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Loop Heat Pipe Transient Behavior Using Heat Source Temperature for Set Point Control with Thermoelectric Converter on ReservoirThe LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly done by cold biasing the reservoir and using electrical heaters to provide the required control power. With this method, the loop operating temperature can be controlled within 0.5K or better. However, because the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if the LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP was carried out to investigate the effects on the LHP operation when the control temperature sensor was placed on the heat source instead of the reservoir. In these tests, the LHP reservoir was cold-biased and was heated by a control heater. Test results show that it was feasible to use the heat source temperature for feedback control of the LHP operation. In particular, when a thermoelectric converter was used as the reservoir control heater, the heat source temperature could be maintained within a tight range using a proportional-integral-derivative or on/off control algorithm. Moreover, because the TEC could provide both heating and cooling to the reservoir, temperature oscillations during fast transients such as loop startup could be eliminated or substantially reduced when compared to using an electrical heater as the control heater.
Document ID
20110015224
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ku, Jentung (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Paiva, Kleber (Federal Univ. of Santa Catarina Santa Catarina, Brazil)
Mantelli, Marcia (Federal Univ. of Santa Catarina Santa Catarina, Brazil)
Date Acquired
August 25, 2013
Publication Date
July 31, 2011
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
GSFC.CP.4691.2011
Report Number: GSFC.CP.4691.2011
Meeting Information
Meeting: 9th Annual International Energy Conversion Engineering Conference
Location: San Diego, CA
Country: United States
Start Date: July 31, 2011
End Date: August 3, 2011
Distribution Limits
Public
Copyright
Public Use Permitted.

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