摘要
为研究工作参数对双介质低温等离子体反应器性能的影响,建立了双介质阻挡放电型低温等离子体反应器试验系统,观察空气放电产生的 NO、NO2体积分数随放电频率、放电电压峰-峰值及空气流量等因素的变化.结果表明：不同放电频率时,双介质低温等离子体反应器气体放电反应机理不同;放电频率为7 kHz时,NO、NO2均随放电电压峰-峰值线性增长;放电频率为8 kHz时,随着放电电压峰-峰值的增大,NO先不变后增长,NO2线性增长;放电频率为9 kHz时,随着放电电压峰-峰值的增大,NO始终维持在较低水平,NO2先不变后增长;NO、NO2体积分数随空气流量的增大而减小,不同空气流量时,NOx总体变化规律不会改变;双介质低温等离子体反应器放电频率为9 kHz,放电电压峰-峰值为9~23 kV时,可产生较多的活性物质,同时避免大量副产物的生成.该研究可为利用NTP技术降低柴油机排放污染物提供参考.
The working principal of selective catalytic reduction （SCR） system is that urea solution, whose mass fraction is 32.5%, is injected into exhaust pipe. NH3 and HNCO are generated and mixed with NOx under the condition of high-temperature exhaust. Finally, N2 and H2O are generated in the catalytic reduction reaction of NH3 and NOx. In the case that NO accounts for 90% or even more in NOxof the diesel engine exhaust, the standard SCR reaction plays a dominant role when using SCR system to deal with NOx of the diesel engine exhaust. This reaction can provide high reduction efficiency when the exhaust temperature is between 300 and 450℃. However, the reduction efficiency of NOx will drop rapidly at lower exhaust temperature. So how to improve the reduction efficiency of NOx at lower exhaust temperature is an urgent problem to be solved. Non-thermal plasma （NTP） technology combined with SCR system is one of the most effective means to solve this problem. Active substances, generated in NTP reactor, can oxidize the part of NO from diesel exhaust to NO2 and improve the conversion efficiency of NOx at lower exhaust temperature. The ideal working parameters selected in experiment, can not only increase the concentration of active substances, but also avoid combining main gas components in exhaust such as N2 and O2. A test system of a double-dielectric non-thermal plasma reactor was established to conduct the air discharge test. To study the effect of working parameters on the performance of double-dielectric non-thermal plasma reactor, the changing rules of the volume fractions of NO and NO2 with several parameters such as discharge voltage peak-peak value, discharge frequency and air flow were researched. The results showed that, discharge frequency had great influence on the volume fractions of NO and NO2. Reaction mechanism of air discharge in the NTP reactor changed as discharge frequency changed. The volume fractions of NO and NO2 grew linearly as discharge voltage peak-peak valueincreased, when discharge f
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第14期72-76,共5页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(51306074)
江苏高校优势学科建设工程资助项目(PAPD)
关键词
柴油机
排放控制
尾气排放
介质阻挡放电
低温等离子体
氮氧化物
活性物质
diesel engines
emission control
exhaust gases
dielectric barrier discharge
non-thermal plasma
NOx
active substance
