汽车尾气温差发电系统车载兼容性多目标优化研究

Research on Multi-objective Optimization of Vehicle Compatibility of Automobile Exhaust Thermoelectric Generator Systems

汽车尾气温差发电系统在接入发动机的排气管时会改变其气流,为了尽可能降低对发动机原有性能的影响,提高汽车尾气温差发电系统的发电性能,针对汽车尾气温差发电用六边形热交换器,以表面平均温度最高和压力损失最小为目标进行其车载兼容性优化。基于CFD软件搭建了热交换器的有限元仿真模型,研究热交换器的入口气体流速对其表面温度和压力损失的影响,以及入口气体温度对其表面温度的影响,以翅片长度、角度、宽度及翅片间的间距为设计变量,针对试验数据建立高斯过程回归代理模型,并采用灰狼算法在多目标优化函数空间中寻求最优解。结果表明,与经典的NSGA-Ⅱ算法相比,利用多目标灰狼算法进行优化时所得Pareto解集更为集中,设定的评价指标值也更高;与优化前的几种结构相比,优化后的热交换器表面平均温度有所降低,但压力损失下降显著;与空腔结构热交换器相比,其表面平均温度和压力损失均有提升,压力损失增加幅值在可接受范围内,证明优化后的热交换器能有效兼顾汽车尾气温差发电系统的功率及其车载兼容性。

When the automobile exhaust thermoelectric generator system was connected to the ex-haust pipe of the engine,the airflow would be changed.In order to minimize the impacts on the origi-nal performance of the engines and improve the electrical power generation performance of the auto-mobile exhaust thermoelectric generator systems,a hexagonal heat exchanger used for an automobile exhaust thermoelectric generator system was optimized for the on-board compatibility with the goal of the highest average surface temperature and the smallest pressure loss.A finite element simulation model of the heat exchanger was built based on CFD software to study the influences of the inlet gas speed of the heat exchanger on the surface temperature and pressure loss,as well as the influences of the inlet gas temperature on the surface temperature.The fins length,fins angle,fins width and fins spacing were taken as the design variables.The Gaussian process regression proxy model was established based on the test data,and the grey wolf algorithm was used to obtain the optimal solution in the multi-objec-tive optimization function space.The results show that compared with the classical NSGA-Ⅱalgorithm,the Pareto solution set obtained by multi-objective grey wolf algorithm is more concentrated and the evaluation in-dex is higher.The optimized heat exchanger with multi-objective grey wolf algorithm has a lower surface av-erage temperature than that of several structures before optimization,but the pressure loss is significantly re-duced.Compared with the cavity structure heat exchanger,the surface average temperature and pressure loss of optimized heat exchanger increase,and the pressure loss increasing amplitudes are within the acceptable ranges.The optimized heat exchanger may effectively take into account the power generation of the automo-bile exhaust thermoelectric generator systems and the on-board compatibility.