Investigation of thermo-fluid dynamics of two-phase capillary-pumped heat transfer devices

现代电子设备产生的功率越来越大，结构也越来越紧凑；因此，对更有效和更创新的冷却技术的需求也越来越大。目前使用的最有效的冷却技术之一是热管。热管已被广泛用于传递产生热量的部件，如计算机中的微处理器或航天器中的电子仪器，同时将温度保持在指定范围内。与传统冷却技术相比，这些设备的优势包括不需要移动部件、坚固耐用以及能够传递大量热量。为了满足苛刻的热冷却要求，新的热管设计不断涌现。本课题的研究重点是两种高效热管的设计：动脉热管和环路热管。尽管最近在设计这些系统方面取得了重要进展，但对某些业务方面的了解还远远不够。阻碍这些设备更先进开发的主要困难之一是缺乏现实的数学模型。热管的运行依赖于多孔结构中流体的相变。液体从多孔结构中的蒸发是最具挑战性的问题之一。由于所涉及的规模很小，实验工作也极具挑战性。拟议研究项目的主要目标是调查这些设备中遇到的具体故障机理，并提出设计解决方案，以确保稳定运行。本研究将通过实验和数值研究相结合的方式进行。重要的应用领域包括高端电子冷却，紧急情况下核反应堆的被动冷却，以及敏感的空间有效载荷。这项研究也旨在促进对多孔介质中相变及其数学模型的基本理解。加强对这一领域的了解对于进一步改进包括燃料电池、石油和化学加工行业在内的各种工程应用至关重要。

Modern electronic equipment is producing more power and becoming more compact; therefore, there is an increasing demand for more effective and innovative cooling techniques. One of the most efficient cooling techniques currently in use is heat pipes. Heat pipes have been extensively used to transfer excess heat from a heat-producing component such as a microprocessor in a computer or an electronic instrument in a spacecraft, while maintaining the temperature within a specified range. The advantages of these devices over conventional cooling techniques include lack of moving parts, robustness, and the ability to transfer large amounts of heat. To meet the challenging thermal cooling requirements, new heat pipe designs have been emerging. This proposed research project focuses on two highly efficient heat pipe designs: arterial and loop heat pipes. Although important progress has been made in the recent past in designing these systems, some operational aspects are far from being understood. One of the major difficulties hindering more advanced development of these devices is the absence of realistic mathematical models. Heat pipe operation relies on the phase change of fluid in a porous structure. The evaporation of liquid from a porous structure is among the most challenging problems. Experimental work is also highly challenging because of the very small scales involved. The primary goal of the proposed research project is to investigate specific failure mechanisms encountered in these devices and propose design solutions to ensure a stable operation. The research will be carried out through both experimental and numerical investigation. The important application areas include high-end electronics cooling, passive cooling of nuclear reactors after an emergency, and sensitive space payloads. This research study also aims to contribute to the fundamental understanding of phase change in porous media and its mathematical modeling. An enhanced understanding in this field is critical to further improvements in a wide variety of engineering applications, including fuel-cell, petroleum and chemical processing industries.