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Experimental Investigation of the Effect of Gravity on Heat Pipe StartupThis paper describes an experimental investigation of the effect of the gravity pressure head on the startup of a heat pipe under the reflux mode. In this study, a heat pipe with internal axial grooves was placed in an upright position with two different tilt angles relative to the horizontal plane. Heat was applied to the evaporator at the bottom and cooling was provided to the condenser at the top. The liquid-flooded evaporator was divided into seven segments along the axial direction, and electrical heaters were attached to each segment. Heat was applied to individual heaters in various combinations and sequences. Test results show that as long as an individual evaporator segment was flooded with liquid initially, a superheat was required to vaporize the liquid in that segment. The amount of superheat required for liquid vaporization was a function of gravity pressure head imposed on that evaporator segment. The most effective way to start the heat pipe was to apply a heat load with a high heat flux to the lowest segment of the evaporator. This paper describes an experimental investigation of the effect of the gravity pressure head on the startup of a heat pipe under the reflux mode. In this study, a heat pipe with internal axial grooves was placed in an upright position with two different tilt angles relative to the horizontal plane. Heat was applied to the evaporator at the bottom and cooling was provided to the condenser at the top. The liquid-flooded evaporator was divided into seven segments along the axial direction, and electrical heaters were attached to each segment. Heat was applied to individual heaters in various combinations and sequences. Test results show that as long as an individual evaporator segment was flooded with liquid initially, a superheat was required to vaporize the liquid in that segment. The amount of superheat required for liquid vaporization was a function of gravity pressure head imposed on that evaporator segment. The most effective way to start the heat pipe was to apply a heat load with a high heat flux to the lowest segment of the evaporator.
Document ID
20180003962
Acquisition Source
Goddard Space Flight Center
Document Type
Presentation
Authors
Ku, Jentung (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
July 16, 2018
Publication Date
June 10, 2018
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
GSFC-E-DAA-TN54817
Meeting Information
Meeting: International Heat Pipe Conference
Location: Pisa
Country: Italy
Start Date: June 10, 2018
End Date: June 14, 2018
Sponsors: Pisa Univ.
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Heat Pipes
Thermal Control Systems

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