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Extreme Temperature Heat Pipe and Loop Heat Pipe Solutions: -270°C to >2,000°C

With high-precision temperature control and rapid temperature recovery, plus long life under demanding conditions, Thermacore’s extreme temperature heat pipes are in action from the ocean floor to geosynchronous orbit.

high temperature heat pipePredictable thermal management at extremely high temperatures has helped improve processes from glass making to epitaxial deposition, while cryogenic thermal solutions are at work protecting sensitive detection devices in outer space — and in the medical laboratory and the home freezer unit. Thermacore customized extreme-temperature heat pipes also support large-scale industrial applications like oil-shale extraction, helping to maximize uptime and reduce energy and maintenance costs.

 

Low-Temperature (Cryogenic) Heat Pipe Advantages and Experience

  • Reliable operation in extremely low temperatures: -268° C to -73° C (5K to 200K)
    • Operated in space to remove 10 W of power
  • Proven in aerospace (satellite, space shuttle) applications
    • Cryocooler interfaces
    • Infrared sensor cooling
    • Medical technology heat removal
    • Refrigerator and freezer cooling
    • Flexible cable wick ensures high performance
    • Inert nitrogen working fluid for safest operation

Thermacore has extensive experience with developing thermal solutions for operating at cryogenic temperatures. Some of these solutions:

  • Heat Pipes
    • Ammonia (200K to 400K)
    • Ethane (120K to 300K)
    • Methanol (200K to 400K)
    • Nitrogen (65K to 120K)
    • Oxygen (80K to 140K)
    • Pentane (150K to 400K)
    • Propylene (120K to 335K)
  • Loop Heat Pipes
    • Ammonia (200K to 400K)
    • Ethane (120K to 300K)
    • Hydrogen
    • Neon
    • Oxygen (80K to 140K)
    • Propylene (120K to 335K)

Ammonia Heat Pipes (200K to 400K)

copper-water steel-ammonia heat pipeAmmonia heat pipes, or AHP, are used for those applications that require operation in the temperature range of 200K to about 400K. These heat pipes are available in 3" (76.2) through 18" (457) lengths and 0.25" (6.35) through .75" (15.8) diameters. These products are manufactured with a stainless steel envelope, sintered stainless steel wick structure and ammonia as the working fluid. Due to the properties of ammonia and the sintered powder metal wick structure, gravity assistance is not required for operation, so the AHP can be operated in horizontal or gravity assisted position. The primary advantage is heat transport against gravity (the heat source located at an elevation higher than the condenser).

The location of the heat source is a key parameter to consider when evaluating your application. The adverse-gravity performance gives the customer versatility when addressing their thermal solution.
These heat pipes can also be bent and shaped to fit a specific application. For example, the heat pipe assembly pictured below, called a "Cascading" design, uses two stainless steel/ammonia heat pipes in conjunction with copper/water heat pipes to operate over a wide temperature range (-50º C to 70° C). The stainless steel/ammonia heat pipes operate from -50º C to about 30º C.

In this application, the stainless steel/ammonia heat pipes were linked in series rather then parallel to allow them to operate against gravity. At temperatures above 30º C, the copper/water heat pipe takes over and continues operation to 70º C.

Ethane Heat Pipes (120K to 300K)

ethane heat pipeEthane Heat Pipes (EHPs) are used for applications that require operation in the temperature range of 120K to about 300K. The EHP is typically fabricated with a stainless steel envelope, a sintered stainless steel wick structure and ethane as the working fluid. EHPs have been used for cooling a superconducting magnet from room temperature down to cryogenic temperatures in a Navy minesweeping application. (A single heat pipe could not cover the entire operating temperature range.) The solution was to use a cascade design. Two ethane heat pipes cooled the structure down to -40°C, after which two oxygen heat pipes cooled the structure the rest of the way down to the desired temperature.

Methanol Heat Pipes (200K to 400K)

Methanol Heat Pipes (MHPs) have a working range of -20°C to about 80°C and are a standard Thermacore product, available in standard diameters and lengths.

