Optimization Of Microchannel Structure And Numerical Study Of Heat Transfer Characteristics Of Nanofluid Flow

With the rapid development of the level of science and technology and processing technology,intelligent,miniaturization,energy-saving and lightweight equipment has been widely used in aerospace,shipping,ocean,automobile and electronics and other major industries.Microelectro mechanical system(MEMS)equipment has become an important part.Its development requires critical design,the most important of which is to effectively remove the heat generated by the electronic components in the MEMS to maintain the service life and reliability of the MEMS equipment.Due to the advantages of microchannel heat sink with good heat dissipation performance,small installation space requirement,light weight and low production cost,it has become an important micro heat dissipation equipment and an important subject of heat transfer and fluid mechanics research.Due to the variety of research directions and methods,and the complexity of research problems,there is no unified law on the heat sink structure of microchannels,which needs further research.In this paper,three different heat sink calculation regions of microchannels are proposed and the physical model of microchannels is established by using SCDM.Discrete thoughts will then use structure different microchannel heat sink area the physical structure of the discrete calculation,at the same time for different calculation area after discrete thermal resistance network model is derived and built and numerical calculation theory and calculation software,Fluent software is used to analyse the different calculation area numerical calculation,and the results of numerical calculation and thermal resistance network model to compare the calculated results,get the most accurate flow characteristic expression and thermal resistance network model,and lay the foundation for follow-up study.Secondly establish the constraint conditions of microchannel section shape size and boundary conditions,with thermal resistance and pressure drop as the optimization goal,with linear weighted sum method and ideal point method respectively derived evaluation method for the theoretical support of square weighted sum method,put forward different evaluation methods and the dimensionless processing,using MATLAB to optimize the tool,using a constrained nonlinear programming problem in the Fmincon function of two kinds of algorithm is optimized,the results of optimization results are obtained and the structural parameters of microchannel flow and heat transfer characteristics of relationship are analyzed.Based on optimization results at the same time puts forward two kinds of different types of sine of the channel,and carries on the parametric modeling with sine channel amplitude and wavelength for the study of the structural parameters of its influence on heat transfer characteristics of flow,at the same time analyzes the nusselt number and the pressure drop along with the Reynolds number,heat transfer enhancement using factor of performance evaluation index and model based on radial basis function(RBF)agent multi-objective genetic algorithm to the optimal selection of channel selection,get good sine channel.On this basis,the microchannel structure of sinusoidal secondary flow channel is proposed and its flow heat transfer characteristics are analyzed,and the performance gain is obtained.Finally,based on previous studies,the thermal and physical properties of nanofluids with different particle types are calculated and solved,and a good experimental correlation formula is obtained.Then the flow heat transfer characteristics in the microchannel of the secondary flow channel were numerically calculated by using the uniform single-phase flow method and the Euler particle flow model of two-phase flow analysis.According to the results of two-phase flow,the correction factor of physical property parameters of uniform single-phase flow is obtained.The heat transfer performance gain of nano-fluid flow in microchannels under different particle types,volume fractions and particle sizes was analyzed by numerical calculation method.At the same time,the flow and heat transfer characteristics of liquid metal in the microchannel were calculated,and the flow and heat transfer characteristics of nano fluid were analyzed and compared to get the best cooling medium in the microchannel.