Variable Conductance Heat Pipe
VCHP with Non-Condensable Gas Reservoir
A variable-conductance heat pipe is a passive thermal management device constructed from a 316L stainless steel housing, a copper wick, and an ammonia working fluid paired with an argon gas reservoir. The 3 kg assembly transports up to 200 W of heat while maintaining a setpoint stability of 1 °C with zero electrical power consumption. Because lunar surface operations demand decades of maintenance-free reliability without vulnerable active control electronics, the sealed unit relies on the passive expansion of non-condensable gas to block condenser area as thermal loads shift, supporting a 50-year operational lifetime.
Variable-conductance heat pipe (VCHP) using non-condensable gas reservoir to passively regulate temperature.
Purpose
Variable-conductance heat pipe (VCHP) using non-condensable gas reservoir to passively regulate temperature.
Context
Child of L2-PTC-HPIPE within the Lunar Ark system
Principles
- ▸Non-condensable gas (Ar, He) blocks portion of condenser
- ▸Reservoir volume tuned for setpoint temperature
- ▸Self-regulating without active control
- ▸Long-life sealed gas reservoir
- ▸Used for instruments needing tight thermal control
Typical implementations
- ▸NASA Glenn VCHP research
- ▸Aerospace instrument thermal control
- ▸Cryogenic VCHP for IR detectors
Lunar considerations
- ▸Passive regulation eliminates control electronics
- ▸Long-life sealed design
- ▸Coupled to L3-COM-TIME-USOC for clock temperature stability
Specifications
Functional
| primary function | Variable-conductance heat pipe (VCHP) using non-condensable gas reservoir to passively regulate temperature. |
| setpoint stability c | 1 |
| heat transport w | 200 |
Physical
| mass kg | 3 |
| materials | 316L SS housing, Cu wick, Ammonia + Ar reservoir |
| vacuum compatibility | True |
Operational
| power consumption w | 0 |
| thermal range c | -40, 70 |
| lifetime years | 50 |
| mtbf hours | 1000000 |
Interfaces
Provides
- Temperature-regulated heat path
- Clock temperature stability
Requires
- VCHP fabrication
Cite this entry
Lunar Ark Codex. "Variable Conductance Heat Pipe" (L3-PTC-HPIPE-VAR). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PTC-HPIPE-VAR
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.