The performance of Diesel Particulate Filters is evaluated by pressure drop and soot charge capacity during operation and is controlled by the properties of the porous wall material (permeability, pore distribution, max. soot charge) and the geometry (channel-shape,- length, wall thickness) of the filter structure [1]. The manufacturing of ceramic filter segments proceeds over an extrusion process and requires expensive design specific tools. An empirical optimization with trial and error cycles in the hardware is extremely costly: a “virtual” optimization process via simulation is more promising [2]. Aim of the presented model is to analyze the influence of filter structure and material parameters on flow and soot deposition. The model geometry consists of a 3D unit cell of a typical ceramic particulate filter. Physical mechanisms included are free (channels) and porous (wall) gas flow, convective mass flow (gas soot concentration) and mass deposition (soot concentration in porous wall, soot cake formation) of soot. A comparison of model predictions with experimental results proved the validity and the applicability of the model for virtual design purposes.
Optimization of DPF structures with a 3D-unit cell model