Research Of Wick Structure Based On The Plant Stoma And Leaf Vein Structure

Miniaturization and high integration of electronic products needs good heat dissipation. It is important to increase the heat dissipation effect without the volume increasing of heat-sink device. What’s more, temperature uniformity is a key for designing the cooling equipment. As a cooling equipment, vapor chamber can increase the heat transfer efficiency, because the heat exchange happens in the two dimensional surface. Due to the phenomenon of heat and mass transfer occurring in plants, special structures of the branches and the leaves are developed. The stomas and veins help transporting fluids and transferring heat as efficient as possible, therefore, to design a new vapor chamber, it is great help to study those structures. In this paper, the fluid mechanism and thermal transmission of leaf stoma and vein system of heat tolerant plants are studied. The substomatal cavity structure is used in design of the wick microstructure, and the leaf vein system is applied to the whole wick structure. High permeability and capillary force can be achieved from the new structure. In other words, the thermal resistance of the new wick structure is lower than normal one. A new wick structure used in the evaporation of the vapor chamber is researched.Firstly, the real parameters of the stoma and vein were measured for the next work. Based on the Fick’s law and equation of mass conservation, substomatal cavity structures were calculated. The results could be used to evaluate some common shapes of the cavity. Then the structure with better performance was applied to the wick microstructure by calculating and analyzing its heat transfer. The analysis of the microstructure was established with the equivalent circuit method. The numerical models of leaf vein system were also established based on the real parameters such as the width, slope, bifurcation angle and flow velocity. The influence on heat transfer about the symmetry, parallelity and bifurcation angle of the leaf vein was analyzed by the numerical models.Finally, the experiment was made to simulate the real working condition of the vapor chamber with the new wick structure manufactured by chemical corrosion. By comparing the results of the structure under different external conditions, the difference of bifurcation angle working on the whole thermal resistance of the wick structure was also discussed.