Capillary and Boiling Limits of Micropillared Thermal Wicks

微柱热芯的毛细管和沸腾极限

• 批准号: 1134104
• 负责人: Carlos Hidrovo Chavez
• 金额: $ 30万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1134104&HistoricalAwards=false
• 关键词: Capillary; Boiling; Limits; Micropillared; Thermal

PI: Carlos HidrovoProposal #: 1134104This project aims to understand the governing physics behind capillary limit flow in microstructures with phase change, with the objective of developing thermal wicks capable of dissipating upwards of 1 kW/cm2. The transformative aspect of the project resides in providing new insights into the effects that microstructure geometry has on thermal-phase change capillary flow systems. Furthermore, this understanding will lead to the development of novel wicking structures based on vertical micropillared arrays for heat pipe and vapor chamber applications capable of low temperature heat fluxes not seen before.Specifically, the project will tackle and elucidate the governing physics behind the capillary flow within arrays of vertically etched silicon micropillars, particularly related to phase change heat transfer applications. The following questions will be addressed by the project: (1) How does microstructure affect capillary flow? (2) What are the key parameters that control capillary pumping capabilities in such wicking structures? (3) How are heat transfer and phase change processes coupled to the capillary flow? (4) Can MEMS technology, in the form of micropillared wicks, be implemented as a means of exceeding current heat pipe and vapor chamber heat flux dissipation capabilities? In order to answer these questions, the following specific tasks have been identified: (i) Introduction of a novel experimental setup capable of simultaneously obtaining thermal and capillary flow data for different wick samples. This system will be used to assess the thermo-hydraulic performance of silicon based micropillar samples. (ii) Fabrication of silicon based micropillared wicks, with precisely controlled microstructure of varying geometry. (iii) The experimental results will be complemented by and validated against compact models that will capture the relevant physics associated with the capillary flow, phase change (boiling), and thermal transport in these systems. (iv) The coupled experimental and modeling results will be used as a design tool towards optimization of ideal microstructure geometries for the silicon micropillar array samples.The intellectual merit of the project includes elucidating the impact that micro-geometry have on phase change capillary systems. Since both the models developed and the experiments conducted will be done on specially designed samples with known geometry, the underlying physics will have a much clearer context. This will allow for better understanding of the key parameters that affect capillary flow in thermal systems with phase change. Lessons learned from this research will carry over to the understanding of capillary flow with phase change on non-regular and non-uniform structures, such as fractals.The broader impact of the project includes having significant relevance in the general area of capillary flow in porous media, with major implications for fields such as geology, hydrology and manufacturing. The problems to be tackled here present rich engineering, physics, and materials challenges, great cross-disciplinary projects for the graduate and undergraduate students involved. The PI is a young leader in experimental thermal fluids, MEMS and optical diagnostics. The results of the project will provide new classroom materials for courses that the PI teach or is currently developing, as well as outreach activities geared towards elementary school audiences. Importantly, the PI will initiate an undergraduate summer internship program, aimed at underrepresented UT freshmen and sophomores to truly prepare them as multidisciplinary leaders of future engineering challenges.

PI：Carlos Hidrovopososal＃：1134104该项目旨在了解随着相变的微观结构中毛细管极限流的治疗物理，目的是开发能够耗散1 kW/cm2的热芯。该项目的变革性方面涉及对微观结构几何对热相变毛细管流系统的影响的新见解。此外，这种理解将导致基于垂直的微孔阵列的新颖芯片结构的发展，用于热管和蒸气室应用，能够以前看不见的低温热通量。具体来说，该项目将处理并阐明在端状蚀刻的Silicon Micropillars阵列内的毛细管流动量，特别是相关的相关速度转移，尤其是相关的相关速度变化。该项目将解决以下问题：（1）微观结构如何影响毛细管流？ （2）控制此类芯片结构中毛细管抽水功能的关键参数是什么？ （3）如何与毛细血管流相结合？ （4）MEMS技术以微孔芯的形式可以作为超过当前的热管和蒸气室热通量耗散功能的一种手段吗？为了回答这些问题，已经确定了以下特定任务：（i）引入一个新型的实验设置，能够同时获得不同灯芯样品的热和毛细血管流数据。该系统将用于评估基于硅的微柱样品的热功能性能。 （ii）制造基于硅的微芯片灯芯，具有不同几何形状的精确控制的微观结构。 （iii）实验结果将通过紧凑的模型进行补充并验证，这些模型将捕获与毛细管流，相变（沸腾）和这些系统中的热传输相关的相关物理。 （iv）耦合实验和建模结果将用作设计工具，以优化对硅微只阵列样品的理想微观结构几何形状。该项目的智力优点包括阐明微观的影响对相变毛细管系统的影响。由于开发的模型和进行的实验都将在具有已知几何形状的特殊设计的样品上进行，因此基础物理学将具有更清晰的背景。这将使您可以更好地了解随着相变的热系统影响毛细血管流的关键参数。从这项研究中学到的经验教训将继续理解毛细血管流，随着分形等不规则和不均匀结构的相变，该项目的更广泛影响包括在多孔介质的一般毛细血管流中具有显着相关性，对诸如地质，水文和制造等领域的主要影响。在这里要解决的问题提出了丰富的工程，物理和材料挑战，这是研究生和本科生的跨学科项目。 PI是实验热流体，MEM和光学诊断的年轻领导者。该项目的结果将为PI教授或正在开发的课程提供新的课堂材料，以及针对小学观众的外展活动。重要的是，PI将启动一项本科暑期实习计划，旨在以代表性不足的UT新生和大二学生真正做好准备作为未来工程挑战的多学科领导者的准备。