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In 2007 emissions regulations for on-road light to heavy duty Diesel trucks will require the use of Diesel Particulate Filters (DPFs). The uniform distribution of soot on the DPF is critical for adequate long term performance of these DPFs. This is especially true when cordierite is used instead of silicon carbide for the DPF substrate, due to the reduced thermal conductivity and reduced peak temperature capability of cordierite. In addition to flow uniformity, an inverted flow pattern where more of the flow is forced radially outward on the substrate face could be beneficial to counteract thermal losses in the converter. This paper describes a dispersion device that can improve flow geometry with a low backpressure penalty. Computational fluid dynamics (CFD) results and experimental data are presented for this device. Additionally, cone design options are explored, and CFD analysis results of the cone design are presented.

A numerical study of transient, compressible, reacting flow inside an adiabatic catalytic converter is carried out with the one–dimensional model. The important physical/chemical phenomena existing in the catalyzed monolith are included in the model. The effects of the time dependent inlet mass flow rate and some important geometrical parameters on the gas/solid phase temperatures along the converter and the conversion efficiency are investigated. Results show that the monolith (wall) temperature along the converter, the maximum monolith temperature, the location of the reaction front, and the conversion efficiency are affected by time dependent fluctuations of the inlet mass flow rate. In addition, the converter characteristics and the conversion efficiency are very sensitive to the geometrical parameters (such as the cell density, the void fraction, and the wall thickness).

The Objective of this paper is to explain a procedure for using Arbitrary Shape Deformation (ASD) technology coupled with Computational Fluid Dynamics (CFD) software for product development of a generic catalytic converter inlet-cone diffuser. The paper uses the development of an inlet-cone diffuser as an example of such a process. The non-uniformities of the flow field at the inlet of the catalytic converter bricks are considered to have a negative impact on the converter performance. Computational Fluid Dynamics (CFD) is a powerful tool for computing the flow field in the exhaust system and the catalytic converter which enables the engineers to optimize the geometry of the inlet cone at a very early design stage. The goal of this study is to optimize the shape of an inlet-cone diffuser upstream of a catalytic converter to reduce the pressure drop and maximize the uniformity of exhaust gas distribution on the catalytic converter inlet.