A method of coupling a three dimensional flow field with an one dimensional chemical method was proposed to perform a full-scale simulation of a diesel engine selective catalytic reduction(SCR) system to study the effect of flow uniformity distribution on catalytic reduction reaction. Using the exhaust information measured by the engine bench test

a SCR three-dimensional flow field simulation was conducted to study the flow velocity changes at the front cross section of the SCR catalytic converter under different operating conditions

and then the effect of the operating parameters on NOx conversion efficiency and by-product N2O formation was investigated under various flow rate distributions in order to provide a guidance for optimizing the control strategy of the SCR system. Results show that the difference in flow rates between the various regions of the front end of the SCR catalytic converter is obvious under different operating conditions. When the flow rate uniformity coefficient is within the range of 0.6 to 0.8

NH3/NOx is 1.1 and NO2/NOx is between 0.0 and 0.5

the NOx conversion efficiency is the highest

while the formation of by-product N2O is the lowest.