Simultaneous prediction of dryout heat flux and local temperature for thin film evaporation in micropillar wicks
Simultaneous prediction of dryout heat flux and local temperature for thin film evaporation in micropillar wicks
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DOI：
10.1016/j.ijheatmasstransfer.2019.02.074
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发表时间：
2019-06-01
影响因子：
5.2
通讯作者：
Wang, Evelyn N.
中科院分区：
文献类型：
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作者：
Vaartstra, Geoffrey;Lu, Zhengmao;Wang, Evelyn N.
多孔芯在热管理中具有很大的兴趣，因为它们能够被动地为薄膜蒸发提供液体，这是一种在高性能电子设备中可靠地散热的有前途的方法。虽然干燥热通量已被很好地表征为许多芯配置，关键的设计信息是缺失的，因为许多以前的模型不能确定蒸发器表面温度的分布。温度梯度是被动毛细泵送机制所固有的，因为液体/蒸汽界面的形状是局部液体压力的函数，导致渗透率和传热系数（HTC）的空间变化。在这里，我们提出了一个全面的建模框架，薄膜蒸发微柱芯，可以预测干涸的热通量和局部温度同时。我们的数值方法捕获的影响，不同的界面曲率的微柱蒸发器，以确定温度和热通量的空间分布。通过结合参数研究，将几何形状和界面形状与局部渗透率和HTC相关联，以计算高效的方式耦合毛细芯中的传热和毛细流动。该模型预测的显着变化的HTC（类似于30%）的微柱芯，突出界面曲率的显着影响。此外，我们能够量化的权衡与提高干燥热通量或HTC通过优化几何形状。我们的模型提供了所有需要的信息，以指导设计和优化的微柱芯解决蒸发器的温度分布，除了干燥热通量。(C)2019由Elsevier Ltd.出版
Porous wicks are of great interest in thermal management because they are capable of passively supplying liquid for thin film evaporation, a promising method to reliably dissipate heat in high performance electronics. While dryout heat flux has been well-characterized for many wick configurations, key design information is missing as many previous models cannot determine the distribution of evaporator surface temperature. Temperature gradients are inherent to the passive capillary pumping mechanism since the shape of the liquid/vapor interface is a function of the local liquid pressure, causing spatial variation of permeability and heat transfer coefficient (HTC). Here, we present a comprehensive modeling framework for thin film evaporation in micropillar wicks that can predict dryout heat flux and local temperature simultaneously. Our numerical approach captures the effect of varying interfacial curvature across the micropillar evaporator to determine the spatial distributions of temperature and heat flux. Heat transfer and capillary flow in the wick are coupled in a computationally efficient manner via incorporation of parametric studies to relate geometry and interface shape to local permeability and HTC. This model predicts notable variations of HTC (similar to 30%) across the micropillar wick, highlighting the significant effects of interfacial curvature. Further, we are able to quantify the tradeoff associated with enhancing either dry out heat flux or HTC by optimizing geometry. Our model provides all of the information needed to guide the design and optimization of micropillar wicks by resolving evaporator temperature distributions in addition to dryout heat flux. (C) 2019 Published by Elsevier Ltd.