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This paper focuses on some of the DPF system design issues where 3-dimensional modeling is necessary. The study is based on an existing 3-dimensional DPF model (axitrap) which is coupled to a commercial CFD code (Star-CD, CD-Adapco). The main focus is the effect of the inlet pipe geometry on soot distribution in the filter during loading and regeneration mode. The results show that due to the self-balancing effect, the resulting soot distribution in the filter under typical loading modes with low flow rates is quite uniform. With the assumption of adiabatic inlet pipe, the effect of non-symmetric inlet pipe is also negligible even during regeneration. However, under the realistic assumption of a non-adiabatic inlet pipe, the effect of inlet pipe geometry becomes very significant. Especially, for the case of a bent-shaped inlet pipe, the risk of impartial regeneration of the filter increases significantly.

The objective of this study is to present a particulate filter concept, based on a new porous material: INCOFOAM® HighTemp, a Ni-based superalloy foam. The paper examines the filtration and pressure drop characteristics as well as the regeneration performance of different filter configurations, based on experimental data and modeling. A number of different foam structures with variable pore characteristics are studied. The experimental testing covers flow and pressure drop behavior with air and exhaust gas, filtration efficiency measurements as function of particle size and regeneration rate measurements. The testing starts from mini-scale reactors and proceeds to real exhaust testing on the engine bench as well as vehicle tests on the chassis dynamometer and on-road. In parallel, a previously developed mathematical model is applied to study and understand the filtration and pressure drop mechanisms in the case of clean and soot loaded filters.

In order to use modeling as a predictive tool for real-world particulate filter designs (segmented filters, non-axisymmetric designs), it is necessary to develop reliable 3-dimensional models. This paper presents a 3 d modeling approach, which is validated against engine-bench measurements with both FBC and CDPF systems. Special emphasis is given to the prediction of the transient inlet flow distribution, which is realized without resorting to external CFD software. The experimental and modeling results illustrate the 3-d nature of the problem, induced by the heat capacity and conductivity effects of the cement layers. It is possible to predict the localization of regeneration in certain areas of the filter (partial regeneration), as a result of poor heat transfer to thermally isolated regions in the filter. The accuracy of the model was validated by extensive comparisons with temperature measurements in 30 positions inside the filters and at various operating conditions.