Numerical Study on the Effect of Geometric Shape of DOC/DPF and Catalyst Loading for NO ₂ -assisted Continuous Regeneration

In recent years, several methods to regenerate PM (Particulate Material) from DPF (Diesel Particulate Filter) have been developed to meet getting more stringent emission regulations. A favorable technology is NO₂ -assisted regeneration method due to the capability of continuous regeneration of PM under much lower temperature than that of thermal regeneration. The minimization of maximum DPF wall temperature and the fast Light-off during regeneration are the targets for the high durability of the DPF system and the high efficiency of regeneration. In this study, one-channel numerical modeling has been adopted in order to predict a thermal behavior of the monolith during regeneration and a conversion rate of NO₂ from NO with a combined exhaust system of DOC (Diesel Oxidation Catalyst) and DPF. The simulation results are compared with experimental data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading and the volume ratio between DOC and DPF on the conversion and regeneration efficiency have been numerically investigated. The results indicate that the model of ‘volume ratio of DOC/DPF=1.5’ with a same diameter of both monoliths showed almost the maximum performance on the conversion and regeneration efficiency. About 55 g_Pt / ft³_monolith of catalyst (Pt) loading under the engine operating condition in this study is enough to maximize the conversion and regeneration efficiency.