Loop Heat Pipe
LHP for Long-Distance Heat Transport
A loop heat pipe is a thermal transport device that circulates an ammonia working fluid through a nickel sintered capillary wick within a 316L stainless steel or aluminum housing. Operating with zero electrical power consumption, it routes vapor and liquid through separate smooth-bore lines to transport more than 2 kilowatts of heat across 10 meters without flow blocking. Sustaining continuous operation in the lunar environment requires a dust-tolerant, sealed 15-kilogram construction rated for a 50-year lifetime and one million hours mean time between failures, supported by replaceable evaporator and condenser modules.
Loop heat pipe (LHP) using capillary evaporator + smooth-bore vapor/liquid lines for long-distance (>5 m) heat transport at high power.
Purpose
Loop heat pipe (LHP) using capillary evaporator + smooth-bore vapor/liquid lines for long-distance (>5 m) heat transport at high power.
Context
Child of L2-PTC-HPIPE within the Lunar Ark system
Principles
- ▸Evaporator with primary + secondary wick
- ▸Separate liquid and vapor lines (no flow blocking)
- ▸Heat transport >2 kW over >10 m
- ▸Robust to multiple evaporators / condensers
- ▸Long-life sealed all-welded design
Typical implementations
- ▸NASA Glenn LHP research (heritage)
- ▸ISS LHP thermal control
- ▸ESA Aerospace LHP heritage
- ▸Spacecraft long-distance heat transfer
Lunar considerations
- ▸Long mission requires sealed long-life design
- ▸Lunar dust-tolerant
- ▸Replaceable evaporator/condenser modules
Specifications
Functional
| primary function | Loop heat pipe (LHP) using capillary evaporator + smooth-bore vapor/liquid lines for long-distance (>5 m) heat transport at high power. |
| heat transport w | 2000 |
| length m | 10 |
Physical
| mass kg | 15 |
| materials | 316L SS / Al housing, Nickel sintered 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
- Long-distance heat transport (~2 kW)
- Reactor cold-side LHP
Requires
- LHP fabrication
Cite this entry
Lunar Ark Codex. "Loop Heat Pipe" (L3-PTC-HPIPE-LOOP). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PTC-HPIPE-LOOP
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.