ACT Logo
|ADVANCED COOLING TECHNOLOGIES
0
Cart Icon
Contact Us
  • Thermal Solutions
    • Passive Thermal Solutions
      • Heat Pipes
        • HiK Plates­™/ Heat Pipe Assemblies
        • Pulsating Heat Pipes
        • Vapor Chambers
        • High Temperature Heat Pipes
      • Loop Thermosyphon
      • Phase Change Based Solutions
        • PCM Heat Sinks
      • Liquid Cold Plates
    • Active Thermal Management Solutions
      • Liquid Cooling
      • Pumped Two-Phase
      • Liquid-Air HX
      • Tekgard® ECUs
      • Vaphtek™ ECU
      • Tekgard® Chillers
    • Embedded Computing Solutions
      • ICE-Lok®
      • VME/ VPX Card Frames
      • Conduction Cooled Chassis
      • Liquid Cooled Chassis
    • Enclosure Cooling Products
      • HSC (Heat Sink Coolers)
      • HPC (Heat Pipe Coolers)
      • TEC (Thermoelectric Coolers)
      • VCC (Vapor Compression Coolers)
      • Enclosure Cooling Selection Tool
    • Space Thermal Control
      • Constant Conductance Heat Pipes
      • Variable Conductance Heat Pipes
      • Space Copper-Water Heat Pipes
      • Loop Heat Pipes
      • Space VPX
      • Liquid Cooling
    • HVAC Energy Recovery
      • AAHX
      • WAHX
  • Engineering Services
    • Research & Development
      • Our Research & Development Team
      • Emerging Technology
      • Technical Papers
      • Other Research Interests
    • Product Development
    • Space Thermal & Structural Analysis
    • Manufacturing
    • Lifecycle Management
  • Industries
    • Energy
      • Wind Energy
      • Nuclear Energy
      • Power Conversion
      • Energy Storage
      • HVAC Energy Recovery
    • Space
    • HVAC Energy Recovery
    • Defense
    • Medical
    • Data Centers
    • Other
  • Resources
    • Blog
    • Calculators & Selection Tools
      • AAHX Selection Tool
      • Enclosure Cooling Selection Tool
      • Heat Pipe Calculator
      • PCM Calculator
      • WAHX Selection Tool
    • Publications
      • Published Articles
      • Patents
      • Technical Papers
    • Learning Center
      • Heat Pipe Learning Center
      • Pumped Two-Phase Learning Center
      • PCM Learning Center
      • HVAC Learning Center
      • Videos
      • eBooks
      • Brochures
      • Case Studies
      • Webinars
    • Find your Rep
  • Shop
    • Sealed Enclosure Coolers
    • Heat Pipe Coolers
      • Heat Pipe Cooler Accessories
    • Heat Sink Coolers
      • Heat Sink Cooler Accessories
    • Thermoelectric Coolers
    • Vapor Compression Coolers
  • About
    • Careers
    • Events
    • News
    • Sustainability
    • ACT Leadership
  • Contact
  • Thermal Solutions
    • Passive Thermal Solutions
      • Heat Pipes
        • HiK Plates­™/ Heat Pipe Assemblies
        • Pulsating Heat Pipes
        • Vapor Chambers
        • High Temperature Heat Pipes
      • Loop Thermosyphon
      • Phase Change Based Solutions
        • PCM Heat Sinks
      • Liquid Cold Plates
    • Active Thermal Management Solutions
      • Liquid Cooling
      • Pumped Two-Phase
      • Liquid-Air HX
      • Tekgard® ECUs
      • Vaphtek™ ECU
      • Tekgard® Chillers
    • Embedded Computing Solutions
      • ICE-Lok®
      • VME/ VPX Card Frames
      • Conduction Cooled Chassis
      • Liquid Cooled Chassis
    • Enclosure Cooling Products
      • HSC (Heat Sink Coolers)
      • HPC (Heat Pipe Coolers)
      • TEC (Thermoelectric Coolers)
      • VCC (Vapor Compression Coolers)
      • Enclosure Cooling Selection Tool
    • Space Thermal Control
      • Constant Conductance Heat Pipes
      • Variable Conductance Heat Pipes
      • Space Copper-Water Heat Pipes
      • Loop Heat Pipes
      • Space VPX
      • Liquid Cooling
    • HVAC Energy Recovery
      • AAHX
      • WAHX
  • Engineering Services
    • Research & Development
      • Our Research & Development Team
      • Emerging Technology
      • Technical Papers
      • Other Research Interests
    • Product Development
    • Space Thermal & Structural Analysis
    • Manufacturing
    • Lifecycle Management
  • Industries
    • Energy
      • Wind Energy
      • Nuclear Energy
      • Power Conversion
      • Energy Storage
      • HVAC Energy Recovery
    • Space
    • HVAC Energy Recovery
    • Defense
    • Medical
    • Data Centers
    • Other
  • Resources
    • Blog
    • Calculators & Selection Tools
      • AAHX Selection Tool
      • Enclosure Cooling Selection Tool
      • Heat Pipe Calculator
      • PCM Calculator
      • WAHX Selection Tool
    • Publications
      • Published Articles
      • Patents
      • Technical Papers
    • Learning Center
      • Heat Pipe Learning Center
      • Pumped Two-Phase Learning Center
      • PCM Learning Center
      • HVAC Learning Center
      • Videos
      • eBooks
      • Brochures
      • Case Studies
      • Webinars
    • Find your Rep
  • Shop
    • Sealed Enclosure Coolers
    • Heat Pipe Coolers
      • Heat Pipe Cooler Accessories
    • Heat Sink Coolers
      • Heat Sink Cooler Accessories
    • Thermoelectric Coolers
    • Vapor Compression Coolers
  • About
    • Careers
    • Events
    • News
    • Sustainability
    • ACT Leadership
  • Contact
0
Cart Icon View Cart
Satellite Electronics Box Cooling

