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Testing of a Loop Heat Pipe Subjective to Variable AccelerationsThe effect of accelerating forces on the performance of loop heat pipes (LHP) is of interest and importance to terrestrial and space applications. LHP's are being considered for cooling of military combat vehicles and for spinning spacecraft. In order to investigate the effect of an accelerating force on LHP operation, a miniature LHP was installed on a spin table. Variable accelerating forces were imposed on the LHP by spinning the table at different angular speeds. Several patterns of accelerating forces were applied, i.e. continuous spin at different speeds and periodic spin at different speeds and frequencies. The resulting accelerations ranged from 1.17 g's to 4.7 g's. This paper presents the second part of the experimental study, i.e. the effect of an accelerating force on the LHP operating temperature. It has been known that in stationary tests the LHP operating temperature is a function of the evaporator power and the condenser sink temperature when the compensation temperature is not actively controlled. Results of this test program indicate that any change in the accelerating force will result in a chance in the LHP operating temperature through its influence on the fluid distribution in the evaporator, condenser and compensation chamber. However, the effect is not universal, rather it is a function of other test conditions. A steady, constant acceleration may result in an increase or decrease of the operating temperature, while a periodic spin will lead to a quasi-steady operating temperature over a sufficient time interval. In addition, an accelerating force may lead to temperature hysteresis and changes in the temperature oscillation. In spite of all these effects, the LHP continued to operate without any problems in all tests.
Document ID
20000101592
Document Type
Preprint (Draft being sent to journal)
Authors
Ku, Jentung
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Ottenstein, Laura
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Kaya, Taril
(International Space Univ., Inc. Toulouse, France)
Rogers, Paul
(Army Tank-Automotive Research and Development Command Warren, MI United States)
Hoff, Craig
(Kettering Univ. Flint, MI United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2000
Subject Category
Fluid Mechanics And Thermodynamics
Meeting Information
30th International Conference on Environmental Systems(Toulouse)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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