Study on modeling and simulation of control strategy for urea-SCR system of heavy duty diesel engine

Aimed at selective catalytic reduction (SCR) system of heavy-duty diesel engine, the mathematic control of each component inside a catalytic converter was deduced based on the law of conservation of energy and mass. Furthermore, models of SCR catalytic converter, SCR open-loop control strategy and SCR close-loop control strategy were established with the software of MATLAB/Simulink. Except specific conditions, the simulation result of NOx conversion in SCR open-loop strategy is in agreement with the experiment one under the ESC cycle and the error is controlled within 10%. As to the SCR close-loop control strategy, though the NOx conversion efficiency does not increase obviously under the ETC cycle, the average and peak of NH3 slip decrease significantly, and the average value of NH3 slip is sixty percent of that of the open-loop control strategy. ©, 2015, Chinese Society for Internal Combustion Engines. All right reserved.