Heat transfer processes in patterned and rough microchannels

图案化和粗糙微通道中的传热过程

• 批准号: 1606192
• 负责人: Prabhakar Bandaru
• 金额: $ 30万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1606192&HistoricalAwards=false
• 关键词: Heat; transfer; processes; patterned; rough

Any practical surface is rough, with the roughness extending over several scales - from the atomic scale to that observable to the naked eye. The proposed work aims to investigate how the influence of such characteristics would modify fluid (liquid or gas) flow. For example, roughness could be related to a hydrophobic aspect, where liquid would skim along the surface at a larger velocity (with less friction and needing less driving force and energy) compared to a smooth surface. For a heated liquid, such larger velocity may imply larger heat transfer. However, the roughness on the surface is also comprised of air of low thermal conductivity, which would be expected to reduce the efficacy of heat transfer. Through such considerations, the amount and rate of heat transfer may be sensitively regulated by controlling the amount of roughness and will be studied, experimentally and theoretically, in this work. The consequent greater understanding obtained would yield fundamental scientific insights into roughness, friction, and the control of heat. It is also aimed to translate such insights to the immediate design of microscale pipes and flows, with applications ranging from the cooling of electronic components and devices to biomedical diagnostics. Longer-term applications to enhancing the efficiency of fluid flow, lubrication, and water filtering, with respect to reducing drag and heat transfer across the interface are being considered. The overarching goal is to gain quantitative understanding of multiphase flow and heat transfer over rough surfaces. The project will investigate the influence of nano- and micro-scale surface effects in modulating measurable macroscale properties such as temperature, pumping power, and heat transfer, with very wide ranging consequences. From an experimental point, the project mainly involves the: (a) development and analysis of patterned/rough superhydrophobic surfaces, and (b) measurement of velocity profiles and effective heat transfer coefficients in such surface constituted channel flow, in concert with theoretical model validation. It is concurrently aimed to develop and implement the theoretical and numerical tools for modeling multiphase flow and heat transfer over ordered and spatiotemporally disordered surfaces. Probabilistic frameworks and stochastic mapping of random flow domains will be used to model the inherent variability of the surfaces and the resulting flows. The research would substantially extend the state of the art in thermal transport modeling involving ordered surfaces to random nanostructured surfaces. The tuning of thermal transport processes, considered through the theoretical and experimental efforts, would enable higher efficiency micro-/nano-fluidics with a wide range of physical, chemical, and biological applications.

任何实际的表面都是粗糙的，粗糙度有好几个尺度--从原子尺度到肉眼可见的尺度。这项拟议的工作旨在调查这些特性的影响将如何改变流体(液体或气体)流动。例如，粗糙度可能与疏水方面有关，与光滑的表面相比，液体将以较大的速度沿表面掠过(摩擦力较小，需要的驱动力和能量较少)。对于加热的液体，这样大的速度可能意味着更大的热传递。然而，表面的粗糙度也由低导热系数的空气组成，这可能会降低换热效率。通过这些考虑，可以通过控制粗糙度来敏感地调节热传递的量和速率，并将在本工作中从实验和理论上进行研究。随之而来的更大的理解将产生对粗糙度、摩擦和热量控制的基本科学见解。它还旨在将这些见解转化为微型管道和流动的即时设计，应用范围从电子元件和设备的冷却到生物医学诊断。在减少界面上的阻力和热传递方面，正在考虑提高流体流动、润滑和水过滤的效率的长期应用。其首要目标是对粗糙表面上的多相流和热传递进行定量的了解。该项目将研究纳米和微米尺度表面效应对调节可测量的宏观特性的影响，如温度、泵浦功率和热传递，结果非常广泛。从实验的角度来看，该项目主要包括：(A)开发和分析图案化/粗糙的超疏水表面，以及(B)测量构成槽道流动的这种表面的速度分布和有效换热系数，并与理论模型验证相一致。同时开发和实现了用于模拟有序和时空无序表面上的多相流动和换热的理论和数值工具。随机流域的概率框架和随机映射将被用来模拟表面和所产生的流动的内在可变性。这项研究将极大地将涉及有序表面的热传输建模的技术水平扩展到随机纳米结构表面。通过理论和实验的努力，对热传递过程进行调整，将使微/纳米流体具有更高的效率，具有广泛的物理、化学和生物应用。