CAJ | 학술논문

对装配前置DOC和无DOC的SCR系统柴油机进行稳态和瞬态试验 ,研究了前置DOC在不同循环状态下对NOx 排放的影响.结果表明 :前置 DOC 能显著提高 SCR入口处 NO2 与 NOx 的体积比 V (NO2 ):V (NOx ) ,加速SCR反应 ,提高NOx 转化效率 ,改善NOx 排放 ;在ESC非怠速工况下 ,DOC对V (NO2 ):V (NOx )的影响会随着排气中氧含量和排气温度、空速的提高逐渐降低 ;温度超过一定范围时 ,N H3 对O2 的选择性突然提高 ,V (NO2 ):V (NOx )对NOx 转化效率的影响将减小 ;DOC内氧化反应产生的热量有限 ,不足以提高SCR入口处排气温度 ,而DOC陶瓷载体的储热特性在瞬态循环下会对SCR入口温度产生一定影响 ,但这并不是改善NOx 排放的主要原因.
대장배전치DOC화무DOC적SCR계통시유궤진행은태화순태시험 ,연구료전치DOC재불동순배상태하대NOx 배방적영향.결과표명 :전치 DOC 능현저제고 SCR입구처 NO2 여 NOx 적체적비 V (NO2 ):V (NOx ) ,가속SCR반응 ,제고NOx 전화효솔 ,개선NOx 배방 ;재ESC비태속공황하 ,DOC대V (NO2 ):V (NOx )적영향회수착배기중양함량화배기온도、공속적제고축점강저 ;온도초과일정범위시 ,N H3 대O2 적선택성돌연제고 ,V (NO2 ):V (NOx )대NOx 전화효솔적영향장감소 ;DOC내양화반응산생적열량유한 ,불족이제고SCR입구처배기온도 ,이DOC도자재체적저열특성재순태순배하회대SCR입구온도산생일정영향 ,단저병불시개선NOx 배방적주요원인.
The steady and transient test of diesel engine were carried out under the conditions of pre-DOC and non-DOC and the effect of pre-DOC on NOx emission was studied .The results show that the pre-DOC can obviously increase the V (NO2 ):V (NOx ) volume fraction ratio st SCR entrance ,accelerate the SCR reaction ,raise the conversion efficiency of NOx and improve NOx emission .Effect of DOC on V (NO2 ):V (NOx ) volume fraction ratio decreases with the increase of oxygen content ,ex-haust temperature and air speed in ESC except idle .When the exhaust temperature exceeds a certain range ,the effect of V (NO2 ):V (NOx ) volume fraction ratio on NOx conversion rate decreases due to the sharp increase in the selectivity of NH3 to O2 .The limited heat of DOC reaction is not enough to increase the entrance temperature of SCR ,but the accumulated heat of ceramic substrate can increase the entrance temperature in ETC ,however it is not the main method to improve NOx emission .