GOALI: Pulsed sprays for cooling high power devices

对速度更快、功能更强大的设备的需求日益增长，这是科技领域普遍存在的趋势。从高速运输到个人设备再到数据中心，高效、廉价的热管理目前是推进技术包络的关键瓶颈之一。喷雾冷却，特别是基于沸腾的冷却工艺，预计将在新的3D微电子、电光设备和制造工艺(如快速3D打印)的开发中发挥越来越大的作用。目前，大多数设备和大型数据中心都是通过风机和水冷却通道相结合的方式进行冷却。然而，为了满足下一代更强大、更紧凑的设备和数据中心的散热需求，需要液体冷却并增加相变冷却(例如沸腾和蒸发)的好处。这项工作致力于使用脉冲喷雾来更好地了解用沸腾和蒸发液体来冷却大功率设备的基本极限。此外，这项工作将有助于收集系统的流体流场和热传输数据-这两个数据对于预测和了解相变冷却不稳定性都是至关重要的。本研究旨在全面了解脉冲喷雾冷却过程中的临界热流密度和莱登弗罗斯特效应。该项目有三个主要的研究和教育推动：(1)建立精细的喷雾冷却能力，具有中等面积、半芯状纹理的表面/设备和先进的光学计量系统，用于系统地表征时空温度和流场。(2)了解温度高于或超过莱登弗罗斯特温度的结构表面上的薄膜厚度、瞬时和时间平均的换热特性。(3)研究多喷嘴脉冲喷雾/喷射冷却的控制分配方法。优化的半芯吸水结构表面的应用为这项研究增加了一个变革性的利基。这种结构不仅将在可变重力环境中将液-固润湿扩展到其固有的润湿长度之外，还可以通过使用尖端的半锥形(各向异性)柱子来减少液滴的飞溅、反弹和夹带。该项目支持许多实践、教育和工业推广部分，促进更广泛的影响，从K-12活动到本科高级设计项目，再到博士学位的独特研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The increasing demand for faster and more powerful devices is a ubiquitous trend in science and technology. From high-speed transportation to personal devices to data centers, efficient, cheap thermal management is currently one of the key bottlenecks for advancing the technical envelope. Spray cooling, particularly with boiling-based cooling processes, is expected to play a growing role in the development of new 3D microelectronics, electro-optic devices, and manufacturing processes such as rapid 3D printing. Currently, most devices and large-scale data centers are cooled by a combination of air fans and water cooling channels. However, to meet the heat dissipation demands for the next generation of more powerful and more compact devices and data centers, liquid cooling with the added benefit of phase-change cooling (e.g., boiling and evaporation) is needed. This work pursues the use of pulsed sprays to better understand the fundamental limits of cooling high-power devices with boiling and evaporating fluids. Also, this work will facilitate the collection of systematic fluid flow-field and thermal transport data – both of paramount importance for predicting and understanding phase-change cooling instabilities. The research aims to fully understand the critical heat flux and Leidenfrost effects during pulsed spray cooling. The project has three major research and educational thrusts: (1) Establish refined spray cooling capabilities with moderate area, hemiwicking-textured surfaces/devices and advanced optical metrologies for systematic characterization of spatiotemporal temperature and flow-fields. (2) Understand the thin-film thickness and the instantaneous and time-averaged heat transfer characteristics on structured surfaces with temperatures up to and beyond the Leidenfrost point. (3) Study control allocation methodologies for pulsed, spray/jet cooling with multiple spray nozzles. The application of optimized hemiwicking-structured surfaces adds a transformative niche to this research. Such structures will not only ‘extend’ the liquid-to-solid wetting beyond its intrinsic wetting length in variable gravity environments, but can also reduce droplet splashing, rebound, and entrainment – via using sharp tipped, half-conical (anisotropic) pillars. The project supports many hands-on, educational, and industrial outreach components, facilitating broader impacts from K-12 activities to undergraduate senior design projects to distinctive research for doctoral degrees.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.