Experimental Study Of Diesel Engine CDPF Simulation And Application Of Integrated Aftertreatment System

Under the background of China?emission standard,to further reduce diesel particulate emissions,this paper focuses on the Catalyzed Diesel Particle Filter(CDPF)and its integrated aftertreatment system,based on the engine bench and vehicle emission test,combined with experiment,simulation,and design of experiment,the related research work is carried out.A DPF simulation model was established,and the capture and regeneration process was simulated.The results showed that soot was easily captured at both ends of the carrier,showing a"concave"distribution.DPF front end soot is regenerated first,and the temperature at the center and back end of the carrier was higher during the regeneration process.The effects of different wall thicknesses and wall permeability(k_wall)on the pressure drop of asymmetric channels were investigated.The results show that the asymmetric structure can effectively reduce the pressure drop when the soot is loaded.The thicker the wall,the smaller the wall permeability,the larger the pressure drop and the larger the carbon load,and the more significant the influence on the pressure drop is.The influence of ash on the pressure drop of DPF was simulated and analyzed,and the ash distribution evaluation function?was constructed.It was found that the influence of ash distribution coefficient(s)on pressure drop was determined by ash and wall property parameters.When the permeability of ash cake layer(k_ash)>k_wall,?>0,that is,the pressure drop of ash distribution in filter cake layer is small,k_ash<k_wall,?<0,the pressure drop of ash distribution in plug type is small.There is a k_ash,and?value approaches to a critical value at a certain k_wall,at which time s has little influence on pressure drop.The larger the carbon load,the larger the diameter ratio of inlet and outlet channels(d₁/d₂)is,and the larger the?is.When k_ash is 1×10^-12 m²,the larger the ash component is,the larger the?is,when k_ash is 1×10^-14 m²,the larger the ash component is,the smaller the?is.The smaller d₁/d₂,the larger the ash distribution coefficient and ash component,and the greater the pressure drop during DPF regeneration.Based on the bench test,CDPF coating and soot loading pressure drop characteristics test,DOC+CDPF cylinder after injection and DTI condition regeneration test,WHTC emission test of China?integrated aftertreatment system were carried out.The results show that the coating has a certain influence on diesel engine performance.According to the Map of pressure drop,the higher the carbon load,the greater the pressure drop.The WHTC cycle regeneration interval mileage estimation model was established.Based on the cycle emission test data,the CDPF cycle regeneration interval mileage met the development requirements of 5000 km,and the integrated aftertreatment system met the national China?emission standard.In the vehicle C-WTVC cycle emission test,the DOC+CDPF aftertreatment system can effectively reduce CO,THC,and PM emissions,but has little impact on NOx emissions.The comprehensive emission reduction rate of gaseous pollutants in the whole cycle is 51.20%,and the comprehensive emission reduction rate of PM is 96.69%.The onboard emission test results show that the capture efficiency of the DOC+CDPF scheme is higher than that of the CDPF scheme.Because of the above in-use vehicle modification tests,the author gives specific treatment suggestions.After a long period of work in DPF,there is inevitably residual ash in the channel.To reduce its influence on pressure drop,orthogonal and response surface methods were adopted to conduct sensitivity analysis of pressure drop with three factors and three levels and to optimize the design of CDPF.Based on the analysis results,the influence on pressure drop is weak when the k_ash value is large,and the influence degree of each parameter on pressure drop is the wall thickness>d₁/d₂>k_ash.When the DPF is optimized,it is suggested to give priority to the factors that have a great influence on the pressure drop and to use the lubricating oil containing Mg-based cleaning agent to reduce the pressure drop.