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Power System for Venus Surface ExplorationA radioisotope power and cooling system is designed to provide electrical power for a probe operating on the surface of Venus. Most foreseeable electronics devices and sensors cannot operate at the 450 C ambient surface temperature of Venus. Because the mission duration is substantially long and the use of thermal mass to maintain an operable temperature range is likely impractical, some type of active refrigeration may be required to keep electronic components at a temperature below ambient. The fundamental cooling parameters are the cold sink temperature, the hot sink temperature, and the amount of heat to be removed. In this instance, it is anticipated that electronics would have a nominal operating temperature of 300 C. Due to the highly thermal convective nature of the high-density (90 bar CO2) atmosphere, the hot sink temperature was assumed to be 50 C, which provided a 500 C temperature of the cooler's heat rejecter to the ambient atmosphere. The majority of the heat load on the cooler is from the high temperature ambient surface environment on Venus, with a small contribution of heat generation from electronics and sensors. Both thermoelectric (RTG) and dynamic power conversion systems were analyzed, based on use of a standard isotope (General-purpose heat source, or GPHS) brick. For the radioisotope Stirling power converter configuration designed, the Sage model predicts a thermodynamic power output capacity of 478.1 watts, which slightly exceeds the required 469.1 watts. The hot sink temperature is 1200 C, and the cold sink temperature is 500 C. The required heat input is 1740 watts. This gives a thermodynamic efficiency of 27.48 %. It is estimated that the mechanical efficiency of the power converter design is on the order of 85 %, based on experimental measurements taken from 500-watt power class, laboratory-tested Stirling engines. The overall efficiency is calculated to be 23.36 %. The mass of the power converter is estimated at approximately 21.6 kg. Additional information is included in the original extended abstract.
Document ID
20050203986
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Landis, Geoffrey A.
(NASA Glenn Research Center Cleveland, OH, United States)
Mellott, Kenneth
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 8, 2013
Publication Date
July 10, 2002
Subject Category
Spacecraft Propulsion And Power
Meeting Information
Meeting: Seventh European Space Power Conference
Location: Como
Country: Italy
Start Date: May 9, 2005
End Date: May 13, 2005
Funding Number(s)
WBS: WBS 22-319-20-B1
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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