SCR催化器内浓度场影响因素的仿真研究

发布时间：2018-05-16 17:33

本文选题：选择性催化还原 + 浓度场　；参考：《车用发动机》2016年05期

【摘要】：为提高NO_x的转化效率,研究了温度、空速、氨氮比和NO与NO_2的摩尔比对SCR催化器内浓度场的影响。试验验证了SCR化学反应模型,将准确的化学反应动力学参数输入到Fire软件并建立SCR催化器模型,计算分析SCR催化器内组分浓度场的影响因素。得出以下结论:温度越高,NH_3和HCNO的浓度越高;流体涡流为喷雾液滴蒸发和热解提供了有利条件;空速太大,NO的转化效率会降低;当氨氮比为1时,理论上NO_x的转化效率达到最高;当氨氮比小于1时,NO_x转化效率随氨氮比的升高而升高,但在接近1时候产生氨滑移;当氨氮比大于1时,NO_x转化效率变化不大但会产生大量氨滑移。因此最佳的氨氮比应是在保证较小的氨滑移的前提下尽可能提高NO_x转化效率。
[Abstract]:In order to improve the conversion efficiency of NO_x, the influence of temperature, air velocity, ammonia nitrogen ratio and the molar ratio of NO and NO_2 on the concentration field in the SCR catalytic converter was studied. The experiment verified the SCR chemical reaction model. The exact chemical reaction kinetic parameters were input to the Fire software and the SCR catalyst model was established, and the influence of the concentration field in the SCR catalyst was calculated and analyzed. The following conclusion is drawn: the higher the temperature, the higher the concentration of NH_3 and HCNO; the fluid swirl provides favorable conditions for the evaporation and pyrolysis of spray droplets; the conversion efficiency of NO will be reduced when the velocity of air is too large; when the ratio of ammonia to nitrogen is 1, the conversion efficiency of NO_x reaches the highest, and the conversion efficiency of NO_x increases with the increase of ammonia nitrogen ratio when the ratio of ammonia to nitrogen is less than the ratio of ammonia to nitrogen. However, the ammonia slip is produced near 1. When the ratio of ammonia to nitrogen is greater than 1, the conversion efficiency of NO_x changes little but produces a large amount of ammonia slip. Therefore, the best ammonia ratio should be as much as possible to improve the conversion efficiency of NO_x under the premise of ensuring a smaller slip of ammonia.

【作者单位】：吉林大学汽车仿真与控制国家重点实验室;
【基金】：国家自然基金资助项目(51306070)
【分类号】：TK423

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