Modeling of Urea Decomposition in Selective Catalytic Reduction (SCR) for Systems of Diesel Exhaust Gases Aftertreatment by Finite Volume Method

This study presents modeling of selective catalytic reduction (SCR) for systems of diesel exhaust gases aftertreatment. The main purpose of this work is to develop the modeling approach that allows accurate prediction of urea–water solution behavior (UWS) in the real diesel exhausts in temperature range 373 K to 873 K. The UWS is a key element of catalytic reduction of diesel NOx which utilizes ammonia as reducing specie. The finite volume method (FVM) extended by the nonrandom two liquids (NRTL) phase equilibrium model was used to perform the calculations. The results obtained were verified with experimental measurements. The comparison show that the NRTL extension introduced in this work allows reproducing the actual process conditions in the diesel exhaust environment. The accuracy of the results permits the model to be used for the design purposes and simulation approaches as well.