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.

主要研究者：卡洛斯Hidrovo提案编号：1134104该项目旨在了解相变微结构中毛细极限流动背后的控制物理学，目的是开发能够耗散1 kW/cm 2以上的热芯。该项目的变革方面在于提供新的见解，微观结构的几何形状对热相变毛细流动系统的影响。此外，这种理解将导致开发基于垂直微柱阵列的新型芯吸结构，用于热管和蒸汽室应用，能够实现以前从未见过的低温热通量。具体来说，该项目将解决并阐明垂直蚀刻硅微柱阵列内毛细流动背后的主导物理学，特别是与相变传热应用相关的物理学。本计画将探讨下列问题：（1）微结构如何影响毛管流？(2)在这种芯吸结构中，控制毛细泵送能力的关键参数是什么？(3)传热和相变过程如何与毛细流动耦合？(4)微柱芯形式的MEMS技术能否作为一种超越当前热管和蒸汽室热通量耗散能力的手段来实现？为了回答这些问题，已经确定了以下具体任务：（i）引入一种新的实验装置，能够同时获得不同芯样品的热和毛细流动数据。该系统将用于评估硅基微柱样品的热工水力性能。(ii)硅基微柱芯的制造，具有精确控制的不同几何形状的微结构。(iii)实验结果将得到补充，并验证对紧凑的模型，将捕捉相关的物理与毛细流动，相变（沸腾），并在这些系统中的热传输。(iv)耦合的实验和建模结果将被用来作为一种设计工具，对理想的微结构的几何形状的优化硅微柱阵列samples.The智力价值的项目，包括阐明的影响，微几何形状的相变毛细管系统。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别设计的样品上进行，因此基础物理学将具有更清晰的背景。这将有助于更好地了解影响相变热系统中毛细流动的关键参数。从这项研究中吸取的经验教训将延续到对非规则和非均匀结构（如分形）上相变毛细流动的理解。该项目的更广泛影响包括在多孔介质中毛细流动的一般领域具有重要意义，对地质学，水文学和制造业等领域具有重大意义。这里要解决的问题目前丰富的工程，物理和材料的挑战，伟大的跨学科项目的研究生和本科生参与。PI是实验热流体、MEMS和光学诊断领域的年轻领导者。该项目的成果将为PI教授的课程或目前正在开发的课程提供新的课堂材料，以及面向小学受众的推广活动。重要的是，PI将启动一个本科生暑期实习计划，针对代表性不足的UT新生和大学生，真正让他们成为未来工程挑战的多学科领导者。