EAGER: Innovative 3-D, multiscale flow-boiling wick

EAGER：创新的 3-D、多尺度流动沸腾芯

• 批准号: 1623572
• 负责人: Massoud Kaviany
• 金额: $ 4.94万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 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: 2016-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1623572&HistoricalAwards=false
• 关键词: EAGER; Innovative; multiscale; flow; boiling

Many thermal systems rely on passive (capillary) or active (pumping) liquid supply to evaporation surfaces. Adjacent to evaporation surface, liquid supply and vapor removal have to compete (e.g., pool and flow boiling) unless they are separated with capillary bodies holding the liquid (wetting phase) and vapor. Efficient heat transfer under large local heat flux continues to demand innovative and transformative surface enhancement designs, and one venue has been use of capillary bodies to control distribution of phases adjacent to the evaporation surface. While the capillarity provides the suction for the liquid supply to the surface, there are various liquid and vapor choking limits to consider, so this is a fundamental thermal-hydraulic problem with important applications. A new three-dimensional, multilength scale, distributed evaporation wick is proposed for heat sink capable to removing 1000 W/cm2 with saturated liquid, and this will be a record. It is proposed to create and make available on Internet, illustrative thermal-hydraulics of the capillary bodies, such as the canopy wick (CW). The results of this project on theoretical optimization of CW will advance the thermal management of high-flux sources and will be used in a collaboration with industry which will fabricate and test a heat-sink prototype at high heat fluxes representative of those found in high-power laser applications. The industry collaboration allows for industrial interactions for the University of Michigan students.In saturated, flow boiling the local thermal resistance depends on the local phase distributions, gravity direction, and two-phase flow instabilities. A unique wick structure is proposed to control the liquid delivery, vapor removal, and heat transfer making this resistance independent of the location (distance from the leading edge, or local vapor quality) and gravity, and reducing it to less than 0.05 K/(W/cm2) (i.e., heat transfer coefficient lager than 2x105 W/m2-K), and increase the dryout limit [critical heat flux (CHF)] to larger than 1000 W/cm2. This multidimensional capillary structure, called the canopy wick (CW) aims at separating and controlling the liquid and vapor flow paths based on the integrated evaporation and vapor-escape structures. The CW divides the liquid delivery and liquid spreading-evaporation functions and is an evolution of the modulated wicks previously developed by PI and Advanced Cooling Technologies (ACT) Inc. for passive systems (pool boiling and vapor chambers). The CW provides liquid to a thin evaporation wick (sintered particle monolayer, where the receding meniscus and local thermal nonequilibrium allow for low thermal resistance) covering the heated surface, delays surface dryout (increasing CHF) through high-permeability liquid-directing multiple artery (posts) wick, and creates vapor space and venting with perforated screenlayer roof. The screen-roof perforation opening and pitch are selected to create vapor flow inertial or delayed formation of vapor blanket in the otherwise liquid boundary-layer flow over it. In the proposed experiment, the CW will be constructed from sintered micrometer copper particles (larger particles for posts compared to monolayer) and perforated copper screenlayer (few layers of wire screen), and tested under water flow boiling with one-side heating (large cross-section area channel). The cascading capillary pressure (liquid pressure) in the three porous bodies is carefully matched by pore-size selection to ensure uninterrupted liquid flow. The post height and pitch are of the order of millimeter, the vapor preformation pitch may be larger than the posts to control the exiting vapor momentum, and the channel will have a hydraulic diameter of the order of centimeter.

许多热系统依靠被动（毛细管）或活性（泵送）液体供应来蒸发表面。除非将液体（润湿阶段）和蒸气的毛细管分离，否则在蒸发表面，液体供应和蒸气去除（例如，池和流量沸腾）的毗邻。在大型局部热通量下的有效传热继续需要创新和变革性的表面增强设计，并且一个场所是使用毛细管来控制与蒸发表面相邻的相位的分布。虽然毛细血管为表面液体供应提供了吸力，但要考虑的液体和蒸气窒息极限各种，因此这是重要应用的基本热液压问题。 提出了一种新的三维，多长度刻度，分布式蒸发灯芯是针对能够用饱和液体去除1000 W/cm2的散热器，这将是记录。有人建议在互联网上创建和提供毛细管体的插图式热液，例如Canopy Wick（CW）。该项目对CW的理论优化的结果将推进高通量来源的热管理，并将用于与行业合作，该行业将在高功率激光应用中的高热量中制造和测试一个高热量通量。该行业合作允许密歇根大学学生进行工业互动。在饱和，流动沸腾的当地热阻力取决于当地相位分布，重力方向和两相流动不稳定性。提出了一种独特的灯芯结构，以控制液体输送，清除蒸气和热传递，从而使这种阻力与位置（距离前沿距离或局部蒸气质量）和重力无关，并将其降低到小于0.05 k/（w/cm2）（即比2x105 W/M2-K）较大的限制（即更大的限制），并增加[即增加了较大的热量（即限制）。 w/cm2。这种称为Canopy Wick（CW）的多维毛细管结构旨在基于集成的蒸发和蒸气 - 埃斯卡普结构分离和控制液体和蒸气流道。 CW将液体输送和液体扩散蒸发函数划分，并且是PI和先进冷却技术（ACT）Inc.先前开发的被动系统（池沸腾和蒸气室）的调制灯芯的演变。 CW为较薄的蒸发芯提供液体（烧结的粒子单层，在那里，均匀的半月板和局部热量非平衡允许覆盖加热表面的较低的热耐药性），延迟了表面干燥（增加CHF（增加CHF），通过高渗透性液体液体液体液体导向型多个型动脉（柱子），并创建vapor vapor wick，并带有型号的露天范围，并使用完美的屋顶进行了脚步屋顶。选择了屏幕屋顶穿孔开口和俯仰，以创建蒸气流量惯性或延迟形成的蒸气毯，否则在其上方的液体边界层流中。在拟议的实验中，CW将由烧结的微米铜颗粒（与单层相比较大的柱子颗粒）和穿孔的铜丝线层（较大的铜丝带层）（几层电线筛网），并在水流沸腾的情况下用一侧加热（大横截面区域通道）进行测试。三个多孔物体中的级联毛细管压力（液压）通过孔径选择仔细匹配，以确保不间断的液体流动。柱高度和音高是毫米的顺序，蒸气预制音高可能大于控制退出的蒸气动量的柱子，并且该通道的液压直径将以厘米为单位。