The Anchor Node Mission for the International Lunar Network (ILN) has a Warm Electronics Box (WEB) and a battery, both of which must be maintained in a fairly narrow temperature range using a variable thermal conductance link. During the day, the thermal link must transfer heat from the WEB electronics to the radiator as efficiently as possible, to minimize the radiator size. On the other hand, the thermal link must be as ineffective as possible during the Lunar night to keep the electronics and battery warm with minimal power, even with the very low temperature (100 K) heat sink.

Trade study

A trade study was conducted that examined five different variable thermal links: 1. Pumped Loop, 2. Thermal Switch, 3. Variable Conductance Heat Pipe (VCHP), 4. Loop Heat Pipe (LHP), and 5. LHP with bypass valve. The table compares the potential thermal links.

Figure 1. Anchor Node with WEB Located in Middle.

Table 1. Comparison of Potential Thermal Links.

Technology AttributesMechanical Heat SwitchVCHPMini Loop Heat PipeMechanically Pumped Coolant Loop
Heat Transfer Capacity Range, W1 to 201 to over 10010 to over 10025 to over 500
Active/Passive SystemPassivePassivePassiveActive
Configuration FlexibilityInflexible, needs to be located close to the heat sinkFlexibleVery flexible, can easily transfer heat over large distances, over a meterVery Flexible, can transfer heat over very long distances
Heat Collection Flexibility (at source)Constrained to small foot printConstrained to small foot printConstrained to small foot printNo constraint on foot print
Heat Rejection Flexibility (at sink)Constrained to small foot printConstrained to small foot printNo constraint on foot printNo constraint on foot print
Typical mass, kg0.10 to 0.120.3 to 0.50.3 to 0.54 to 20
Conductance, W/K On0.4 to 0.52010 to 155 to 10
Conductance, W/K Off0.02 to 0.0250.01 to 0.040.01 to 0.030.03 to 0.05
Electric Power, WNone1-2 for tight thermal control1 for “off condition” 5 for start up (a few min.)3 to 10 for “on condition” (including electronics)
HeritageExcellent (test on Mars)Excellent for grooved wicksExcellent for SpaceExcellent for Space

Figure 2. ILN Loop Heat Pipe Thermal Switch Concept with Bypass Valve.

Mechanically pumped loops were dropped from further consideration, since they are not passive, and require power, which is limited on the Anchor Node. Thermal Switches were dropped due to their low thermal conductance.

The variable thermal link could be:

  1. Loop Heat Pipe (LHP)
  2. Loop Heat Pipe (LHP) with bypass valve
  3. Variable Conductance Heat Pipe (VCHP) with internal reservoir

The table compares LHP and VCHP variable thermal links. Either the LHP or the VCHP could be used as the variable thermal link. Both have similar “on” and “off” thermal conductances, both have flown in space, and both have similar masses.

Table 3. Comparison of Loop Heat Pipe and Variable Conductance Heat Pipe Variable Links

 LHPVCHP
Working FluidPropyleneAmmonia
Mass0.3 kg0.45 kg
Shutdown Power0 to 2 W0 W
Start-Up Heater5 W0 W
Conductance – On~ 15 W/K~20 W/K
Conductance – Off0.01 W/K0.04 W/K (all Al)0.008 (5 in. SS)
TRL Level – Conventional99
Radiator Coverage by CondenserFullPartial, unless Raised
May require Radiator CCHPsNoYes

A mini- Loop Heat Pipe (LHP) has the highest TRL level. However, supplying 1 W of power through the 14-day Lunar night requires roughly 5 kg of mass. A mini-LHP with a bypass valve requires more development and validation but eliminates the electrical shut-down power. A VCHP with a hybrid wick requires the most development. The benefit is that it would be much less expensive to fabricate than a loop heat pipe. ACT is currently working with NASA Marshall to develop the mini-LHP with bypass valve, and the VCHP.

Top Up facing arrow in a square
Page Index
  1. Trade study
  2. The variable thermal link could be:
Related Resources
Loop Heat Pipes Icon for Loop Heat Pipes
ACT Logo
Advanced Cooling Technologies, Inc.
1046 New Holland Avenue
Lancaster, Pennsylvania 17601, USA
(717) 295-6061 Contact Our Experts
linkedin youtube twitter facebook
  • shop products online
  • sitemap
  • privacy policy
  • terms & conditions
  • ISO9001 & AS9100 CERTIFIED, ITAR REGISTERED

Copyright 2025. All rights reserved.