Partial Regenerations in Diesel Particulate Filters

In real-world driving, the exhaust gas conditions in the particulate filter may induce incomplete filter regenerations. The implications of such partial regenerations are examined in this paper in terms of pressure drop and filter thermal loading. The methodology followed is based on a 2-D simulation model of the regeneration process. The model is initially fine-tuned and validated based on experimental results from engine bench testing. The validated model is subsequently employed to simulate a series of regenerations starting from different possible initial soot distribution patterns. The results are evaluated based on the calculated maximum thermal gradient in the filter that would produce the critical thermal stress for filter structural integrity. It is shown that the filter thermal loading can be significantly higher in case of initially non-uniform soot distribution. Therefore, the design of durable filters and efficient regeneration systems should not only be based on a maximum allowable soot loading (as used in many previous studies), but also take into account the additional risk of “unexpected” thermal stress resulting from non-uniformly distributed soot.