Simulation On Urea-SCR Catalytic Converter Of Diesel Engine And Test Research

The two main pollutants in diesel engine are particular and NOx, and the relationship between them is trade-off. The single inside purification or aftertreatment technology is difficult to reduce both of the PM and NOx. At present,on the basis of optimized combustion ,the Urea-SCR technology can reduce the PM and NOx effectively. For the Urea-SCR, the main content and conclusion of this thesis are:(1)For the different structure of the SCR catalytic converter, the 3D model was built. The fields of the velocity and pressure in the converter were simulated and studied. The results show that the pressure loss is higher than the design value . After adjusting the structure of the converter, the simulation results show that the pressure loss of converter met the design requirement.(2) Based on WEICHAI diesel engine WP10.375, mounted SCR catalyst which is satisfied the demand of pressure loss. Measured NOx emission characteristic and air flow, finished ECS cycle test and measured the emission result without SCR, then calibrate the SCR system based on the emission result. Recheck the engine emission with ESC cycle after calibration, it showed that NOx and PM emission of the engine which mounted the SCR catalyst is satisfied with the CHINA IV emission legislation.(3) To validate the NOx emission related to OBD with calibration and test, successfully achieved the functions of torque limited or alarm when system error and NOx emission exceeded the limit. Studied the mounting and technique requirements of the SCR system which is mounted on the commercial vehicle, finally tested them on the vehicle, the result showed the vibration and reliability of each components are satisfied with the design requirements.