the only technical means to make PM emissions meet diesel emission regulations.DPF mainly reduces the PM emissions of diesel engines through physical filtration.However,as the PM accumulates in the DPF tunnel for a long time,the pressure drop of the DPF gradually increases,which leads to an increase in the exhaust back pressure of the engine,which reduces the economy and power of the diesel engine.Therefore,in the use of the DPF,it is generally required to remove the PM accumulated in the DPF by means of an external heating source to complete the active regeneration of the DPF.Different influencing factors(carbon loading,inlet temperature,space velocity)during active regeneration will have different effects on the DPF regeneration process.Inappropriate regeneration conditions may damage the DPF and even induce fire.In this study,the numerical simulation method is used to simulate the different influencing factors of the DPF active regeneration process to determine the safe boundary conditions of active regeneration,and provide theoretical basis for the experiment.The effects of carbon loading,inlet temperature and space velocity on the maximum temperature and maximum temperature gradient during active regeneration of DPF were analyzed by numerical simulation.The study found that the higher the initial carbon loading and inlet temperature of DPF,the higher the maximum temperature and maximum temperature gradient of the carrier during the active regeneration process.With the linear increase of the inlet temperature,the maximum temperature shows an exponential increase.The higher the space velocity,the lower the maximum temperature and maximum temperature gradient of the carrier during the active regeneration process.Through numerical simulation,the worst case of DPF active regeneration,Drop To Idle(DTI),was studied.The effects of DTI entry time,carbon loading,inlet temperature and space velocity during DPF active regeneration on the maximum temperature and maximum temperature gradient during active regeneration of DPF are studied.The study found that when the target temperature set by CDPF active regeneration is reached,the earlier the entry time is,the higher the maximum temperature is,and the time point at which it appears first decreases and then increases.At the same time,the maximum temperature gradient is also larger,and the time point at which it appears is higher;The higher the inlet temperature and carbon load,the higher the maximum temperature and the larger the maximum temperature gradient;the higher the space velocity,the smaller the maximum temperature and maximum temperature gradient.Through the study of the active regeneration process in two different situations,it is found that the influence of inlet temperature on CDPF is more prominent than that of other influencing factors during normal active regeneration.When performing DTI simulation,the influence of the time point of entering DTI on CDPF is more prominent.Regardless of the influencing factors,during the DPF regeneration process,due to heat conduction,the temperature gradient distribution appears to gradually increase from the axis of the DPF to the edge of the carrier;the temperature distribution appears from the edge of the inlet end The tendency of the central axis of the outlet end to gradually increase.