Simulation And Experimental Research Of SCR Urea Injection System Of Diesel Engine

As the public pay more and more attention to the environment issues, the diesel engine emission regulations become stricter increasingly. So it's urgent to reduce the diesel's exhaust gas in order to meet the requirement of emission regulations. And the selective catalytic reduction post-processing technology is considered as the main technology that can make diesel meet the V emission regulation among all technologies which can effectively reduce the exhaust gas produced by diesel engine nowaday. The SCR technology which is based on the principle of nitrogen oxygen reduction inject with moderate urea aqueous solution according to the oxynitride content in the exhaust gas and then carry out a reduction reaction in the oxynitride and produce harmless nitrogen and water into air.So the key point of SCR after-treatment technology is how to control its urea injection quantity accurately.My paper has completed to design a SCR urea injection system which adopts a combination of fixed differential pressure and variable time with no air auxiliary technology to control its injection quantity after doing some research and analysis on the development, design concept and structure characteristic of domestic and overseas SCR urea injection system.This plan means that the injection quantity is up to its injection time and the injection pressure should be constant during the injection process.And this system is equipped with urea supply, pressure regulation and stabilization, and filter function,and my paper also has completed the component design and selection according to the design requirements.Then the paper creates a SCR urea injection system model and finish simulation analysis and some research on changing parameters on its performance based on AMESim software. The simulation results demonstrate that the SCR urea injection system is provided with good linear characteristic and atomization ability, and at the same time it can control its injection quantity accurately according to the injection quantity curve under different parameters.At last, the paper conducts bench test of the SCR injection system model in order to verify its feasibility. The main tests are as below:(1) Setting the same parameters and complete test and then compare the test result with simulation result,the high accordance of comparison result proves that the simulation is reasonable,so we can confirm the optimization measures for SCR injection system model from simulation is meaningful and it can provide injection strategy guiding..(2) Do the nozzle atomization test under the pressure from 3 bar to 9 bar,the test result reveals that the better atomization ability the higher pressure.