Simulation of Transient Operation for NH3-SCR&nbsp;Denitrification System of Diesel Engine

Vehicle Engine ›› 2025, Vol. 0 ›› Issue (4) : 15-22.

Simulation of Transient Operation for NH₃-SCR Denitrification System of Diesel Engine

CHEN Zetao^1,2,NING Wenfei¹,CHEN Zejia¹,ZHANG Shoujun¹,TAN Shuhuang¹,DENG Banglin¹

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Abstract

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.

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diesel engine / selective catalytic reduction / nitrogen oxides / transient condition

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CHEN Zetao, NING Wenfei, CHEN Zejia, ZHANG Shoujun, TAN Shuhuang, DENG Banglin. Simulation of Transient Operation for NH₃-SCR Denitrification System of Diesel Engine[J]. Vehicle Engine. 2025, 0(4): 15-22