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Wall-flow Diesel particulate filters operating at low filtration velocities usually exhibit a linear dependence between the filter pressure drop and the flow rate, conveniently described by a generalized Darcy's law. It is advantageous to minimize filter pressure drop by sizing filters to operate within this linear range. However in practice, since there often exist serious constraints on the available vehicle underfloor space, a vehicle manufacturer is forced to choose an “undersized” filter resulting in high filtration velocities through the filter walls. Since secondary inertial contributions to the pressure drop become significant, Darcy's law can no longer accurately describe the filter pressure drop. In this paper, a systematic investigation of these secondary inertial flow effects is presented.

Diesel particulate trap regeneration is a complex process involving the interaction of phenomena at several scales. A hierarchy of models for the relevant physicochemical processes at the different scales of the problem (porous wall, filter channel, entire trap) is employed to obtain a rigorous description of the process in a multidimensional context. The final model structure is validated against experiments, resulting in a powerful tool for the computer-aided study of the regeneration behavior. In the present work we employ this tool to address the effect of various spatial non-uniformities on the regeneration characteristics of diesel particulate traps. Non-uniformities may include radial variations of flow, temperature and particulate concentration at the filter inlet, as well as variations of particulate loading. In addition, we study the influence of the distribution of catalytic activity along the filter wall.

As demand for wall-flow Diesel Particulate Filters (DPF) increases, accurate predictions of DPF behavior, and in particular their pressure drop, under a wide range of operating conditions bears significant engineering applications. In this work, validation of a model and development of a simulator for predicting the pressure drop of clean and particulate-loaded DPFs are presented. The model, based on a previously developed theory, has been validated extensively in this work. The validation range includes utilizing a large matrix of wall-flow filters varying in their size, cell density and wall thickness, each positioned downstream of light or heavy duty Diesel engines; it also covers a wide range of engine operating conditions such as engine load, flow rate, flow temperature and filter soot loading conditions. The validated model was then incorporated into a DPF pressure drop simulator.