The Influence Of Different Microstructures On The Heat Transfer Performance Of The Evaporating Section Of Separate Heat Pipe

As the heat flux of electronic components is getting higher and higher,the heat dissipation of electronic components is attracting more and more attention.However,the heat dissipation potential of traditional heat sinks is limited by space,which makes it difficult to meet the cooling demand of electronic components with high power consumption in small space.The separate heat pipe,as a kind of high efficient heat transfer device with many excellent heat transfer characteristics,has been widely researched in the field of communication base station,aerospace and other large and medium-sized equipment.It has great advantages and potential in the application of electronic radiator.Thus it's necessary to research micro and miniature separate heat pipe applied to cooling system in narrow space.In this paper,the wickless structures of the dendritic bionic microchannel and parallel microchannel are applied to the evaporation section of the separate heat pipe.Experimental research is carried out on the two kinds of microchannel separate heat pipes,and three-dimensional numerical simulation is conducted on the dendritic bionic microchannel.The main work is as follows:Firstly,experiment platform was established.For the same constant heating power under the condition of different filling rates,the start-up and operation state characteristics of the parallel microchannel separate heat pipe and the dendritic bionic microchannel separate heat pipe were experimentally studied.The results found that under the given four filling rate,the two kinds of microchannel separate heat pipe can start up and keep stable operations.And compared to the parallel microchannel separate heat pipe,the start-up time,start temperature and the evaporation temperature of the dendritic bionic microchannel separate heat pipe are lower under the corresponding filling rate.Secondly,the thermal resistance characteristic of the parallel microchannel separate heat pipe and dendritic bionic microchannel heat pipe were experimentally researched under variable heating power.The results show that the thermal resistances of the dendritic bionic microchannel separate heat pipe change with the heating power in the same trend with that of parallel microchannel separate heat pipe,but the thermal resistances of the former are slightly lower than that of the latter.Finally,the dendritic bionic microchannel is further studied through three-dimensional numerical simulation,and the temperature and pressure distribution characteristics of the horizontally placed microchannel are analyzed and compared with the temperature and pressure distribution of the vertically placed microchannel.In addition,the heat transfer characteristics of the dendritic biomimetic microchannel with different depth-to-width ratios and with different Reynolds numbers were discussed.The simulation results show that the temperature distribution of the horizontally placed dendritic biomimetic microchannel is not different from that of the vertically placed microchannel,but the pressure distribution is completely different.The depth-to-width ratio of the dendritic bionic microchannel has a certain influence on its average heat transfer coefficient.The average pressure drop at the entrance and exit of the dendritic bionic microchannel with the same depth-to-width ratio increased as the Reynolds number increased,but the augment was not large.The average heat transfer coefficient of the dendritic bionic microchannel decreased with the increase of the Reynolds number.And the Reynolds number has different influences on the heat transfer performance of the dendritic bionic microchannel at different depth-to-width ratios.