Modeling and Experimental Study of Uncontrolled Regenerations in SiC Filters with Fuel Borne Catalyst

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.