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Compliance with future emission standards for diesel powered vehicles is likely to require the deployment of emission control devices, such as particulate filters and DeNOx converters. Diesel emission control is merging with powertrain management and requires deep knowledge of emission control component behavior to perform effective system level integration and optimization. The present paper focuses on challenges associated with a critical component of diesel emission control systems, namely the diesel particulate filter (DPF), and provides a fundamental description of the transient filtration/loading, catalytic/NO2-assisted regeneration and ash-induced aging behavior of DPF's.

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.