Heat Exchanger Heaters
Fluid Loop Pre-Heater and Anti-Freeze System
Heat exchanger heaters, or fluid loop pre-heater and anti-freeze systems, are electric trace heating assemblies wrapped along active thermal control lines to prevent working fluids from freezing and to pre-heat lines prior to pump startup. In lunar surface installations, thermal control loops using ammonia face ambient conditions well below the fluid's -77.7 °C freezing point during unheated operations or extended safe modes across the lunar night. Utilizing self-regulating positive temperature coefficient or mineral-insulated cable along extended pipe runs, these heaters provide uniform heat distribution to prevent localized freezing, where a single unheated line segment can create an ice plug that completely blocks fluid circulation.
Heaters integrated with fluid loops preventing ammonia freezing during cold conditions
Purpose
Prevent thermal loop fluid from freezing during cold transients or startup
Context
Child of L2-TCS-HTR in the Active Thermal Control System
Principles
- ▸Trace heaters along fluid lines maintain minimum fluid temperature above freezing point
- ▸Ammonia freezes at -77.7C - well below lunar night temperatures in unheated areas
- ▸Pre-heaters bring fluid to operating temperature before pump startup
- ▸Heat tape wrapping provides uniform heating along extended pipe runs
Typical implementations
- ▸Raychem/nVent self-regulating heat trace cable
- ▸ISS ammonia loop heater design
- ▸Industrial freeze protection systems for chemical plants
Lunar considerations
- ▸Ammonia freezing at -77.7C could occur during extended safe mode on lunar night side
- ▸Self-regulating heat trace reduces power consumption as temperature rises
- ▸Heater failure on a single line segment could create ice plug blocking flow
Specifications
Functional
| primary function | Heaters integrated with fluid loops preventing ammonia freezing during cold conditions |
Physical
| materials | Self-regulating PTC heat trace cable, Mineral-insulated trace heater cable |
Interfaces
Provides
- Freeze protection for thermal fluid loops
Requires
- Power for trace heaters (~100-500W)
Cite this entry
Lunar Ark Codex. "Heat Exchanger Heaters" (L3-TCS-HTR-HXCH). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-TCS-HTR-HXCH
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.