Research On Multi-Objective Optimization Designand Enhanced Heat Transfer Of Microchannel Heat Dissipation Structure Based On NSGA-Ⅱ Algorithm

The micro-channel heat dissipation structure is a major means of modern heat dissipation technology.Excellent structural design can improve the heat dissipation performance of the micro-channel heat sink,improve temperature uniformity,and balance the performance requirements and manufacturing and use costs of the heat sink.In this paper,based on the bionic structure design,combined with the turbulence structure to design the heat dissipation channel,the multi-objective optimization algorithm and decision-making algorithm are used to optimize the structural parameters to obtain the optimal performance parameters,and a variety of materials are used for the multi-channel coupling structure.Enhanced heat transfer research.The main work of the paper is as follows:（1）Design a new type of micro-channel heat sink that combines the capillary bionic heat dissipation flow channel with the forward and reverse Tesla turbulence structure.ANSYS CFX thermal simulation results show that:compared with the traditional capillary cooling channel and the forward and reverse Tesla valve combined with capillary structure,the pressure drop in the channel is reduced by 8.583%and 23.584%respectively;the reverse structure The heat transfer coefficient is higher,the value is 1498.47 Wm^-2K^-1,and has a lower thermal resistance of 0.1437K/W,and has a lower minimum temperature of the solid domain Ts_min is46.34℃.This conclusion shows that the reverse Tesla valve turbulence structure can greatly enhance the heat dissipation performance of the bionic capillary heat dissipation channel,but it needs to consume more pumping power.（2）In order to balance cost and performance,this study uses the multi-objective optimization algorithm（Non-dominated Sorting Genetic Algorithm-II,NSGA-II）based on the MATLAB platform on the basis of the bionic cooling channel structure to carry out the five structural design parameters Optimization to obtain the Pareto optimal frontier between two objective functions(the lowest temperature in the solid domain Ts_min,pumping power P_p);and use the TOPSIS decision algorithm to evaluate the structure Parameter design plan,given the ranking of the plan,and comparing the optimal group with the initial group,it is found that Ts_minis reduced by 20.1%after optimization;P_p is reduced by 36.74%after optimization.This conclusion shows that the multi-objective optimization algorithm can effectively optimize the structural parameters of the heat dissipation channel,and can maintain the balance between the performance and cost of the heat sink.（3）Using the BP neural network algorithm to build the SPSSPRO prediction model,the structural parameters are controlled in a specific range to obtain good heat dissipation performance and lower operating costs.When the 5 structural parameters（number of branches,number of valves,groove width,groove depth,and valve radius）are controlled outside the parameter range of 5,4,5 mm,4 mm,and 5 mm,a smaller objective function Ts_min is lower than 50°C,that is,the heat dissipation performance and temperature uniformity of the heat dissipation structure are better;this shows that when the structural parameters are designed above this range,the heat dissipation performance of the microchannel heat sink is better;When the values of the five structural parameters are within the intervals of 9,8,9 mm,8 mm,and 8 mm,the smaller objective function P_p is lower than 90 W;this indicates that when the structural parameters are designed within this range,the structural consumption Less external energy and lower operating costs.（4）Design multiple groups of triangular heat dissipation channel coupling structures,and conduct enhanced heat transfer research on them.The experimental results of the Fluent module of ANSYS software show that different coupling methods between multi-layer flow channels can effectively improve the heat transfer performance;in the study of enhanced heat transfer,when the porous material area is increased,the heat dissipation performance and temperature uniformity are both effectively improved.improve.In addition,taking the parallel arrangement structure of triangular channels as an example,when the fluid changes from pure water to 1%volume fraction of nanofluid,the heat transfer coefficient increases by 630.55%;when the volume fraction of nanofluid increases from 1%to 2%,the heat transfer coefficient The heat coefficient increased by 10.07%;when the phase change material layers were 5 mm,10 mm,and 15 mm,the heat transfer coefficients increased by 344.16%,429.93%,and 522.326%,which indicated that the nanofluid working medium and phase change materials were both Can greatly enhance the heat transfer performance.