Physics-Based Modeling of Selective Catalytic Reduction System and Corresponding Reduced Order Dynamics

This paper focuses on developing the physics-based model of the SCR system. Through the use of first principles, governing equations of the SCR physics-based model are achieved. The SCR system is modeled in a series of segments. The main reactions are ammonia adsorption, desorption, reduction, and ammonia oxidation. The resulting non-linear partial differential equations are discretized and linearized to obtain a state space model. The model is extended to a sufficiently large order to achieve accuracy. The developed model is analyzed and the system dynamics are studied, validated using simulation studies of a Urea-SCR system. In addition, reduced order dynamics of the SCR system are also analyzed in this paper.