| High-tech science and technology continue to develop,and industry has made great progress,especially the in-depth development of aerospace and computer technology,which has set higher requirements for the safe and stable operation of equipment.There are some high-heat components in these devices.How to cool high-heat components such as high-power integrated circuits and turbine blades has become a research hotspot.On the other hand,the introduction of micro computer system MEMS has accelerated the research on micro heat exchangers.A high-power microchannel heat exchanger(microchannel heat sink)was studied.Firstly,the basic research status of microchannel heat sink is introduced,including three aspects: change of cross-sectional shape,change of working fluid and research on roughness.At the same time,the flow characteristics and energy transfer of t he microchannel heat sink are briefl y introduced,and the scale effect is roughly summarized and explained.The research status of fractal geometry is introduced,the concept of fractal dimension is explained mathematically,and the matlab program of two-dimensional fractal function is developed.The fractal function curves were compared using two important parameters affecting the fractal function curve as variables,and the influence of the characteristic coefficient and fractal dimension on the shape of the curve was found,which laid the foundation for the subsequent model establishment.The governing equations and energy governing equations in fluid dynamics are derived,and the basic boundary conditions are determined.Some parameters for measuring heat transfer and flow characteristics and their calculation formulas are introduced.Based on two modeling ideas,the aspect ratio of the micro-single-layer straight channel heat sink was modeled.The calculated results were analyzed qualitatively,a nd two design variables and their ranges were determined.The basic idea of the response surface method is introduced,and the two design variables mentioned above are introduced.The experimental design is based on the inlet and outlet pressure drop and temperature difference.The mathematical model of the response surface is established by software Design Expert.Two quadratic polynomials.The accuracy of the mathematical model is analyzed,and the accuracy is found to be high.The coefficients of the qua dratic polynomial are analyzed,and the polynomial coefficients are found to be highly significant,which can well express the relationship between the design variables and the response values.The micro-channel rough element is studied.By controlling the height and spacing of the regular rough elements,the characteristic coefficients of the rough elements and the equal interval of the fractal functions,the flow and heat transfer characteristics of the rough channels on the microchannels were studied,and the model was calculated with four Reynolds numbers.The effects of rough element height,rough element spacing,rough element spatial position,Reynolds number,and rough element shape on flow and heat transfer characteristics are discussed.A comparative study of the arrangement of the spoiler columns,the horizontal and vertical spacings,and the special-shaped spoiler columns was conducted,and it was found that the fork row arrangement has better heat transfer performance than the parallel arrangeme nt.The lateral spacing has a greater influence on the flow characteristics than the longitudinal spacing.In the study of the special-shaped spoiler,it was found that the drop-shaped spoiler has a great promotion effect on the heat transfer performance.The wing-shaped spoiler has a minimum pressure loss while increasing a certain heat transfer capacity. |
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