Papers by Author: Ping Qi

Abstract: Open-loop control strategy of SCR urea injection system for MD/HD vehicle diesel engine is established firstly in this paper. Then the emission test is performed for a domestic diesel engine in test bench. Test results show that NO_X emissions of ESC and ETC are much lower than the limit values of National-IV emission regulation under a simple injection strategy. The results also show that the urea solution consumption accounts for only 5.8% of the fuel consumption. What’s more, the tests have been accumulated for achieving accurate matching between urea injection and diesel engine.

Abstract: A three-dimensional model of a diesel Urea-SCR（Selective Catalytic Reduction）catalytic converter system was set up with aid of CFD software AVL FIRE coupled with available knowledge of SCR chemical reaction kinetics. Basing on the validation of the spray injection model of Urea-water-solution, the numerical simulation was made to get the distribution of pressure, velocity, temperature and species concentration in the converter and NO_x conversion in different conditions by considering the injection and evaporation of the urea-water-solution, the thermal decomposition and hydrolysis into ammonia and the surface catalytic reactions in the monolith. The simulated results have some reference meaning for improving NO_x conversion efficiency and optimizing the diesel SCR catalytic converter.

Abstract: In this paper, the Urea-SCR system is first introduced; then change of the urea solution concentration under different temperatures with time lapsing is given. Meanwhile, conditions for the urea crystallization are analyzed and SCR converter adaptability is tested under high sulfur environment on engine test bench. As the efficiency of NOx conversion is not significantly reduced after aging and the activity of the catalyst is very little damaged by dense sulfur content in fuel, SCR catalyst is able to adapt to the application of high-sulfur-contained fuel environment in our country.