CO_2浓度和排气温度对LNT吸附路径的影响

Influence of CO_2 concentration and exhaust temperature on adsorption path of LNT

为了研究稀燃汽油机在150~400℃范围内排气中CO_2浓度和温度对吸附路径的影响,改写了稀燃NO_x捕集器(LNT)相关的气相、表面相和热力学文件,运用Chemkin软件建立了包含硝酸盐和亚硝酸盐两种吸附路径的LNT模型。研究结果表明:CO_2对两种吸附路径均有影响,对亚硝酸盐路径的抑制作用强于对硝酸盐路径的影响,但随CO_2浓度增加,抑制作用逐渐减弱;排气温度比CO_2浓度对两种路径有更显著的影响;在150~200℃低温区,NO的氧化和亚硝酸盐的进一步转化均受阻,故亚硝酸盐路径主导;在高温区300℃和400℃时,两种路径占有率相似。

The gas file,surface file and thermal file of LNT in chemkin were rewritten,and the adsorption model of lean NOx trap(LNT),which included two kinds of adsorption paths,was developed to investigate the influence of CO2 concentration and temperature of lean burn gasoline exhaust on the adsorption path from 150 to 400℃.The main research results show that the presence of CO2 has influence on the both paths,and CO2 has more inhibition on nitrite path than nitrate path.With the concentration of CO2 increasing,the effect of inhibition weakens.The influence of exhaust temperature on both of the paths is more significant.During low temperature 150-200℃,nitrite path is major path because of the inactivation of nitrite evolution and NO oxidation.While at the high temperatures of 300℃and 400℃,two paths have similar occupancy.