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Evaluating Heat Pipe Performance in 1/6 g Acceleration: Problems and ProspectsHeat pipes composed of titanium and water are being considered for use in the heat rejection system of a fission power system option for lunar exploration. Placed vertically on the lunar surface, the heat pipes would operate as thermosyphons in the 1/6 g environment. The design of thermosyphons for such an application is determined, in part, by the flooding limit. Flooding is composed of two components, the thickness of the fluid film on the walls of the thermosyphon and the interaction of the fluid flow with the concurrent vapor counter flow. Both the fluid thickness contribution and interfacial shear contribution are inversely proportional to gravity. Hence, evaluating the performance of a thermosyphon in a 1 g environment on Earth may inadvertently lead to overestimating the performance of the same thermosyphon as experienced in the 1/6 g environment on the moon. Several concepts of varying complexity have been proposed for evaluating thermosyphon performance in reduced gravity, ranging from tilting the thermosyphons on Earth based on a cosine function, to flying heat pipes on a low-g aircraft. This paper summarizes the problems and prospects for evaluating thermosyphon performance in 1/6 g.
Document ID
Document Type
Conference Paper
Jaworske, Donald A.
(NASA Glenn Research Center Cleveland, OH, United States)
McCollum, Timothy A.
(Hagerstown Community College Hagerstown, MD)
Gibson, Marc A.
(NASA Glenn Research Center Cleveland, OH, United States)
Sanzi, James L.
(Sest, Inc. Middleburgh Heights, OH, United States)
Sechkar, Edward A.
(ASRC Aerospace Corp. Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
February 7, 2011
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
Meeting Information
Nuclear and Emerging Technologies for Space (NETS-2011)(Albuquerque, NM)
Distribution Limits
Public Use Permitted.

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