Thermal Switch Development for Small Rover Lunar Night Survival



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2024 International Conference on Environmnetal Systems


A passive two-phase thermal switch concept has been developed to provide a high thermal turndown ratio to enable lunar night survival of small lunar rovers. Thermal switches are designed to reduce heat transfer in the Off state, and maximize it when in the On state. The thermal switch developed utilizes a flexible metal bellows containing a two-phase working fluid. Switching between On and Off states is passively driven by the vapor temperature and pressure of the working fluid. At temperatures below the designed switching temperature, the vapor pressure is reduced, and the bellows is contracted and not in contact with the heat sink. At temperatures above the designed switching temperature, the vapor pressure increases, causing the bellows to expand and contact the heat sink for efficient heat rejection. The designed switching temperature is determined by the effective balance of forces on the bellows. A prototype thermal switch for a small lunar rover with propylene as the bellows working fluid was designed, fabricated, and tested. In this design a radiator panel is offset from the main rover frame to which the avionics are mounted, with the thermal switch situated between the frame and the radiator. Thermal vacuum test results demonstrated the ability of the thermal switch to thermally isolate the rover frame and payload from the radiator as the sink temperature decreased. These results are compared to thermal vacuum test results of a baseline rover frame in which the avionics are mounted directly to the radiator.


Nathan Van Velson, Advanced Cooling Technologies, Inc., USA
Roopesh Kumar, Advanced Cooling Technologies, Inc., USA
Calin Tarau, Advanced Cooling Technologies, Inc., USA
William G. Anderson, Advanced Cooling Technologies, Inc., USA
ICES104: Advances in Thermal Control Technology
The 53rd International Conference on Environmental Systems was held in Louisville, Kentucky, USA, on 21 July 2024 through 25 July 2024.


Thermal switch, Lunar night, Lunar night survival, Survive the lunar night, Two-phase heat transfer