Kundan Akshay, Plawsky Joel L, Wayner Peter C
The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
Langmuir. 2015 May 19;31(19):5377-86. doi: 10.1021/acs.langmuir.5b00428. Epub 2015 May 7.
The Constrained Vapor Bubble (CVB) experiment concerns a transparent, simple, "wickless" heat pipe operated in the microgravity environment of the International Space Station (ISS). In a microgravity environment, the relative effect of Marangoni flow is amplified because of highly reduced buoyancy driven flows as demonstrated herein. In this work, experimental results obtained using a transparent 30 mm long CVB module, 3 mm × 3 mm in square cross-section, with power inputs of up to 3.125 W are presented and discussed. Due to the extremely low Bond number and the dielectric materials of construction, the CVB system was ideally suited to determining if dry-out as a result of Marangoni forces might contribute to limiting heat pipe performance and exactly how that limitation occurs. Using a combination of visual observations and thermal measurements, we find a more complicated phenomenon in which opposing Marangoni and capillary forces lead to flooding of the device. A simple one-dimensional, thermal-fluid flow model describes the essence of the relative importance of the two stresses. Moreover, even though the heater end of the device is flooded and the liquid is highly superheated, boiling does not occur due to high evaporation rates.
受限汽泡（CVB）实验涉及在国际空间站（ISS）微重力环境下运行的一种透明、简单的“无芯”热管。在微重力环境中，如本文所示，由于浮力驱动流大幅减少，马兰戈尼流的相对影响被放大。在这项工作中，展示并讨论了使用一个透明的30毫米长CVB模块（方形横截面为3毫米×3毫米）、功率输入高达3.125瓦时获得的实验结果。由于极低的邦德数和所用的介电材料，CVB系统非常适合确定由马兰戈尼力导致的干涸是否可能会限制热管性能，以及这种限制究竟是如何发生的。通过结合视觉观察和热测量，我们发现了一个更复杂的现象，即相反的马兰戈尼力和毛细力导致装置出现液泛。一个简单的一维热流体流动模型描述了这两种应力相对重要性的本质。此外，尽管装置的加热器端被液体淹没且液体高度过热，但由于高蒸发速率，并不会发生沸腾。
