双介质NTP反应器预氧化柴油机NO的试验研究

Experimental Study on Oxidation of NO from Diesel Engine by Double-Dielectric NTP Reactor

建立双介质低温等离子体(NTP)反应器预氧化柴油机NO台架试验系统,研究了放电电压峰峰值V_(p-p)、放电频率、排气流量及负荷对NTP预氧化NO性能的影响。试验结果表明:2 100r/min转速、0%负荷工况下,相同放电频率时,NO体积分数随V_(p-p)增大而先减小后增大,NO_2体积分数随V_(p-p)增大而增大,NO_x总量随V_(p-p)增大而先减小后增大;不同放电频率时均存在一个能使NO/NO_2比例为1∶1的V_(p-p)临界值点。排气流量对NTP氧化NO性能影响不大。随着负荷的增大,NTP氧化NO的能力逐渐减弱,其中0%负荷和25%负荷时,NTP能使NO/NO_2比例达到1∶1,协同选择性催化还原(SCR)系统可实现快速SCR反应,提高柴油机低温区间NO_x的转化率。

A test system using a reactor of double-dielectric non-thermal plasma（NTP） to pre-oxidize NO from diesel engine was established. The effects of discharge peak to peak voltage （Vp-p）, discharge frequency, exhaust flow and engine load on the performance of NTP＇s pre-oxidizing NO were studied. The results show that, under the working condition of 2 100 r/min engine speed and 0% engine load and with the same discharge frequency, the volume fraction of NO and the total NOx first decrease and then increase as the Vp-p increases ; the volume fraction of NO2 increase with the Vp-p ; among different discharge frequencies, there always exits a critical value of the Vp-p which can make the ratio of NO to NO2 be 1 ： 1. The exhaust flow has insignificant effect on the performance of NTP＇s pre-oxidizing NO. The NTP ability to pre-oxidize NO weakens gradually with the increase of engine load. When the engine load is 0% and 25%, NTP can make the ratio of NO to NO2 reach 1： 1, which helps to speed SCR reaction, thus improving the conversion rate of NOx at low temperature.