中文摘要：

根据发动机稳态工况下的氮氧化物（NOx）转化率试验发现了NOx转化效率峰值现象,通过分析从理论上解释了该现象。根据NOx转化效率峰值现象,提出了尿素选择性催化还原（urea-SCR）系统周期性喷射设想。设计试验,通过对比自主urea-SCR系统周期性喷射策略与商业urea-SCR喷射策略的试验结果,发现urea-SCR系统周期性喷射在NOx转化效率、尿素喷射量、氨泄漏及尿素能效比等方面均有显著改善,对优化urea-SCR系统尿素喷射控制策略有重要意义。

英文摘要：

The phenomenon of a peak NOx conversion efficiency found in a test for NO~ conversion under engine steady-state condition was analyzed theoretically. A periodic injection control strategy for a urea-SCR system was put forward based on this phenomenon to promote NOx conversion efficiency. A test was designed and the comparison was made of the proposed urea-SCR periodic injection control strategy and a commercial urea-SCR injection control strategy. The result shows the former strategy has a remarkable improvement in terms of NOx conversion efficiency, urea injection dosing, NH3 slipping, and energy efficiency to urea ratio, which has a great significance in optimizing the injection control strategy of a urea- SCR system.