Study On Heat Transfer Performance Of Vapor Chamber With Super Hydrophobic Surfac

With the continuous development and progress of microelectronics technology,miniaturization,high performance,integration and high power consumption are the inevitable development trend of electronic products,which will inevitably lead to the rapid rise of the temperature trend of electronic products in daily work and the constant increase of the heat flux inside the system.Therefore,it is a hot topic to optimize and improve the cooling system of electronic components.Surface hydrophobic treatment can change the condensation mode from filmwise condensation to dripwise condensation,thus significantly improving the heat transfer coefficient of condensation.In this paper,the copper surface was treaded by chemical etching and hydrophobic modification.By studying the reaction conditions of etching and modification,the best method to prepare superhydrophobic copper surface was found.The superhydrophilic copper surface,smooth copper surface and superhydrophobic copper surface were prepared,and the heat transfer performance of the three surfaces was analyzed through the visualized steam condensation heat transfer experiment.On this basis,the superhydrophobic surface is successfully applied to the condensation of the vapor chamber,which improves the heat transfer performance of the vapor chamber.The main research contents and results are as follows:(1)Preparation of superhydrophobic copper surface.The effects of etching time,Na OH concentration,reaction temperature and modification time on the hydrophobic properties of copper surface were investigated.The influence of etching reaction conditions and modification time conditions on the microstructure and characterization of the contact angle of copper plate surface was intuitively demonstrated by the relationship curves of SEM and reaction conditions-contact angle.The contact angle of the superhydrophobic surface prepared under the optimal reaction conditions is 155.28°.(2)Research on condensation heat transfer performance of different wettability surfaces.By building a visual condensation heat transfer experiment platform,the condensation process of superhydrophilic copper surface,smooth copper plate and superhydrophobic copper surface under different undercooling degrees of supercooling were recorded.The influence of supercooling degrees on the condensation and heat transfer of droplets on superhydrophobic surface was studied by using image processing and analysis technology.The results show that the heat transfer coefficient of superhydrophobic copper surface is significantly higher than that of smooth copper surface and superhydrophilic copper surface,and the heat transfer coefficient of superhydrophobic copper surface is 4.35 times higher than that of smooth copper surface.With the increase of surface subcooling,the nucleation rate of superhydrophobic surface decreases rapidly,the delay of surface renewal rate,and the heat transfer coefficient of superhydrophobic surface decreases gradually.(3)Research on heat transfer performance of new vapor chamber with superhydrophobic surface at the condensation.The superhydrophobic surface was successfully applied to the condensation of the vapor chambers,and the condensation droplets could directly jump from the superhydrophobic surface to the wick of the evaporation by gravity or the combination of droplets,which enhanced the condensation effect.The influence of basic parameters such as the size of the wick at the evaporation of the new vapor chamber,the temperature of different cooling water,the amount of liquid filling rate and the surface wettability of the condensation on the heat transfer performance is explored.The heat transfer efficiency is increased by 1.25 times and 1.786 times,respectively,and the lowest thermal resistance is 0.1464℃/W,compared with the superhydrophilic and smooth vapor chambers with the condensation.It is proved that superhydrophobic surface has high application value in the process of enhancing heat transfer of the vapor chambers.