Radiator Heat Pipes with Carbon-Carbon Fins and Armor for Space Nuclear Reactor Power Systems
- Institute for Space and Nuclear Power Studies, The University of New Mexico, Albuquerque, NM 87131 (United States)
Technologies for Space Reactor Power Systems are being developed to enable future NASA's missions early next decade to explore the farthest planets in the solar system. The choices of the energy conversion technology for these power systems require radiator temperatures that span a wide range, from 350 K to 800 K. Heat pipes with carbon-carbon fins and armor are the preferred choice for these radiators because of inherent redundancy and efficient spreading and rejection of waste heat into space at a relatively small mass penalty. The performance results and specific masses of radiator heat pipes with cesium, rubidium, and potassium working fluids are presented and compared in this paper. The heat pipes operate at 40% of the prevailing operation limit (a design margin of 60%), typically the sonic and/or capillary limit. The thickness of the carbon-carbon fins is 0.5 mm but the width is varied, and the evaporator and condenser sections are 0.15 and 1.35 m long, respectively. The 400-mesh wick and the heat pipe thin metal wall are titanium, and the carbon-carbon armor ({approx} 2 mm-thick) provides both structural strength and protection against meteoroids impacts. The cross-section area of the D-shaped radiator heat pipes is optimized for minimum mass. Because of the low vapor pressure of potassium and its very high Figure-Of-Merit (FOM), radiator potassium heat pipes are the best performers at temperatures above 800 K, where the sonic limit is no longer an issue. On the other hand, rubidium heat pipes are limited by the sonic limit below 762 K and by the capillary limit at higher temperature. The transition temperature between these two limits for the cesium heat pipes occurs at a lower temperature of 724 K, since cesium has lower FOM than rubidium. The present results show that with a design margin of 60%, the cesium heat pipes radiator is best at 680-720 K, the rubidium heat pipes radiator is best at 720-800 K, while the potassium heat pipes radiator is the best performer and lightest at higher temperatures {>=} 800 K.
- OSTI ID:
- 20630599
- Journal Information:
- AIP Conference Proceedings, Vol. 746, Issue 1; Conference: STAIF 2005: Conference on thermophysics in microgravity; Conference on commercial/civil next generation space transportation; 22. symposium on space nuclear power and propulsion; Conference on human/robotic technology and the national vision for space exploration; 3. symposium on space colonization; 2. symposium on new frontiers and future concepts, Albuquerque, NM (United States), 13-17 Feb 2005; Other Information: DOI: 10.1063/1.1867218; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON
CESIUM
DESIGN
EVAPORATORS
HEAT PIPES
POTASSIUM
RADIATORS
REACTOR OPERATION
REACTOR SAFETY
RUBIDIUM
SAFETY MARGINS
SPACE POWER REACTORS
STEAM CONDENSERS
TITANIUM
VAPOR PRESSURE
WASTE HEAT
WORKING FLUIDS
NESDPS Office of Nuclear Energy Space and Defense Power Systems