Study On Heat Transfer Performance Of Discontinuous Channel-type Flat Heat Pipes

With the rapid development of electronic technology products,electronic components show a development trend of high integration,high frequency and small volume,which brings the increase of power consumption and calorific value of electronic components.Because of its good heat transfer performance,small size,and close fitting with the heating device,flat heat pipe has become the first choice of modern electronic products to solve the problem of heat dissipation.However,the heat transfer performance of flat heat pipe decreases with the increase of heat source temperature,so how to improve the heat transfer performance limit of flat heat pipe has important research significance.To this,in this paper,the flat heat pipe work in internal heat and mass transfer process was analyzed,and put forward to improve the steam transmission and working medium return rate to improve the heat transfer performance of plate heat pipe's point of view,we design a copper-discontinuous water trough type plate heat pipe,through the numerical simulation method for the flat heat pipe structure optimization design,set up the experimental test platform,The heat transfer performance of the same specifications of continuous groove flat heat pipe was compared.The main research contents and conclusions of this paper are as follows:First,the basic principle of flat heat pipe work and several factors affecting the heat transfer performance of flat heat pipe are discussed.According to the principle,the methods to improve the heat transfer performance of flat heat pipe are put forward: to increase the evaporation rate and condensation rate of working medium,to accelerate the steam transmission and working medium reflux rate.The grid diagram of internal heat resistance of flat heat pipe during heat transfer is analyzed,and a viewpoint is put forward that the heat transfer performance of flat heat pipe can be improved by changing the continuity of groove to accelerate the steam transmission and the rate of working medium return.A discontinuous groove type flat heat pipe is designed.Secondly,the internal structure of the discontinuous channel heat pipe was numerically simulated by using the finite element simulation software Fluent,and the influences of channel shape,working medium type(water,ethanol),length-to-width ratio on the capillary force and radial heat transfer were simulated.The simulation results show that the capillary force and radial heat transfer capacity are the strongest when the working medium is water in the rectangular channel with an aspect ratio of 2:1.Thirdly,referring to the phenomenon of plant vein branching in nature,the vein branching structure is added inside the flat heat pipe to make the channel change from continuous type to discontinuous type.First branch calculated through theory of structural physical parameters on the size of the internal flow resistance,the influence of selecting the best branch series and size,then adopt the method of numerical simulation,the six different veins branching Angle to simulate the flow velocity.The simulation results show that when the branching Angle is 45°,the velocity in the tube increases the most.Fourthly,two kinds of discontinuous channel type flat heat pipes with different vein branches and the same specifications of continuous channel type flat heat pipes were designed and processed for experimental test.The results showed that:Two non continuous groove of flat heat pipe heat transfer performance is better than the continuous groove whole flat heat pipe,and both the continuous groove road flat heat pipe are in the liquid rate was 40% when the optimum,the heat transfer performance of different to a higher branch to branch contrast flat heat pipe under high temperature,the heat transfer performance is more stable,and in the Angle of 60 °,the heat transfer performance can be further improved.The view that changing groove continuity can improve the heat transfer performance of flat heat pipe is verified.