GOALI: Pulsed sprays for cooling high power devices

对速度更快、功能更强大的设备日益增长的需求是科学技术的普遍趋势。从高速运输到个人设备再到数据中心，高效、廉价的热管理是目前推动技术发展的关键瓶颈之一。喷雾冷却，特别是基于沸腾的冷却过程，有望在新型3D微电子、电光器件和制造工艺（如快速3D打印）的发展中发挥越来越大的作用。目前，大多数设备和大型数据中心采用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，需要具有相变冷却（例如沸腾和蒸发）附加优势的液体冷却。这项工作追求脉冲喷雾的使用，以更好地了解用沸腾和蒸发流体冷却大功率设备的基本限制。此外，这项工作将有助于收集系统的流体流场和热输运数据-这两者对于预测和理解相变冷却不稳定性至关重要。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顿弗罗斯特效应。该项目有三个主要的研究和教育重点：(1)建立精细的喷雾冷却能力，具有中等面积，半微米纹理表面/设备和先进的光学测量技术，用于系统表征时空温度和流场。(2)了解温度达到和超过莱顿弗罗斯特点时结构表面的薄膜厚度、瞬时和时间平均传热特性。(3)研究多喷嘴脉冲式、喷雾式/喷射式冷却的控制分配方法。优化的半芯结构表面的应用为这项研究增加了一个变革性的利基。这种结构不仅可以在可变重力环境下“延长”液体到固体的润湿，超出其固有的润湿长度，而且还可以通过使用尖端的半锥形（各向异性）柱来减少液滴飞溅、反弹和夹带。该项目支持许多实践，教育和工业推广组件，促进从K-12活动到本科高级设计项目到博士学位的独特研究的更广泛影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.