FILTECH 2022, The Filtration Event

Cologne, Germany

08.-10.03.2022

N. Hafen, A. Dittler, M.J. Krause

Wall-flow particulate filters are used for particulate matter (PM) removal from exhaust gas in a variety of aftertreatment systems of combustion engines. Here, they signif- icantly reduce PM emissions. Inside these filters, the gas flow is forced through a porous wall between oppositely arranged inlet and outlet channels.

During this process, porous PM layers, which consist of both reactive and inert com- ponents, are formed inside the filter channels, resulting in an increase of the filter back pressure. This leads to the necessity of regenerating the filter by oxidizing the reactive components continuously or in reoccurring intervals and breaking up the con- tinuous PM layer into individual layer fractions. When reactive-inert particulate matter structures re-arrange during the regeneration process, remaining inert material can be observed in different deposition patterns, impacting operational filter performance. The objective of this work is a deeper understanding of wall flow filter operational behaviour beyond sole engine applications.

In this work the open source software OpenLB is used with the homogenized lattice Boltzmann method (HLBM). By accounting for simulations with surface resolved parti- cles, the forces acting on them can be evaluated and detailed investigations of particle or layer fraction detachment and rearrangement processes can be performed. As a result, the hydrodynamic forces acting on individual PM layer fractions are retrieved in detail and set into relationship with a simplified adhesion force model. In that way, the transient behaviour of the detachment process during the filter regeneration is simu- lated. Additionally, the permeability influence of substrate and PM layer fractions on detachment and transport inside a single channel is evaluated.