Modeling and Experimental Study of Uncontrolled Regenerations in SiC Filters with Fuel Borne Catalyst 2004-01-0697

The objective of this paper is to study the parameters affecting the evolution of “uncontrolled” regeneration in diesel particulate filters with fuel-borne catalyst (FBC) support with emphasis on the development of thermal stresses critical for filter durability. The study is based on experiments performed on engine dynamometer, corresponding to “worst-case” scenario, as well as on advanced, multi-dimensional mathematical modeling. A new 2-dimensional mathematical model is presented which introduces an additional dimension across the soot layer and wall. With this dimension it is possible to take into account the variability of catalyst/soot ratio in the layer and to compute intra-layer composition gradients. The latter are important since they induce interesting O₂ diffusion phenomena, which affect the regeneration evolution. The capability of the model to predict the temperature distribution in the filter is validated based on a series of engine tests with and without post-injection. Special emphasis is given on the effect of catalyst/soot ratio in the soot layer. Dedicated testing for the characterization of emitted nano-particles using particle size measurements are employed to identify the conditions under which the FBC can be emitted as “free” (not agglomerated with soot) particle.