Session
Session VIII: 17th Annual Frank J. Redd Student Scholarship Competition
Abstract
The advancement of small satellite technology relies on the development of effective thermal management systems that can be made smaller, safer, and more robust. This paper presents the results and analysis of a nucleate boiling experiment in sustained microgravity aboard the Space Shuttle Endeavor (STS-108). Bubble growth and departure were observed from a single and a braid of three 0.16 mm diameter and 80 mm long nickel-chromium resistive wires. Analysis showed that the braided wire provides a unique surface configuration to enhance the onset of boiling. The braid of wires was also observed to produce several bubble explosions; this is the first observation of such phenomenon under microgravity conditions. Bubble explosions are being researched on Earth due to their ability to remove large amounts of heat. Large spherical bubbles enclosing the wire were not observed, in contrast to many previous thin wire microgravity boiling experiments which often lead to the burnout of the heating element in microgravity. Measured bubble propagation was in good agreement with several prediction models based on drag forces. The effects of bubble formation, departure, and propagation on the temperature gradients in the fluid were analyzed. Applications for the development of microgravity heat transfer systems based on boiling mechanisms are discussed, along with the potential for further research utilizing small satellite technology.
Presentation Slides
Thin Wire Nucleate Boiling of Water in Sustained Microgravity
The advancement of small satellite technology relies on the development of effective thermal management systems that can be made smaller, safer, and more robust. This paper presents the results and analysis of a nucleate boiling experiment in sustained microgravity aboard the Space Shuttle Endeavor (STS-108). Bubble growth and departure were observed from a single and a braid of three 0.16 mm diameter and 80 mm long nickel-chromium resistive wires. Analysis showed that the braided wire provides a unique surface configuration to enhance the onset of boiling. The braid of wires was also observed to produce several bubble explosions; this is the first observation of such phenomenon under microgravity conditions. Bubble explosions are being researched on Earth due to their ability to remove large amounts of heat. Large spherical bubbles enclosing the wire were not observed, in contrast to many previous thin wire microgravity boiling experiments which often lead to the burnout of the heating element in microgravity. Measured bubble propagation was in good agreement with several prediction models based on drag forces. The effects of bubble formation, departure, and propagation on the temperature gradients in the fluid were analyzed. Applications for the development of microgravity heat transfer systems based on boiling mechanisms are discussed, along with the potential for further research utilizing small satellite technology.
