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Analysis of Capillary Flow in a Parallel Microchannel-Based Wick Structure with Circular and Noncircular Geometries
Langmuir ( IF 3.7 ) Pub Date : 2020-11-05 , DOI: 10.1021/acs.langmuir.0c02226 Binjian Ma 1
Langmuir ( IF 3.7 ) Pub Date : 2020-11-05 , DOI: 10.1021/acs.langmuir.0c02226 Binjian Ma 1
Affiliation
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Capillary flow in porous media is of great significance to many different applications including microfluidics, chromatography, and passive thermal management. For example, heat pipe has been widely used in the thermal management of electronic system due to its high flexibility and low thermal resistance. However, the critical heat flux of heat pipe is often limited by the maximum capillary-driven liquid transport rate through the wicking material. A significant number of novel porous material with complex structures have been proposed in past studies to provide enhanced capillary-driven flow without substantial reduction in pore size and porosity. However, the increasing level of structural complexity often leads to a more tortuous flow path, which deprives the merits of enhanced capillarity. In this study, we examined the capillary performance of a porous material with simple geometric structures both analytically and numerically. Specifically, the capillary rate of rise of water in parallel hollow microchannels with different cross-sectional shapes is derived by solving the momentum transport equation. The relationships between the capillary flow rate and wicking height are further validated by two-phase flow simulation based on the conservative level-set method. The results demonstrate that parallel microchannel configuration, despite its geometric simplicity, provides superior capillary performance than most existing porous media in terms of both capillary flow rate and ultimate wicking height. In addition, design of noncircular cross section reduces the viscous drag and increases the packing density of the microchannels in the bulk solid without affecting the capillary pumping pressure. These features contribute to a further enhancement in the capillary performance by up to 32%. These results provide important guidance to the rational design of porous material with enhanced fluid transport property in a variety of microfluidic systems.
中文翻译：
具有圆形和非圆形几何形状的基于微通道的平行毛细结构中的毛细管流动分析
多孔介质中的毛细管流动对许多不同的应用具有重要意义，包括微流体，色谱和被动热管理。例如，热管由于其高柔韧性和低热阻而被广泛用于电子系统的热管理。但是，热管的临界热通量通常受到通过芯吸材料的最大毛细管驱动液体传输速率的限制。在过去的研究中，已经提出了大量具有复杂结构的新型多孔材料，以提供增强的毛细管驱动的流动，而不会显着减小孔径和孔隙率。但是，结构复杂性水平的提高通常会导致流动路径更加曲折，从而剥夺了增强毛细管作用的优点。在这个研究中，我们通过分析和数值研究了具有简单几何结构的多孔材料的毛细管性能。具体而言，通过求解动量传递方程，得出具有不同横截面形状的平行中空微通道中水的毛细上升速率。通过基于保守水平集方法的两相流模拟，进一步验证了毛细管流速与芯吸高度之间的关系。结果表明，尽管平行微通道结构几何简单，但在毛细管流速和最终芯吸高度方面都比大多数现有多孔介质提供了卓越的毛细管性能。此外，非圆形横截面的设计减少了粘性阻力并增加了散装固体中微通道的堆积密度，而不会影响毛细管泵送压力。这些特征有助于将毛细管性能进一步提高多达32％。这些结果为在各种微流体系统中提高流体传输性能的多孔材料的合理设计提供了重要的指导。
更新日期：2020-11-17
中文翻译：
具有圆形和非圆形几何形状的基于微通道的平行毛细结构中的毛细管流动分析
多孔介质中的毛细管流动对许多不同的应用具有重要意义，包括微流体，色谱和被动热管理。例如，热管由于其高柔韧性和低热阻而被广泛用于电子系统的热管理。但是，热管的临界热通量通常受到通过芯吸材料的最大毛细管驱动液体传输速率的限制。在过去的研究中，已经提出了大量具有复杂结构的新型多孔材料，以提供增强的毛细管驱动的流动，而不会显着减小孔径和孔隙率。但是，结构复杂性水平的提高通常会导致流动路径更加曲折，从而剥夺了增强毛细管作用的优点。在这个研究中，我们通过分析和数值研究了具有简单几何结构的多孔材料的毛细管性能。具体而言，通过求解动量传递方程，得出具有不同横截面形状的平行中空微通道中水的毛细上升速率。通过基于保守水平集方法的两相流模拟，进一步验证了毛细管流速与芯吸高度之间的关系。结果表明，尽管平行微通道结构几何简单，但在毛细管流速和最终芯吸高度方面都比大多数现有多孔介质提供了卓越的毛细管性能。此外，非圆形横截面的设计减少了粘性阻力并增加了散装固体中微通道的堆积密度，而不会影响毛细管泵送压力。这些特征有助于将毛细管性能进一步提高多达32％。这些结果为在各种微流体系统中提高流体传输性能的多孔材料的合理设计提供了重要的指导。
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