紧耦型SCR催化器混合段的性能研究

Performance of Mixing Section of Coupling Type SCR

应用Fluent软件对紧耦型SCR催化器两种混合段方案进行压力损失、温度场、速度场分析,在发动机台架上进行两种混合段方案的转化效率试验、压力损失试验、排放循环试验、氨泄漏试验。分析与试验结果表明:单层管混合结构的速度均匀性为0.97,压力损失为9.32kPa,均好于双层管混合结构,后者的速度均匀性为0.948,压力损失为10.82kPa;两种混合段方案的温度场分析结果一致,且瞬态排放循环WHTC结果都能满足国家要求,但低温工况时,双层管结构SCR的转化效率和氨泄漏情况明显好于单层管结构SCR,瞬态排放循环WHTC过程中双层管混合结构的氨泄漏体积分数峰值为29.5×10-6,平均值为4.2×10-6,而单层管混合结构的氨泄漏体积分数峰值高达263×10-6,平均值为15.8×10-6。

The pressure loss ,temperature field and velocity field for two kinds of mixing section of coupling type SCR were analyzed with the FLUENT software and the corresponding conversion efficiency test ,pressure loss test ,emission cycle test and ammonia leakage test were conducted on the engine test bench .The analysis and test results show that the velocity uni-formity and pressure loss for single pipe structure is 0 .97 and 9 .32 kPa respectively and is better than 0 .948 and 10 .82 kPa for double pipe structure .The temperature fields for both mixing schemes are almost the same and their WHTC emission can meet the national requirements .At low temperature conditions ,the ammonia leakage and NOx conversion for double pipe structure are better than those for single pipe structure . The ammonia leakage peak and average value for double pipe structure is 29 .5 × 10-6 and 4 .2 × 10-6 ,while those for single pipe structure is 263 × 10-6 and 15 .8 × 10-6 respectively .