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Thermal Vacuum Testing of a Helium Loop Heat Pipe for Large Area CryocoolingFuture NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and to verify its ability to cool large areas or components in the 3 degrees Kelvin temperature range. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by simply applying power to both the capillary pump and the evaporator plate without pre-conditioning. It could adapt to a rapid heat load change and quickly reach a new steady state. Heat removal between 10 megawatts and 140 megawatts was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.
Document ID
20160008954
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ku, Jentung
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Robinson, Franklin
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
July 12, 2016
Publication Date
July 10, 2016
Subject Category
Engineering (General)
Fluid Mechanics And Thermodynamics
Report/Patent Number
GSFC-E-DAA-TN31792
ICES-2016-25
Report Number: GSFC-E-DAA-TN31792
Report Number: ICES-2016-25
Meeting Information
Meeting: International Conference on Environmental Systems
Location: Vienna
Country: Austria
Start Date: July 10, 2016
End Date: July 14, 2016
Sponsors: American Society of Mechanical Engineers, International Conference On Environmental Systems, Inc., American Inst. of Chemical Engineers
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Thermal Control Systems
Loop Heat Pipes
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