基于NSGA-III算法的小管径翅片管式蒸发器高维多目标优化

High-dimensional multi-objective optimization of small-diameter finned-tube evaporators based on NSGA-III algorithm

以稳态分布参数法和NSGA-III算法为基础,提出一种翅片管式蒸发器结构参数与流路参数混合寻优的方法,并依此展开小管径蒸发器结构和流路参数的影响分析与流路的高维多目标设计优化。建立的小管径翅片管式蒸发器模型与实测数据的误差在4%以内,可以较好地用于小管径翅片管式蒸发器的计算。基于该模型进一步建立以结构参数与流路参数为自变量,换热量、制冷剂侧压降、空气侧压降以及成本为因变量的神经网络模型,并利用NSGA-III算法对模型进行优化求解,得到小管径翅片管式蒸发器在一定的结构参数变化范围内的最优结构参数及最佳流路。研究结果显示:管外径对小管径翅片管式蒸发器的换热量、制冷剂侧压降以及成本的影响程度最大;翅片间距对小管径翅片管式蒸发器的空气侧压降影响程度最大;翅片厚度对换热量、制冷剂侧压降、空气侧压降以及成本的影响程度均最小;流路主要影响蒸发器的换热量及制冷剂侧压降;制冷剂流路为二支路、三支路和四支路时,模型可输出综合性能最优的结构及流路特征。

Based on the steady-state distributed parameter method and NSGA-III algorithm,a hybrid optimization method of structural and flow path parameters for finnedtube evaporators is proposed.The impact analysis of structural and flow path parameters of small-diameter finned-tube evaporators,and the high-dimensional multi-objective design optimization of flow path are conducted.For the established model of the small-diameter finned-tube evaporator,the differences between the simulation results and the experimental data are within 4%,thus the model can be used for the calculation of small-diameter finned-tube evaporator.Based on the model,a neural network model with structural parameters and flow path parameters as independent variables,and the heat transfer quantity,the pressure drops of both refrigerant and air sides,as well as the cost as dependent variables is further developed.The NSGA-II algorithm is used to give optimal solution to the structral parameters and flow path in a certain changing range of the structural parameters for the small-diameter finned-tube evaporator.The study results indicate that the tube diameter has the greatest influence on the heat transfer quantity,refrigerant side pressure drop and cost of the small-diameter finned-tube evaporator;the fin spacing has the greatest influence on the air side pressure drop,and the fin thickness has the least influence on the heat transfer quantity,the pressure drops of both refrigerant and air sides,and the cost.The flow path pattern mainly affects the heat transfer quantity and refrigerant side pressure drop of the evaporator.The structure parameters and flow paths with the optimal comprehensive performance can be obtained by the model when the refrigerant flow path with two,three or four branches.