Search

The Constrained Vapor Bubble (CVB) is a wickless, grooved heat pipe and is the first, full-scale fluids experiment flown on the U.S. module of the International Space Station. The CVB promises to provide new insight into the operation of a heat pipe in space. It is a relatively simple device constructed from a spectrophotometer cuvette and uses pentane as the working fluid. The pentane flows within the corners of the cuvette due to a curvature gradient in the liquid menisci associated with the cuvette corners. The curvature of the liquid interface can be determined by viewing the meniscus through the transparent quartz walls. Extremely accurate temperature and pressure measurements were obtained in addition to the images. In the article, the results from the first two CVB modules—a dry calibration module and a wet heat pipe module—are presented. We show that the axial temperature profiles are significantly different in space. The heat pipes were seen to operate at a higher pressure and higher temperature ...

The constrained vapor bubble (CVB) experiment is an experiment in thermal fluid science currently operating on the International Space Station. Flown as the first experiment on the Fluids Integrated Rack on the Destiny module of the US part of the space station, the experiment promises to provide new and exciting insights into the working of a wickless micro heat pipe in the micro-gravity environment. The CVB consists of a relatively simple setup — a quartz cuvette with sharp corners partially filled with pentane as the working fluid. Along with temperature and pressure measurements, the curvature of the pentane menisci formed at the corners of the cuvette can be determined using optical measurements. This is the first time the data collected in space environment is being presented to the public. The data shows that, while the performance of the CVB heat pipe is enhanced due to increased fluid flow, the loss of convection as a heat loss mechanism in the space environment, leads to some interesting consequences. We present some significant differences in the operating characteristics of the heat pipe between the space and Earth’s gravity environments and show that this has important ramifications in designing effective radiators for the space environment.