Simulation Study On Regeneration Of Diesel Particulate Filter

With the increasingly strict diesel exhaust emission regulations, diesel particulate filter become one of the most effective measures to control diesel particulate emissions. At present, the particulate filter technology is very mature while the filter regeneration technology develops very slowly. If only used the traditional test methods to study the regeneration proceed, it will consume large amounts of manpower and material resources, and design cycle is longer, the effect is poorer. It certainly will request the researchers to looking for theoretical guidance method and establish the simulation model of regeneration, so greatly reduces testing work, improve the design efficiency.This paper designed a setup of diesel particulate post-processing device based on fuel -injection catalytic combustion regeneration; the regeneration test-bed was set up to research heating process of regeneration. The experiments prove that fuel-injection catalytic combustion regeneration can realize heating process effectively, and the exit temperature of DPF achieve above 500℃if injection quantity increase to 60mL/min. Using variable injection quantity control scheme will increase the heating time, but it can reduce secondary pollution caused by regeneration. The simulation model of fuel-injection catalytic combustion regeneration was established by numerical simulation software GT-Power. The simulation results and test results of DPF heating process have showed agreement. The regeneration process has been optimized from the injection rate and auxiliary air strategy. Heating time has been shortening by 37.9%, while the capacity for heating has being increased by 3.4%.The particles combustion 3D model of DPF regeneration was set up to analyze the temperature of filter and thickness of PM layer and their influence during regeneration process. The calculation results indicate that the PM combustion process can be divided into four stages including preheating period, slow burning period, nasty burning period and tail burning period; the particles at the back end burns faster than that at the front end; the particles at the axial center burn faster than that near the edge; the max temperature value appears at the back end center of filter. Particles burning process will produce larger intense of temperature gradient which may cause filter crack; The ash which produced by burning of particles will lower filter body filtering length and filtering area, thereby reducing filter filtration efficiency.The influential factors of regeneration had been analyzed based on establishing particulate combustion model of regeneration. Simulation results indicate that we should keep appropriate exhaust flow mass and oxygen concentration during regeneration; the particle deposition quantities should be small during regeneration process and the particle as well as flow velocity should distribute uniformly; we should increase the mesh density when doing 3D-numerical simulation works under allowed conditions; When diesel engine operation conditions are changing, the wall temperature of filter will emerge fluctuations which against the regeneration during particulate filter regeneration process.The work provides an important guidance to research on the heating and combustion of particles during DPF regeneration, and provides theoretical basis to the further study on regeneration process of DPF.