Simulation Of NOx Storage and Reduction Catalyst: Model Development And Application

To fulfill future emission standards for diesel engines, combined after-treatment systems consisting of different catalyst technologies and diesel particulate filters (DPF) are necessary. For designing and optimizing the resulting systems of considerable complexity, effective simulation models of different catalyst and DPF technologies have been developed and integrated into a common simulation environment called ExACT (Exhaust After-treatment Components Toolbox). This publication focuses on a model for the NO_x storage and reduction catalyst as a part of that simulation environment.

A heterogeneous, spatially one-dimensional (1D), physically and chemically based mathematical model of the catalytic monolith has been developed. A global reaction kinetic approach has been chosen to describe reaction conversions on the washcoat. Reaction kinetic parameters have been evaluated from a series of laboratory experiments. The model was validated with data from passenger car dynamometer test bench and heavy duty commercial vehicle engine test bench measurements. The results show the applicability of the model over this wide range in size and operating conditions, underlining the suitability of the chosen modeling approach to the requirements. Series of simulations have been carried out to study the effects of various operating conditions on the converter performance.