Numerical simulation of continuously regenerating diesel particulate filter

In many countries, stricter exhaust emission standards are being set, and a diesel particulate filter (DPF) has been used to trap particulate matters (PM) including soot in diesel exhaust gas. It is reported that DPF filling with PM causes higher back-pressure and more fuel consumption, and continuously regenerating DPF is needed. Usually, to reduce the soot oxidation temperature, a catalyzed DPF is used. However, the phenomena inside DPF are not well understood, because it is difficult to conduct measurements inside the filter. In this study, we simulated soot oxidation and deposition by the lattice Boltzmann method to observe the transport process in continuously regenerating DPF. The inner structure of the filter was obtained by an X-ray CT technique. The reaction rate of soot oxidation by the Pt catalyst, as well as soot deposition probability in the numerical model, was evaluated in experiments. The soot trap and oxidation were investigated to discuss the conditions for the continuous regeneration. When the filter temperature (T-w) is 600 K, the amount of deposited soot is quite similar to that without considering the soot oxidation, so that the soot is not oxidized at this temperature. When T-w is raised to be 800 K, the amount of deposited soot is saturated. Thus, at T-w = 800 K or higher, the filter clogging can be avoided to achieve the continuous regeneration. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.