Development of a mathematical model for the porous media approach in simulating flow through a selective catalytic reduction (SCR) facility

Abstract

A selective catalytic reduction (SCR) system converts nitrogen oxide to water and nitrogen through chemical reactions in the catalyst layer. The complex flow inside SCR facilities is often examined using computational fluid dynamics (CFD) simulations where the screen plate is modeled as porous media owing to its complex shape. This porous media model nominally utilizes the pressure loss across the screen plate. However, a-priori determination of the model is difficult if on-site pressure data are unavailable or additional laboratory experiments cannot be performed. We hereby describe the development of a method for the porous media approach based on mathematical modeling of the force balance on the screen. This allows us to utilize the porous media approach without having any pressure drop information. We conducted particle image velocimetry (PIV) experiments to first validate CFD simulations that fully resolved the screen plate. Subsequently, CFD results using the porous media approach with the newly developed mathematical model were compared to that of the fully resolved simulations, and the overall flow structure including the main recirculation zone was shown to be similar. Thus, using the newly developed mathematical model, the internal flow field in complex engineering systems such as an SCR facility can be rapidly obtained with less computational cost and reasonable accuracy.