Investigation on the effects of non-uniform porosity catalyst on SCR characteristic based on the field synergy analysis

Selective catalytic reduction catalyst was commonly used in the denitrification of exhaust from the internal combustion engine. In the paper, a three-dimensional mathematical model was developed and employed to study the flow and heat transfer in the non-uniform selective catalytic reduction catalyst system. The denitrification reaction of selective catalytic reduction catalyst was employed to predict the NOx conversion efficiency. In addition, the field synergy principle is employed to analyze the effects of velocity and temperature fields on the heat transfer process. The results show that the non-uniform porosity catalyst can effectively reduce the catalyst back pressure. At 100 g/s, the pressure drop in the non-uniform porosity catalyst was 0.91 kPa lower than the high porosity catalyst. The total heat transfer rate of the non-uniform porosity catalyst was on average 1.1% lower than the uniform porosity catalyst. The low heat transfer rate ensures that the temperature drop is reduced. Thus, the denitrification reaction is improved by the high temperature. In addition, the field synergy number of non-uniform porosity catalysts is on average 0.53% lower than uniform porosity catalysts, which indicates energy transfer from the diameter change region to the outside is reduced. This proves the non-uniform porosity structure is more favorable for the denitrification reaction.