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首页> 外文期刊>International Journal of Heat and Mass Transfer >Biomimetic Structures by Leaf Vein Growth Mechanism for Pool Boiling Heat Transfer Enhancements
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Biomimetic Structures by Leaf Vein Growth Mechanism for Pool Boiling Heat Transfer Enhancements

机译：叶静脉生长机制的仿生结构池沸腾热传递增强

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Novel biomimetic structures are designed and synthesized to enable liquid water flowing from the periphery to the center of a heating surface, and promote local liquid wicking and active nucleation site density, which enhance the critical heat flux (CHF) and heat transfer coefficient (HTC) of pool boiling heat transfer. The biomimetic structures are designed by mimicking leaf vein growth from an initial point of petiole to an architecture that supplies water and nutrition to the whole leaf lamina. The in-plane flow channels are developed to distribute liquid toward bubble nucleation sites on a heating surface. The in-plane flow channels are then fabricated by: 1) machining a solid biomimetic groove structure at 250 μm height on plain copper surfaces, 2) depositing ～70 nm diameter copper nanowires (CuNWs) of height 25 μm on the solid biomimetic groove structure, and 3) sintering ～25 μm diameter copper powder to create porous biomimetic structures at various heights. The experimental pool boiling results on different structures show that the sintered porous biomimetic structure at 1.0 mm height yields the highest CHF of 343.1 W/cm~2, an increase of 206% over that on a polished plain copper surface, which is due to the biomimetic channels providing easier access of liquid water flow toward the dry-out spots as indicated by a liquid inflow factor. The biomimetic structure of CuNWs has dramatically increased CHF and heat transfer coefficient (HTC) than that of a plain surface and a solid biomimetic structure. A theoretical analysis of the liquid thin film beneath hovering bubbles reveals that the population density of vapor stems in the liquid thin film increases with a decrease of the vapor stem diameter as heat flux increases. Moreover, the porous biomimetic structures take advantage of active nucleation sites and their wicking effect to delay the hydrodynamic instability of the liquid thin film, thus increasing the pool boiling heat transfer.
机译：设计和合成的新型仿生结构，以使液体水从周边流动到加热表面的中心，并促进局部液体芯吸和活性成核位点密度，增强临界热通量（CHF）和传热系数（HTC）池沸腾热传递。仿生结构是通过从叶柄的初始点模拟叶静脉生长来设计为将水和营养的架构中的架构进行设计。开发平面内流动通道以将液体分布在加热表面上的气泡成核位置。然后通过以下方式制造平面流动通道：1）在普通铜表面上以250μm高度加工固体仿生槽结构，2）在固体仿生槽结构上沉积高度25μm的〜70nm直径的铜纳米线（CUNW） 3）烧结〜25μm直径铜粉，以在各种高度上产生多孔仿生结构。在不同的结构上沸腾的实验池沸腾表明，烧结多孔仿生结构在1.0 mm高度，最高CHF为343.1W / cm〜2，比抛光普通铜表面增加206％，这是由于如液体流入因子所示，仿生通道提供更容易进入液体水流向干燥斑点。 CUNW的仿真结构显着增加了CHF和传热系数（HTC），而不是平面表面和固体仿生结构。悬停气泡下方的液体薄膜的理论分析表明，随着热通量增加，液体薄膜中的蒸气茎的群体密度增加随着热通量增加而增加。此外，多孔仿生结构利用活性成核位点及其芯吸效应，以延迟液体薄膜的流体动力不稳定性，从而增加池沸腾热传递。

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