Internal pore diffusion and adsorption impact on the soot oxidation in wall-flow particulate filters

Abstract

The automotive industry is driven its efforts to cleaner internal combustion engines. As a result, the engine has become conditioned by the exhaust aftertreatment systems. The regeneration of wall-flow particulate filters (PFs) evidences such an interaction. The PFs prevent the soot emission whereas, as a counterpart, the fuel consumption increases. Consequently, passive and active regeneration strategies are needed to clean the filter back and limit the penalty in CO2. In this context, modelling tools play a key role to achieve a comprehensive understanding and control of the regeneration. In this work, a regeneration model coupled to a one-dimensional compressible unsteady flow solver for PFs is presented. The importance of the main physical and chemical steps related to the soot oxidation is discussed. The influence of the diffusion of gaseous reactants inside the primary soot particles is firstly addressed. The inclusion of this step into the definition of the reaction rate provides temperature dependence to the soot specific surface. Next, the reactants adsorption is analysed. This step leads to define a surface coverage, which behave as an equivalent reaction order. It allows figuring out the influence of the gaseous reactants concentration on the reaction rate and its dependence with the temperature.