Research On Structural Optimization And Flow And Heat Transfer In A Vertical Jet Microchannel

With the rapid development of VLSI,thermal management had become a challenging research field.In the past decades,thermal management technology had played a key role in controlling component temperature to ensure equipment performance and reliability.Therefore,in order to solve the problem of efficient and stable heat dissipation of electronic equipment,it is very important to carry out the research on the heat dissipation direction of electronic equipment.Compare with traditional channels,microchannels have the advantages of compactness,miniaturization and high heat flux.Therefore,microchannels can better adapt to the development trend of highly integrated electronic devices.Because the jet impinges directly on the plane,the boundary layer becomes thinner and enhances the effect of convective heat transfer,the jet impingement structure has always been considered as a better way to solve the problem of heat dissipation with high heat flux.In order to give full play to the advantages of microchannel and jet impact structure,microchannel and jet impact are combined to form jet microchannel heat dissipation technology.In the study of jet microchannel,the jet impact structure was arranged along the length of microchannel.In order to study the influence of the arrangement of the jet structure along the width of the microchannel on the jet microchannel,a jet microchannel radiator with the jet structure arranged along the width of the channel was proposed,the 3D structure diagram and specific size parameters of the radiator were given,and relevant research was carried out.Firstly,the single-phase flow of jet microchannel radiator was studied.The numerical simulation method of single-phase flow in jet microchannel was introduced,the reliability of single-phase flow model was verified,and the simulation results of single-phase flow were obtained.According to the results of single-phase flow numerical simulation,the flow and heat transfer characteristics of single-phase flow in jet micro radiator were analyzed and compared with traditional rectangular microchannel.Taking the pumping power and thermal resistance as the evaluation indexes,the four dimensionless parameters of the radiator structure(the ratio of the height of the baffle from the bottom to the inlet width α、channel section ratio β、ratio of fin width to channel width γ、ratio of baffle width to inlet width δ)were analyzed,the optimum value of the radiator structure in the research range was obtained.The performance of microchannel radiator with jet structure transverse arrangement was compared with that of microchannel radiator with jet structure in references.Based on the above contents,the two-phase flow process of jet microchannel was numerically simulated.The reliability of the two-phase flow model was verified by the numerical simulation of the two-phase flow in the microchannel.The typical flow pattern of gas-liquid two-phase flow in jet microchannel was studied,and the formation process of the typical flow pattern was analyzed.The two-phase flow of the shrinking jet microchannel was simulated.By comparing the two-phase simulation results with the vertical jet microchannel,the two-phase distribution and flow characteristics of the shrinking jet microchannel radiator were analyzed.Based on the two-phase distribution at the bottom of the channel,the velocity distribution at the bottom of the channel and the two-phase distribution near the inner wall,the effects of the transverse contraction distance and the longitudinal deflection distance of the baffle on the contraction jet microchannel were analyzed,and the optimal values of the transverse contraction distance and the longitudinal deflection distance of the baffle were given.Compared with the traditional rectangular microchannel,the thermal resistance and pump power of the studied jet microchannel were much lower than those of the traditional rectangular microchannel;The value of the ratio of baffle height from bottom to inlet width α is 1,the value of the channel section ratio β is 6,the value of the ratio of fin width to channel width γ is 0.5,and the value of the ratio of baffle width to inlet width δ is 0.25,were the best value in the study range;Compared with the jet microchannel in the literature,the microchannel radiator with transverse jet structure can further reduce the thermal resistance while maintaining low pump power.Compared with the vertical jet microchannel,the contraction jet microchannel had the characteristics of concentrated gas phase distribution,long continuous gas distance from the inner wall,large two-phase flow velocity,small two-phase flow basin,long two-phase flow path and concentrated two-phase flow velocity;The longitudinal deflection distance at the end of the baffle had little effect on the two-phase distribution and flow characteristics,and the transverse contraction distance at the end of the baffle had a great effect on the two-phase distribution and flow characteristics.Through comprehensive analysis,the best values of longitudinal deflection distance and transverse contraction distance at the end of baffle in the research range are 8 times of baffle width and 1 time of baffle width respectively.