提高柴油机尿素SCR系统氮氧化物转化效率的试验研究

针对柴油机Urea-SCR后处理系统,为了有效提高NOx转化效率,考虑了包裹保温材料减少排气管散热从而提高载体温度、调整喷嘴位置、安装混合器等3种方法,并进行了不同温度和空速下SCR的NOx转化效率试验。试验结果表明:包裹保温材料能够在ETC循环中提高SCR载体温度20℃左右,从而使发动机更多工况处于SCR催化剂反应高效区域;喷嘴安装在更靠近发动机涡轮出口处(沿排气流反方向移动20 cm后),各工况下NOx转化效率均有所提高;安装混合器后在各工况下NOx的转化效率均有5%左右的提高,尤其在低温220℃时NOx的转化效率提高7%。

Experimental Study on Improving NO, Conversion Efficiency of Urea-SCR System for Diesel Engine

For diesel engine urea-SCR aftertreatment system,the methods of wrapping the thermal insulation material,adjusting the nozzle position and adding the mixer were used to improve the NOx conversion efficiency.Various tests concerning NOx conversion efficiency were carried out at different temperatures and air velocities.The tests results show that the thermal insulation material increases the substrate temperature by 20 ℃ during the ETC test cycle,which makes more engine operating conditions fall into the high NOx conversion efficiency area.When the nozzle is nearer the turbo outlet,which is moved 20 cm in the opposite direction of exhaust flow,the conversion efficiencies under all conditions can be improved.The mixer can improve NOx conversion by 5% in all conditions and even 7% at the temperature of 220 ℃.