Influence and optimization of urea injection parameters on SCR characteristics based on response surface methodology

Abstract

As global environmental regulations continue to tighten, the reduction of vehicle exhaust emissions has become a priority for automakers and environmental agencies. The selective catalytic reduction (SCR) system is recognized as one of the most effective technologies for reducing nitrogen oxide (NO_x) emissions from diesel engines. In this study, the effects of various urea injection parameters (including particle size, injection speed, and solution concentration) on SCR system performance were analyzed using a numerical simulation model. Firstly, a single-factor analysis was performed to examine how different injection parameters affect NO_x conversion (de-NO_x) efficiency, NH₃ uniformity, wall film temperature, and wall film mass. Key factors and trends influencing SCR system performance were identified, and the optimal parameter range was determined. Secondly, response surface methodology (RSM) was employed for multivariate optimization analysis, enabling the development of a mathematical model linking parameters with response variables to identify the optimal combination for enhancing SCR performance. Finally, the effectiveness of response surface optimization was verified by comparing the predicted values with the actual simulation results. The findings revealed that the optimized de-NO_x efficiency increased by 5.33 %, NH₃ uniformity improved by 0.041, wall film temperature rose by 10.6℃, and wall film mass decreased by 0.051 g. This study not only provides a solid theoretical foundation for the design of urea injection systems but also offers valuable insights for optimizing SCR systems in practical applications.