为了厘清复杂工况下影响柴油机氨选择性催化还原（NH₃-SCR）系统脱硝的关键因素，以指导SCR系统开发及运行，基于某柴油机在世界统一瞬态循环（WHTC）工况下的台架试验数据，构建了GT-Power模型并进行了验证，通过耦合气体动力学和化学反应机理，分析SCR脱硝过程的规律和关键影响因素。仿真结果表明：冷起动工况下NH₃-SCR系统的NO_x还原效率随排气温度的升高而明显提高，温度高于210 ℃后反应逐渐趋于稳定，600 s后平均还原效率高达99.88%；热起动工况下NO_x还原反应迅速开启，600 s后平均还原效率为99.54%；此外，尿素喷射量对NO_x还原有较大影响，当尿素喷射量过多造成过剩，会导致氨逃逸。

The denitrification process of NH₃-SCR system of diesel engine was studied to clarify key factors affecting denitrification of diesel engines under complex operating conditions and to guide SCR development and operation. Based on the data of a diesel engine operating under world harmonized transient cycle (WHTC), GT-Power model was built and verified. Then the rules and key influencing factors of SCR denitrification process were explored through the simulation that coupled gas dynamics and chemical reaction mechanism. The results show that the NO_x reduction efficiency of NH₃-SCR system under cold start conditions obviously increases with the increase of exhaust temperature, the reaction gradually stabilizes when the temperature is higher than 210 ℃, and the average reduction efficiency is 99.88% after 600 s. In contrast, the NO_x reduction reaction starts quickly under hot start condition and the average reduction efficiency is 99.54% after 600 s. In addition, the urea injection amount has a greater impact on NO_x reduction, and too much urea injection will result in ammonia residual and hence ammonia escape.