乙醇选择性催化还原NOx后处理系统在重型柴油机上的应用研究

选择催化还原是解决稀燃条件下NOx排放问题的主要技术之一。在发动机台架上对以乙醇作为还原剂的Ag/Al2O3催化剂特性进行了试验研究,对Ag/Al2O3 Cu/TiO2和Ag/Al2O3 Cu/TiO2 Pt/TiO2两种还原、氧化催化剂组合进行了对比分析。分析表明,Ag/Al2O3 Cu/TiO2 Pt/TiO2催化剂组合具有较好的去除NOx并抑制THC和CO排放升高的综合性能。整个后处理系统安装在一台排量为5.12 L的柴油机上,采用开环控制策略对乙醇喷射进行控制,在ESC测试工况下,NOx转化效率为64%,THC和CO排放基本保持原机水平。最后通过对乙醇喷射控制策略的进一步改进,使THC和CO排放得到了改善。

Application of Nox-SCR Aftertreatment System to the HD Diesel Engine Using Ethanol as a Reductant

Selective catalytic reduction(SCR) is one of the most promising technologies for removing NOx in lean conditions.In this paper,the Ag/Al2O3 catalyst using ethanol as a reductant was investigated on the test bench.Further more,two different catalyst assemblies,Ag/Al2O3 Cu/TiO2 and Ag/Al2O3 Cu/TiO2 Pt/TiO2 were analyzed.It's found that Ag/Al2O3 Cu/TiO2 Pt/TiO2 can reduce lean NOx with ethanol effectively and sufficiently lower the THC and CO emission.Finally,the whole NOx aftertreatment system was mounted on the 5.12 L diesel engine.An open-loop control strategy was used to control the injection of ethanol,which obtained 64% reduction of NOx on the 5.12 L diesel engine without much increasing the THC and CO emission.With the improvement of the control strategy,the THC and CO emission were further reduced.