Ultra-thin flat heat pipes (UFHPs) are being explored as a potential thermal management solution to address the heat dissipation challenges of electronic devices. However, the ultra-thin process increases fluid flow resistance and reduces the heat transfer capacity, posing challenges for wick structure optimization. In this study, the effects of wick structure, vapor space, and fluid flow properties on the maximum heat transfer capacity are analyzed by a fluid flow model. Microgroove and microcolumn as wick structures are optimized, and the coupling effects between capillary pressure and fluid flow resistances are analyzed. The maximum heat transfer capacity and the corresponding optimal wick structure dimensions are determined by the vapor space friction and wick structure friction, which are calculated by structural friction coefficients ( and ) and fluid friction coefficients ( and ). The models of fluid flow friction chosen in previous literature are validated for accuracy by Fluent. When the height of the wick structure () or vapor space () increases, the optimal dimensionless wick structure height () increases and decreases under a fixed porosity (), respectively. The optimal of microgroove decreases and that of microcolumn increases as the dimensionless spacing () increases. When ethanol is used as the working fluid, the optimal of microgroove is 1.98 and the optimal of microcolumn is 0.48, under the condition of = 0.3 mm, = 0.15 mm, and = 0.5. This model also emphasizes the importance of working fluid properties on the design of the wick structure, and a higher value of / results in a lower optimal . Moreover, methanol and acetone exhibit higher heat transfer capacity compared with ethanol. This study aims to provide comprehensive design principles for optimizing UFHP heat transfer capacity.

中文翻译：

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超薄扁平热管微槽微柱传热能力优化设计


人们正在探索超薄扁平热管（UFHP）作为一种潜在的热管理解决方案，以解决电子设备的散热挑战。然而，超薄工艺增加了流体流动阻力并降低了传热能力，给毛细结构优化带来了挑战。在本研究中，通过流体流动模型分析了吸液芯结构、蒸汽空间和流体流动特性对最大传热能力的影响。对微槽和微柱作为毛细结构进行了优化，并分析了毛细管压力和流体流动阻力之间的耦合效应。最大传热能力和相应的最佳毛细结构尺寸由蒸汽空间摩擦力和毛细结构摩擦力决定，它们通过结构摩擦系数 ( 和 ) 和流体摩擦系数 ( 和 ) 计算。 Fluent 验证了先前文献中选择的流体流动摩擦模型的准确性。当毛细结构（）或蒸汽空间（）的高度（）增加时，在固定孔隙率（）下，最佳无量纲毛细结构高度（）分别增加和减少。随着无量纲间距()的增大，微槽的最优值减小，微柱的最优值增大。当使用乙醇作为工作液时，在=0.3mm、=0.15mm、=0.5条件下，微槽最佳值为1.98，微柱最佳值为0.48。该模型还强调了工作流体特性对吸芯结构设计的重要性，较高的 / 值会导致较低的最优值。此外，与乙醇相比，甲醇和丙酮表现出更高的传热能力。 本研究旨在为优化超滤高压传热能力提供全面的设计原则。