基于多目标优化的柴油机VNT–vEGR系统开发研究

为了在兼顾柴油机经济性和颗粒物排放的前提下,进一步降低氮氧化物(Nitrogen oxides,NO_x)排放以实现良好的柴油机综合性能,设计带文丘里管废气再循环系统的可变涡轮增压系统(Variable nozzle turbo+Venturi-exhaust gas recirculation,VNT+vEGR)。针对排气旁通阀涡轮增压(Wastegate,WG)柴油机原机,进行文丘里管废气再循环系统(Venturi-exhaust gas recirculation,v EGR)的设计和与可变涡轮增压器(Variable nozzle turbo,VNT)的匹配研究,并进行经济性、氮氧化物和颗粒物排放仿真计算研究。应用试验设计方法技术(Design of experiment,DoE)对VNT-vEGR系统进行多目标优化研究。研究结果表明,相比于配备排气旁通阀涡轮增压器的柴油机原机,对VNT-v EGR系统柴油机应用Do E进行多目标优化匹配后,欧洲稳态测试循环(European steady-state cycle,ESC)工况加权油耗值基本保持不变,氮氧化物加权排放量下降约49.5%,能够实现良好的综合性能。

Study on the Development of Diesel Engine VNT-vEGR System Based on Multi-objective Optimization

In order to achieve better comprehensive performance which further reduces the nitrogen oxides(NOx)emission of diesel engine while maintain fuel efficiency and soot emission, a system that combines variable nozzle turbo and Venturi-exhaust gas recirculation(VNT+vEGR)is designed. For a wastegate(WG)original turbocharged diesel engine, the design of Venturi-exhaust gas recirculation(vEGR)system and the matching of variable nozzle turbo(VNT)system are conducted. And the study of simulation on the brake specific fuel consumption(BSFC), NOx and Soot emission is carried out. The VNT-vEGR system is optimized by design of experiment(DoE)multi-objective optimization method. The results indicate that compared with the original WG diesel engine, ESC weighted value of fuel consumption of optimized VNT-vEGR system basically remain unchanged, and weighted value of NOx emission decrease by 49.5%. It can be concluded that the diesel engine have achieved good comprehensive performance.