Research On Heat Transfer Characteristics And Optimization Design Of Vapor Chamber Hot Plate

Heat pipe is a high-efficiency heat exchange device in which the liquid working fluid undergoes evaporative condensation phase change in the internal space.This paper studies the phase change heat transfer and flow state of the working fluid inside the vapor chamber hot plate,using numerical simulation methods.The main research contents include the following aspects:The two dimension calculation model of the vapor chamber hot plate heat transfer is constructed firstly,including mathematical simulation,geometric model and phase change model,so as to obtain the distribution of the velocity field and temperature field in the vapor chamber hot plate.The simulation results were compared with the existing research results to verify the accuracy and reliability of the model.When the hot plate is started,the temperature of the evaporation section increases continuously,and bubbles are gradually generated on the heated wall surface.After the bubbles are generated,they move upward and at the same time break and aggregate,so the bubbles in the liquid pool have different sizes and shapes.Last part of the bubbles break off the surface of the liquid pool and move upward.On the surface of the condensing section,the vapor condenses into liquid,and the liquid film moves downward under the action of gravity and finally replenishes the liquid pool.Secondly,the local part of the model was improved.The influence of the incline angle,liquid filling rate,working medium,surface wettability,heating power and vacuum degree on the phase transformation thermal process of the vapor chamber hot plate was investigated.Explore the change of thermal conductivity of the vapor chamber hot plate under different conditions.The results show that the greater the inclination angle,the stronger the heat transfer capacity.Proper liquid filling ratio can effectively improve the heat transfer capacity of the hot plate.When water is the working medium,the heat transfer capacity of the hot plate is greater than that of acetone and greater than that of R134 a.Improving the wettability of the evaporative and condensing wall surfaces has different effects on the heat transfer capacity of the hot plate.Finally,taking the three-dimensional vapor chamber hot plate as the research object,the phase change of the internal working medium of the hot plate in the process of heat transfer is studied.The changes of volume fraction of each phase,temperature of working medium and velocity of working medium in three dimensional vapor chamber hot plate are obtained.By changing the channel structure and channel width-to-height ratio,the numerical simulation and optimization design of vapor chamber hot plate with different channel structure were carried out.Comparing the temperature uniformity,thermal resistance,and convection heat transfer coefficient between the circular heat pipe and the flat-plate hot plate,it is concluded that the flat-plate hot plate has the advantages of good temperature uniformity,low thermal resistance,and strong heat transfer capacity.On this basis,the human capillary structure is bionic,the groove structure of vapor chamber hot plate is improved,and a kind of micro-grooved plate structure with high efficiency heat transfer is designed.