SP‐100 high‐temperautre advanced radiator development

Rovang, Richard D.; Hunt, Maribeth E.; Dirling, R. B.; Hölzl, R.

doi:10.1063/1.40128

Cited by 8 publications

(5 citation statements)

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“…The C-C wall thickness is driven by the required armor thickness to protect the heat pipe against meteoroids a function of heat pipe's exposed area to space (Determan, 2003), and not by the internal pressure of the alkali-metal working fluid. In the SP-100 program, C-C heat pipes with integral fins have been successfully manufactured using a T-300 fiber, an angle interlocking weave architecture, and pitch densification (Rovang et al, 1991). Burst tests showed that a C-C shell with a diameter of 2.54 cm and a wall thickness of 0.864 mm (C-C bulk density = 1,650. kg/m 3 ) withstands an internal pressure as high as ~ 4.1 MPa.…”

Section: Description Of Radiator Heat Pipesmentioning

confidence: 99%

“…Because of their redundant and reliable operation and efficient spreading and rejection of the waste heat, heat pipes could markedly reduce the mass of the radiator. The choices of the working fluid and the design and operation temperature of the radiator heat pipes determine their performance and hence, the specific mass of the radiator (Moriarty and Determan, 1989;Rovang et al, 1991). For radiator temperatures of 350 K to 800 K, the present choices of working fluids with increasing temperature are water, cesium, rubidium, and potassium.…”

Section: Introductionmentioning

confidence: 98%

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Radiator Heat Pipes with Carbon-Carbon Fins and Armor for Space Nuclear Reactor Power Systems

Tournier¹,

El‐Genk²

2005

AIP Conference Proceedings

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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 (~ 2 mm-thick) provides both structural strength and protection against meteoroids impacts. The cross-section area of the Dshaped 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.

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Section: Description Of Radiator Heat Pipesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Radiator Heat Pipes with Carbon-Carbon Fins and Armor for Space Nuclear Reactor Power Systems

Tournier¹,

El‐Genk²

2005

AIP Conference Proceedings

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“…These armor thicknesses are sufficient to withstand the nominal pressure of the water vapor in the heat pipes (< 2.5 MPa). Heat pipes with integral C-C fins have been successfully manufactured using a T-300 fiber, an angle interlocking weave architecture, and pitch densification (Rovang et al, 1991;Juhasz and Rovang, 1995). Burst tests showed that a C-C shell with a diameter of 2.54 cm and a thickness of only 0.864 mm (C-C bulk density is 1650 kg/m 3 ) could withstand an internal pressure greater than 4.1 MPa.…”

Section: Design Of Water Heat Pipes and Radiator Panelsmentioning

confidence: 99%

“…The baseline radiator panel design in Fig. 17 capitalizes on demonstrated operation and lifetime of liquid metal heat pipes during the SP-100 program (Rovang et al, 1991;Josloff et al, 1994;Marriott and Fujita, 1994;Juhasz & Rovang, 1995).…”

Section: Radiator Heat Pipes Designmentioning

confidence: 99%

“…In these power systems, liquid-metal and water heat pipes have also been proposed for the heat rejection radiator panels, depending on the heat rejection temperature (e.g., Ranken, 1982;Angelo and Buden, 1985;El-Genk, Buksa and Seo, 1988;Moriarty and Determan, 1989;Gunther, 1990;Trujillo et al, 1990;Rovang et al, 1991;Harty and Mason, 1993;Marriott and Fujita, 1994;Josloff et al, 1994;Juhasz and Rovang, 1995;Tournier, 2004a and2006a;Schmitz et al, 2005;Tournier and El-Genk, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Uses of Liquid-Metal and Water Heat Pipes in Space Reactor Power Systems

El‐Genk¹,

Tournier²

2011

Frontiers in Heat Pipes

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Water and liquid-metal heat pipes are considered for redundant and passive cooling of nuclear reactors and redundant operation of light-weight heat rejection radiators of space reactor power systems. The systems operate continuously for many years independent of the Sun, are enabling of deep space exploration and could provide 10's of kilowatts of electrical power for lunar and Martian outposts. Space reactors typically operate at 900 K -1400 K could be cooled using liquid-metal heat pipes with either sodium (900 -1100 K) or lithium (1100 K-1400 K) working fluids. The heat rejection temperatures dictate the working fluid of the radiator heat pipes; potassium for 600 -800 K, rubidium for 500 -700 K, and water for < 500 K. These working fluids would be frozen prior to starting up the power systems in orbit or at destination. The startup of water and liquid-metal heat pipes from a frozen state is complex, involving a number of non-linear mass and heat transport processes that require implementing appropriate procedures, depending on the type of working fluid. This paper reviews operation and design constraints pertinent to the uses of water and liquidmetal heat pipes in space reactor systems, and the modeling capabilities of the startup from a frozen state. In addition to models validation, results of design optimization of liquid-metal and water heat pipes in a number of space reactor power systems are presented and discussed.

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