Numerical Analysis And Design Of Multi-wick-column Vapor Chamber Structure

The critical thermal management problem in photoelectric field is the uniform tempera-ture distribution of concentrated heat sources and vapor chamber is an effective solution. Va-por chamber is a device of phase-change heat transfer. The structure and heat source distribu-tion are significant factors which lead to performance difference of a vapor chamber. Takingthe heat source distribution, the wick column diameter and distribution as breaches, the fol-lowing researches have been carried out in this dissertation:(1) The heat and mass transfer mathematic model of vapor chamber was established, theboundary conditions of flow and heat transfer of the vapor chamber were determined and thenumerical solving technique was demonstrated. The reliability of the proposed model was al-so validated.(2) The relation between the performance of vapor chamber and multi-heat-source spac-ing was obtained. An experimental device was set up to measure the temperature distributionof vapor chamber under different spacing between separated heat sources, the experimentalresults were compared with the numerical conclusions. The results show that the concentratedheat sources under low-heat-flux condition can make vapor chamber perform better in heattransfer while ought to be separated, under high-heat-flux condition, to avoid “dry-out” ofvapor chamber.(3) The relation between the thermal and hydraulic performance of vapor chamber andthe wick column diameter was obtained. The results predict that wick column provides anauxiliary return path for the working liquid and the capillary limit of vapor chamber is in-creased. The comparatively low thermal conductivity of wick column yet gives rise to thethermal resistance of vapor chamber. A smaller diameter of wick column turns out to be bet-ter.(4) A vapor chamber with composite-structured wick column was simulated and the re-sults predict that the composite-structured wick column, compared with the sintered wickcolumn, has the comprehensive advantages of decreasing thermal resistance and increasingcapillary limit of vapor chamber (5) The relation between the temperature distribution, flow distribution and thermal per-formance of vapor chamber and multi-column spacing was obtained. The results demonstratethat the capillary limit of vapor chamber is further increased by the multi-column. Columnswhich are close to the heat source affect the performance of vapor chamber more significantly.The comparatively larger separation distance makes the vapor chamber perform better. It isfavorable to improve the performance of vapor chamber by placing wick column near the heatsource.