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Liquid impingement dynamics on superheated superhydrophobic surfaces

过热超疏水表面上的液体冲击动力学

基本信息

批准号：
1707123
负责人：
Julie Crockett
金额：
$ 37.36万
依托单位：
Brigham Young University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1707123&HistoricalAwards=false
关键词：
Liquid impingement dynamics superheated superhydrophobic

项目摘要

Characterizing heat transfer from a solid plate to a liquid is important in multiple applications where cooling, condensation, or cleaning properties are necessary. Superhydrophobic surfaces can be self-cleaning and thus present an immediate advantage for their use when in contact with liquids. Water will sit atop the micro/nano structures, leaving an air gap in between the structures and allowing for water to bead up almost completely into a ball on the surface. The water will then roll from the surface and thus it becomes self-cleaning. Although the liquid dynamics of impingement on a superhydrophobic surface are fairly well known, the understanding of heat transfer from these surfaces with micro-scale air gaps to an impinging liquid is not well characterized. Impinging liquids are able to remove heat by the constant replenishing of new, cooler liquid. This study will explore the capability of impinging water droplets or impinging water jets to remove heat from a superhydrophobic surface while still effectively being self cleaning. Superhydrophobic surfaces are generated by combining microscale structuring and a hydrophobic coating such that liquids are often only in contact with a fraction of the solid surface. Impinging processes are rich in fundamental fluid flow and thermal transport physics and represent an excellent test bed to consider with superhydrophobic surfaces since superhydrophobicity exerts enormous influence on the liquid-solid surface tension, which is dominant in impinging processes. It is expected that thermal transport physics of liquid impingement on superhydrophobic surfaces will experience greater departure from classical behavior than has been observed hydrodynamically. The objectives of this work are to characterize the transport for: 1) impinging droplets (normal and oblique impingement angles), and 2) liquid jet impingement (normal and oblique impingement). The proposed research plan includes coupled experimental and analytical approaches. The processes that will be explored have significance in next generation high efficiency condensers, desalinization processes, self-cleaning surfaces, and easily maintained spray cooling systems.

表征从固体板到液体的热传递在冷却，冷凝或清洁特性是必要的多种应用中是重要的。超疏水表面可以自清洁，因此在与液体接触时具有直接的优势。水将停留在微纳米结构的顶部，在结构之间留下一个气隙，使水几乎完全在表面形成一个球。然后水就会从表面滚出来，这样它就会自我清洁。虽然在超疏水表面上撞击的液体动力学是相当众所周知的，但从这些具有微尺度气隙的表面到撞击液体的热传递的理解并没有很好地表征。碰撞液体能够通过不断补充新的、较冷的液体来消除热量。本研究将探索撞击水滴或撞击水射流从超疏水表面去除热量的能力，同时仍然有效地进行自清洁。超疏水表面是通过结合微尺度结构和疏水涂层产生的，这样液体通常只与固体表面的一小部分接触。撞击过程具有丰富的基本流体流动和热输运物理性质，由于超疏水性对撞击过程中占主导地位的液固表面张力有巨大的影响，因此撞击过程是考虑超疏水表面的一个很好的试验平台。预计液体撞击超疏水表面的热输运物理将经历比流体动力学观察到的更大的偏离经典行为。本工作的目的是表征：1)撞击液滴（正常和斜撞击角）和2)液体射流撞击（正常和斜撞击）的传输特性。提出的研究计划包括实验和分析相结合的方法。将探索的工艺在下一代高效冷凝器、脱盐工艺、自清洁表面和易于维护的喷雾冷却系统中具有重要意义。