Numerical Investigation on the Progressive Evolution of Regeneration Pattern with Feed Temperature in a Wall-Flow-Catalyzed Diesel Particulate Filter

Abstract

A two-dimensional transient model for wall-flowcatalyzed diesel particulate filter (DPF) regeneration is applied to investigate the regeneration process of DPF. User-defined subroutines are coupled to the commercial computational fluid dynamics code ANSYS Fluent to implement soot oxidation kinetics. Numerical results reveal that filter regeneration can proceed in three modes depending on the feed temperature: uniform combustion mode (Pattern I), transition mode (Pattern II), and propagating front mode (Pattern III). Pattern I is characterized by a small temperature rise of 20−160 K and a long regeneration time of about 600−2400 s. In contrast, Pattern III is characterized by a high peak temperature greater than 1400 K and a short regeneration time smaller than 40 s. Pattern II is the transition (mixed) mode in which the filter is regenerated by a moving reaction front which cannot conquer the whole filter length. For Pattern III, the propagating front originates from the downstream (subpattern a) to the midstream (sub-pattern b) to the upstream (sub-pattern c) as the feed temperature is increased from 893 to 943 K. Sub-pattern c results in the maximum peak temperature under all investigated operation conditions, while not shortening the regeneration time compared to sub-pattern a and sub-pattern b. These findings help to attain more favorable schemes for the thermal management optimization in DPF regeneration.