Adaptive Hotspot Cooling with Self-Propelled Jumping Condensate

采用自驱动跳跃式凝结水的自适应热点冷却

• 批准号: 1236373
• 负责人: Chuan-Hua Chen
• 金额: $ 25万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236373&HistoricalAwards=false
• 关键词: Adaptive; Hotspot; Cooling; Self; Propelled

CBET-1236373Chuan-Hua ChenDuke UniversityMobile hotspots are prevalent in electronic systems, including microprocessors and power electronics with constantly changing computing tasks and external payloads. Existing cooling solutions are generally designed for fixed hotspots (e.g. thermoelectric coolers) or slowly varying heat loads (e.g. flat plate heat pipes), and are therefore not adequate to address the cooling challenges of moving hotspots. This study aims at developing a novel phase-change cooling mechanism for adaptive thermal management of hotspots, where the self-propelled jumping of dropwise condensate on superhydrophobic surfaces is utilized to promote liquid return to the evaporator. The cooling system consists of water/vapor enclosed by two closely spaced parallel plates, a superhydrophilic evaporator and a superhydrophobic condenser. The hotspots on the evaporator drive the working fluid to vaporize and then condense on the opposing plate. When multiple condensate drops coalesce together, the released surface energy propels the merged drop to jump perpendicularly back to the hotspots, completing the liquid return and sustaining the phase change process. The adaptive cooling is accomplished by the preferential evaporation of the working fluid at the hotspots and the rapid jumping return across the very short inter-plate distance. The jumping-condensate approach offers a unique combination of hotspot cooling capabilities: (i) rapid response to moving hotspots; (ii) adaptive cooling for minimal thermal gradients; and (iii) passive cooling independent of external forces. Through integrated experimental and numerical investigations that are guided by simple scaling laws, the self-propelled jumping condensate will be studied in the context of adaptive hotspot cooling. In terms of interfacial transport phenomena, the project is expected to yield physical insights to surface-energy-powered jumping processes, which are widely observed in nature and potentially useful for improving industrial condensers. In terms of thermal transport processes, the project offers a fundamentally new mechanism for condensate return in phase change systems and a novel approach for adaptive thermal management of moving hotspots. This project is potentially transformative in enabling the thermal management of mobile hotspots which bottleneck the performance of state-of-the-art microprocessors and power electronics. The proposed research is also applicable to the promotion of self-sustained dropwise condensation, particularly for applications where favorable external forces may not exist (e.g. spacecraft cooling), and the development of biomimetic materials and systems harvesting interfacial energy (e.g. anti-dew materials). In addition to training graduate students and attracting minority undergraduates to STEM research, the project will strive to outreach to K-12 students and the general public. Through the PI?s ongoing CAREER program, a high school teacher will continue to translate cutting-edge research in the PI?s lab into refereed curricular units published at teachengienering.org. When appropriate, this project will also leverage the PI?s past successes with major media outlets such as the Discovery Channel to disseminate the research findings.

CBET-1236373 Chuan-Hua ChenDuke UniversityMobile hotspots在电子系统中非常普遍，包括微处理器和电力电子，其计算任务和外部有效载荷不断变化。现有的冷却解决方案通常被设计用于固定热点（例如热电冷却器）或缓慢变化的热负载（例如平板热管），并且因此不足以解决移动热点的冷却挑战。本研究旨在开发一种新的相变冷却机制，用于热点的自适应热管理，其中利用超疏水表面上的滴状冷凝物的自推进跳跃来促进液体返回到蒸发器。冷却系统由两个紧密间隔的平行板包围的水/蒸汽、超亲水蒸发器和超疏水冷凝器组成。蒸发器上的热点驱动工作流体蒸发，然后在相对的板上冷凝。当多个冷凝液滴聚结在一起时，释放的表面能推动合并的液滴垂直跳回到热点，完成液体返回并维持相变过程。自适应冷却是通过工作流体在热点处的优先蒸发和跨越非常短的板间距离的快速跳跃返回来实现的。跳跃冷凝方法提供了热点冷却能力的独特组合：（i）对移动热点的快速响应;（ii）最小热梯度的自适应冷却;以及（iii）独立于外力的被动冷却。通过综合的实验和数值研究，由简单的标度律的指导下，自推进跳跃冷凝将在自适应热点冷却的背景下进行研究。在界面传输现象方面，该项目预计将产生对表面能量驱动的跳跃过程的物理见解，这在自然界中被广泛观察到，并可能有助于改善工业冷凝器。在热传输过程方面，该项目为相变系统中的冷凝物返回提供了一种全新的机制，并为移动热点的自适应热管理提供了一种新方法。该项目在实现移动的热点的热管理方面具有潜在的变革性，这些热点阻碍了最先进的微处理器和电力电子器件的性能。所提出的研究也适用于促进自维持滴状冷凝，特别是对于可能不存在有利外力的应用（例如航天器冷却），以及仿生材料和系统收获界面能（例如抗露材料）的开发。 除了培训研究生和吸引少数民族本科生参加STEM研究外，该项目还将努力向K-12学生和公众推广。通过PI？的正在进行的职业生涯计划，一个高中教师将继续翻译尖端研究的PI？在适当的时候，这个项目也将利用PI？我们过去曾成功地与探索频道等主要媒体合作，传播研究成果。