Methanol provides extreme-temperature performance because it does not freeze until approximately -95°C. Our heat pipes also use sintered powder metal wick structure which allows operation against gravity for more design versatility. These products are available in 3" (76.2) through 18" (457) lengths and 0.25" (6.35) through 0.75" (15.8) diameters, and are manufactured with a copper envelope, sintered copper wick structure and methanol as the working fluid. The MHP can be operated in a horizontal or gravity assisted position.

Their primary advantage is heat transport against gravity (heat source located at an elevation higher then the condenser). The location of the heat source is a key parameter to consider when evaluating your application. The adverse-gravity performance gives the customer design flexiblity when addressing their thermal solution.

Nitrogen Heat Pipes (65K to 120K)

Cryogenic heat pipes are used by NASA to remove heat in low-temperature environments from camaras and sensors that take pictures and detect objects in space.The exact configuration of the heat pipe is mission specific; however, a recently tested demonstration nitrogen heat pipe used a porous metal wick structure. A porous metal design was selected because experience shows these designs provide substantially higher adverse tilt capability than axially grooved designs (a feature which allows easier ground testing). The nitrogen porous metal wick heat pipe was operated at temperatures near 80K at adverse tilts up to 6.5 cm, as compared to tilts of about 0.5 cm for grooved designs. Adverse tilt capability is useful for operation under adverse acceleration.

Oxygen Heat Pipes (60K to 140K)

Oxygen Heat Pipes (OHPs) have also been proven to cool a superconducting magnet from room temperature to cryogenic temperatures for Navy minesweeping applications. A cascaded design used two ethane heat pipes to cool the structure to -40°C, after which two oxygen heat pipes cooled the structure the rest of the way down to the desired temperature.

Please contact a Thermacore representative to determine if an oxygen heat pipe is right for your application.

Propylene Heat Pipes (120K to 335K)

Propylene heat pipes (PHPs) are some of the most useful heat pipes for cryogenic applcations because they can cool from room temperature to a desired cryogenic temperature without assistance. In addition, propylene heat pipes are made from copper and can use the standard Thermacore sintered powder metal wick structure.

Please contact a Thermacore representative to determine if a propylene heat pipe is right for your application.

High Temperature Heat Pipe Advantages and Applications

  • High-precision temperature control and rapid temperature recovery
  • Isothermality at high temperature
  • Uniform material crystal growth
  • Thermal to electric energy conversion
  • Energy savings
  • High heat flux and power capability:
    • Lithium heat pipe operated at 126 kW/cm2
  • Wide range of working fluids available including:
    • Cesium: 300°C to 600°C
    • Potassium: 400°C to 1,000°C
    • Sodium: 500°C to 1,200°C
    • Lithium: 900°C to 1,700°C
  • Temperature uniformity:
    • < 10mK pressure-controlled IFL
  • High temperature materials
    • 300 Series Stainless Steels
    • Incoloy 800 and Inconel 600, 601, 718, 625
    • Haynes 230, 188, 214, Nickel and Hastelloy C
    • Titanium and Tantalum
    • Molybdenum and TZM
    • Rhenium, Niobium & Tungsten
  • Reliable operation, long life, reliability
    • Thermacore High Temperature Heat Pipe Life Testing
      • Continuous life testing — longest continuous in the world
      • Sodium heat pipe operating for over 15 years

Applications

  • Isothermal Furnace Liners (standard & custom)
    • Thermocouple Calibration
    • Crystal Growth
    • Vapor Deposition Black
    • Black Body Radiators
    • DiffusionAnnealing
    • Temperature Calibration
    • Thermophysical Property Characterization
    • Materials Processing
  • Energy Conversion
    • Thermionic Converters
    • Alkali Metal Thermal-to-Electric Converters (AMTEC)
    • Stirling Engine Interfaces
    • Solar Receivers
    • Chemical Processing
    • Engine Components
    • Aerospace Leading Edges
    • Rocket Nozzles
    • High-Temperature Space Radiators
    • Magnetoplasmadynamic (MPD) Thrusters
    • Isotope Separation
    • Fusion Applications

If your product or process involves high-temperature heat transfer, or involves high heat flux cooling, Thermacore has the design and fabrication experience required to provide the best thermal solution.


 

Thermal management challenge? Take the first step towards the solution for you. Please contact a Thermacore technical representative or e-mail mailto:info@thermacore.com for more information on our thermal solution technologies.

 
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