Constant Conductance Heat Pipe
Sealed Ammonia Heat Pipe with Sintered Wick
A constant conductance heat pipe is a sealed two-meter tube containing an ammonia working fluid and a sintered-metal wick that passively transfers thermal energy from equipment sources to radiator panels. Utilizing capillary action to pump fluid with zero electrical power, a standard two-kilogram unit transports 500 watts of heat independent of gravity orientation. Operating in lunar vacuum and abrasive regolith conditions, the all-welded aluminum or stainless steel housing provides dust-tolerant fluid containment designed for a 50-year operational lifetime.
Sealed ammonia or methanol heat pipes with sintered-metal wick transferring heat passively from sources to radiator panels.
Purpose
Sealed ammonia or methanol heat pipes with sintered-metal wick transferring heat passively from sources to radiator panels.
Context
Child of L2-PTC-HPIPE within the Lunar Ark system
Principles
- ▸Ammonia working fluid for spacecraft temperature range
- ▸Sintered-metal wick (Cu, Mo, or Ni) provides capillary pumping
- ▸Sealed all-welded construction for long life
- ▸Heat transport ~100-1000 W per pipe
- ▸Conductance independent of orientation in 1/6 g
Typical implementations
- ▸NASA Glenn heat pipe R&D heritage
- ▸ISS thermal control heat pipes
- ▸Honeywell space-grade heat pipes
- ▸Spacecraft thermal control handbook
Lunar considerations
- ▸Long-life sealed design
- ▸Independent of gravity orientation
- ▸Lunar dust-tolerant (sealed)
Specifications
Functional
| primary function | Sealed ammonia or methanol heat pipes with sintered-metal wick transferring heat passively from sources to radiator panels. |
| heat transport w | 500 |
| length m | 2 |
Physical
| mass kg | 2 |
| materials | 316L SS or aluminum housing, Sintered Cu/Mo wick, Ammonia working fluid |
| vacuum compatibility | True |
Operational
| power consumption w | 0 |
| thermal range c | -40, 70 |
| lifetime years | 50 |
| mtbf hours | 1000000 |
Interfaces
Provides
- Passive heat transfer from sources to radiators
Requires
- Heat pipe fabrication
- Replacement
Cite this entry
Lunar Ark Codex. "Constant Conductance Heat Pipe" (L3-PTC-HPIPE-CONST). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PTC-HPIPE-CONST
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.