重型柴油机NO_x尿素SCR混合器的设计与试验研究

设计了2种紧凑型混合器,分别为带4个叶片的混合器1和带4组叶片对(8个叶片)的混合器2。试验用U型管和傅里叶变换红外光谱仪研究了混合器对压力损失和NOx转化效率的影响。试验结果表明:排气流量、排气管管径对压力损失影响较大,而温度对压力损失影响较小;混合器2的压力损失比混合器1的小;混合器使NOx转化效率最大提高约10%;混合器安装在喷嘴后端比安装在喷嘴前端时的NOx转化效率高;无混合器时外径63mm排气管对应的NOx转化效率比外径76mm排气管对应的NOx转化效率提高约8%。

Design and Experiment of Mixer in NO_x Urea-Selective Catalyst Reduction System for Heavy Duty Diesel Engine

Two compact mixers separately with four blades(No.1 mixer) and four couples(eight blades total) of blades(No.2 mixer) were designed.Pressure loss and NOx conversion ratio were studied using U tube and Fourier transform infrared(FTIR) spectroscopy.The experiment results show that exhaust gas mass flow and exhaust pipe diameter have significant effect on the pressure loss while gas temperature has slight influence;the pressure loss caused by No.1 mixer is larger than No.2 mixer;both two mixers can improve the NOx conversion efficiency at most about 10%;the mixer mounted downstream of the injector has better mixing effect than that mounted upstream;in the case of no mixer,the 63 mm outer diameter exhaust pipe gets higher NOx conversion efficiency than that of 76mm outer diameter by about 8%.