Design and Experimental Study of a New SCR Urea Nozzle

With the rapid development of the economy, the number of car ownership has increased rapidly, and a large amount of exhaust emissions have caused serious harm to people and the environment. Selective Catalytic Reduction (SCR) technology adapting to China's national conditions has achieved rapid development. The core component of SCR system is urea nozzle. This paper analyzes the structure of two urea nozzles (Bosch and Tenneco), and designs a new type of centrifugal urea nozzles. The nozzle flow passage is designed and the force of the valve core is analyzed. The length- diameter ratio of the nozzle hole is determined through experiments. And an experimental system was built to analyze the spray characteristics and control characteristics of the nozzle. Experiment shows that the nozzle flow under the rated pressure (0.9 MPa) was 9.15 L/min , atomizing Angle remain at around 30
^°
, mist particles diameter of 82 μm. By changing the urea nozzle PWM control timing diaaram , the electromagnet can be sucked successfully and maintain the suction state under the action of one pulse. At this time, the power-on time is proportional to the flow rate in the range of 0.7% -98%.