Simulation on soot deposition and combustion in diesel particulate filter

We have simulated the flow in a real cordierite DPF using the lattice Boltzmann method. Inner structure of the filter is analyzed by a 3D X-ray CT technique. Two processes of soot deposition for PM trap and soot combustion for filter regeneration process are considered. Especially, the effect of NO₂ on the soot oxidation is examined, which is recently proposed as on-board regeneration system. The reaction rate has been determined based on previous experimental data. The estimated values of Arrhenius factor and activation energy are A = 146 1/s, E = 79.5 kJ/mol with NO₂, and A = 1.20 1/s, E = 64.9 kJ/mol without NO₂. Results show that, the flow field and pressure change inside the filter are clearly visualized. The pressure distribution depends on the non-uniformity of pore structure. The flow is largely changed with soot deposition, with higher pressure drop across the filter (filter back-pressure). The obtained correlation between total accumulated soot and the filter back-pressure is well in accordance with reported experimental results. In combustion simulation, the effect of NO₂ addition to promote the soot oxidation is confirmed. These are useful information to develop the future regenerating DPF system.