Design And Heat Transfer Performance Of Microchannel Heat Sink For High Power Micro Devices

With the rapid development of microelectronics technology,the development of electronic components gradually tends to miniaturization,high integration and high sensitivity,which will lead to severe challenges in the thermal management of high-power micro devices.Microchannel heat dissipation technology is considered to be one of the effective ways to solve the heat dissipation problem of high-power micro devices.Compared with conventional heat dissipation technology,microchannel heat dissipation technology has the advantages of small volume,light weight,low noise and high heat transfer coefficient.This paper focuses on high-power micro devices combined with the jetting impingement effect,a compact direct impingement microchannel heat sink is designed,and the flow and heat transfer performance of the direct impingement microchannel heat sink are experimentally and numerically studied in the range of0.4L/min to 2.0L/min volume flow and maximum heating power of 318W.The main research contents and conclusions were illustrated as follow:(1)By setting pressure sensors at the inlet and outlet of the heat sink,the pressure data under different flow rates are recorded.The results show that when Q=2.0L/min,the pressure drop in the microchannel is about 2.2k Pa.The pressure drop in the microchannel accounts for about 30%of the total pressure drop,and the other pressure drops are caused by the connecting pipe,inlet and outlet loss and the sudden change of flow direction.When Re=450,the flow state in the channel begins to change from laminar to turbulent.(2)In the process of heat transfer,the surface temperature of the heating head,the surface temperature of the heat sink base,the fluid inlet and outlet temperature and other parameters under various working conditions are recorded.The heat transfer resistance,heat transfer coefficient and Nusselt number of the heat sink are calculated through the formula,and compared with the predicted values of the empirical relationship in other literature.The results show that when the fluid flow rate is 2.0L/min,the total heat transfer coefficient reaches 50×10~3W/m~2·K,convective heat transfer coefficient is21.5×10~3W/m~2·K.Even when the maximum heating power is 318W,the surface temperature of the heating head is controlled below 65℃and the temperature distribution is uniform.The effectiveness of microchannel extension is verified by comparing the thermal resistance in vertical and horizontal directions.(3)In order to study the local heat flow and heat transfer coefficient,using COMSOL software and based on the finite element method,a three-dimensional conjugate heat transfer numerical model of convective heat transfer and substrate heat conduction in microchannel is established.The symmetrical calculation domain of single microchannel is numerically simulated,and the simulated data are verified with the experimental data.The results show that the simulated data are basically consistent with the experimental data.The local heat transfer coefficient gradually increases along the flow direction in the jetting region,gradually decreases outside the jetting region,and finally tends to be stable outside the heating region.The influence of the central jetting impingement region on the enhanced heat transfer is also analyzed.It is found that when Q=1.0L/min,the jetting impingement effect enhances the heat transfer effect of the microchannel by about 15%.