Ammonia storage and slip under steady and transient state in close-coupled SCR  

作　　者：Shiyu Liu Zhaohuan Zhang Zexian Guo Boyuan Wang Buyu Wang Xiao Ma Shijin Shuai 

机构地区：[1]State Key Laboratory of Automotive Safety and Energy,Tsinghua University,Beijing 100084,China [2]Institute for Aero Engine,Tsinghua University,Beijing 100084,China

出　　处：《Journal of Environmental Sciences》2024年第4期470-481,共12页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.51976100);the co-founding of FAW Jiefang Automobile Co.,Ltd.Wuxi Diesel Engine Factory,Saudi Aramco Technologies Company;Shandong Chambroad Petrochemicals Co.,Ltd.with the project“Fuel and Engine Co-optimization for high Efficiency and Net-Zero Emission Heavy-duty Engine”。

摘　　要：The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold start.This paper investigated the optimal ammonia storage under steady and transient state in the cc-SCR.The study showed that a trade-off between NOx conversion efficiency and ammonia slip is observed on the pareto solutions under steady state,and the optimal ammonia storage is calculated with ammonia slip less than 10μL/L based on the ChinaⅥemission legislation.The rapid temperature increase will lead to severe ammonia slip in the transient test cycle.A simplified 0-D calculation method on ammonia slip under transient state is proposed based on kinetic model of ammonia adsorption and desorption.In addition,the effect of ammonia storage,catalyst temperature and temperature increasing rate on ammonia slip are analyzed.The optimal ammonia storage is calculated with maximum ammonia slip less than 100μL/L according to the oxidation efficiency of ammonia slip catalyst(ASC)downstream cc-SCR.It was found that the optimal ammonia storage under transient state is much lower than that under steady state in cc-SCR at lower temperature,and a phase diagram is established to analyze the influence of temperature and temperature increasing rate on optimal ammonia storage.

关 键 词：Close-coupled SCR Ammonia storage and slip Steady and transient state Generic algorithm 

分 类 号：X701[环境科学与工程—环境工程]