柴油机Urea-SCR系统耦合控制研究

摘要

In order to reduce the NO x emissions and NH3 leakage effectively ,the double closed-loop control of urea-SCR sys-tem for diesel engine was proposed based on the NOx and NH3 sensors and the coupling control of NH3 adsorption ,desorption and coverage rate in the catalytic converter was realized .Based on the NH3 active model ,the control strategies of urea-SCR double closed-loop control were determined ,the correction methods of urea injection quantity and ammonia storage quantity were put forward ,and the control accuracy and robustness improved effectively .According to the ESC and ETC regulations , the experiments of NOx conversion efficiency ,urea injection amount ,NH3 leakage and emission certification were carried out . The results show that the double closed-loop control of urea-SCR system can solve the delay of NH3 control signal and has reli-able performance and good control accuracy .Accordingly ,the NOx emission and NH3 leakage can meet state V standard with the control method .%为有效降低NOx 排放和NH3泄漏量，提出了基于NOx 和NH3传感器的柴油机SCR双闭环控制系统，实现了对催化转化器内部的N H3吸附、解吸附与覆盖速率的耦合控制。基于催化转化器内部的N H3活化模型，制定了尿素SCR系统双闭环耦合控制策略，提出了尿素喷射量和储氨量的修正算法，有效地提高了 U rea-SCR双闭环系统的控制精度和鲁棒性。依据柴油机ESC和ETC循环测试法规，进行了NOx 转化效率、尿素喷射量、NH3泄漏和排放达标等试验。结果表明：该柴油机SCR双闭环控制系统有效解决了N H3浓度控制信号延迟问题，性能可靠，控制精度高，柴油机NOx 排放和NH3泄漏量达到国Ⅴ排放标准。