Aspects of multifunctional diesel particulate filters and their efficient simulation

Abstract

Following the successful market introduction of diesel particulate filters (DPFs), this class of emission control devices is expanding to include functionalities, in addition to particle filtration, such as gas species oxidation and reduction to the extent that we should today refer to them as Multifunctional Reactor Separators. This trend poses many challenges for the modeling of such systems. In the present paper we address mathematical descriptions of some specific aspects of multifunctional DPFs for inclusion in comprehensive simulation tools in a physically accurate and computationally efficient manner. In particular, we study the behavior of thin, coating layers on top of the filter wall, and their effect on particle collection efficiency and pressure drop with the aid of Digital Material techniques that provided a guidance for the development of coated DPFs with added particle collection efficiency and lower pressure drop during soot loading. Soot–catalyst contact dynamics during soot oxidation by catalytic coatings was investigated with the application of a model including the distribution of different soot–catalyst contact states which is shown to be in very good agreement with the experimental data. Finally an analytical framework has been developed to describe the reactions of exhaust gas species in a DPF wall endowed both with a gas oxidation function and a reducing function (based on NH3-Selective Catalytic Reduction). The developments can be readily incorporated in DPF simulation tools, and enable the efficient and accurate simulation of multifunctional DPFs.