摘要
提出柴油机SCR系统尿素分解效率的理论计算方法。试验研究了柴油机SCR系统尿素分解效率、NOx转化效率以及NH3泄漏量的关系,分析了空速、氨氮比、SCR温度对三者的影响。结果表明,NOx的转化效率与尿素分解效率的变化趋势基本相同;在催化剂活性温度范围内,尿素水溶液最终分解出NH3的效率都在90%以上;随空速的增大,尿素分解效率先增大再减小;氨氮比为1时,NOx的转化效率较高,但是NH3的泄漏量超出限值;氨氮比对尿素分解效率几乎没有影响;排气温度上升时,尿素分解效率增大。空速和SCR温度是影响尿素分解效率的最大因素。提出的计算方法能够呈现尿素分解效率的变化趋势,为提高SCR系统工作效率提供了依据。
In order to perfect the work efficiency evaluation system of diesel SCR system and improve the work efficiency of SCR system,the theoretical urea decomposition efficiency calculation method of diesel engine SCR system was proposed. The urea decomposition efficiency,amount of leakage of NH3 and NOx conversion efficiency of SCR system for diesel engine were investigated on an engine test bench,the influence of space velocity,NH3/ NO ratio and SCR temperatures were analyzed. Experiment results showed that the changing trend of NOxconversion efficiency and urea decomposition efficiency was basically the same. In the catalyst activation temperature range,the urea decomposition efficiency was above 90%; with the increase of space velocity,the urea decomposition efficiency was increased first and then decreased. NH3/ NO ratio was 1 with high NOxconversion efficiency,but the amount of leakage of NH3 was exceeded the limit value. NH3/ NO ratio had little effect on the urea decomposition efficiency,and it was increased with the amount of leakage of NH3 increasing. When the exhaust gas temperature was raised,the urea decomposition efficiency increased. The space velocity and exhaust gas temperature were the most important factors influencing the urea decomposition efficiency, the level of urea decomposition efficiency was the comprehensive effect of both. Through the study on the factors affecting the decomposition efficiency of urea,to reduce the deposition of urea in the exhaust pipe and improve the removal efficiency of NOx. The proposed calculation method can exhibit a trend of urea decomposition efficiency and provide a basis for improving the work efficiency of SCR system.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第6期282-286,309,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家高技术研究发展计划(863计划)资助项目(2012AA111704)
国家自然科学基金资助项目(51306070)
关键词
柴油机
选择性催化还原
尿素
分解效率
影响因素
Diesel engine
Selective catalytic reduction
Urea
Decomposition efficiency
Influencing factors
作者简介
马军彦，博士生，主要从事柴油机排放控制研究，E—mail：junyanm@163．com
通讯作者：曲大为，讲师，博士，主要从事发动机电子控制研究，E-mail：eewang404@163．com
