Freeze Tolerant Water Azeotrope Radiators

The “Freeze Tolerant Water Azeotrope Radiator” is a heat rejection technology that can survive the 14 day lunar night without trace heaters or other energy sources. Its purpose is to reject multi-kilowatt thermal loads (10’s to 100’s of kWt) during hot operations plus be able to survive a lunar night anywhere on the moon whether operating or in standby mode. Combining large deployable radiator panels with embedded water azeotrope heat pipes that allow flexure at the joints provides a system which can be stowed and mobilized or deployed and operational with the ability to survive freeze and thaw cycles as needed depending on the mission and fault tolerance of its parent system. This freeze tolerant and mobile radiator subsystem can integrate with power generation and distribution, mobility assets, and In-Situ resource processing plants. It can be designed to operate on the moon or Mars with and without gravity assistance.  This is achieved by utilizing the unique properties of water azeotropes that turn to a slush consistency when frozen which greatly reduces structural stresses. This allows the heat pipe pressure vessel to be designed with thin walls that increase heat transfer, reduce mass, and allow thin walled bellows or like structures needed for deployable operations. Phase I will focus on down selecting water azeotrope fluids, heat pipe design, and deployable radiator architecture. Subscale testing of a loop heat pipe and thermosyphon are expected to help support decisions leading to a phase II program. If selected, phase II will include a deployable multi-panel radiator in a thermal vacuum chamber that demonstrates freeze thaw operations from 400K (TBD) down to 80K and back for multiple cycles. Phase III will be target a lunar lander demonstration. Markets for this technology will include all moon to Mars systems that require freeze tolerant heat rejection with two phase fluids.