Description: Future manned exploration spacecraft will need to operate in challenging thermal environments. State-of-the-art technology for active thermal control relies on sublimating water ice and venting the vapor overboard in very hot environments. This approach can lead to large loss of water and a significant mass penalty for the spacecraft. We propose to develop a Space Evaporator Absorber Radiator (SEAR) that uses heat pumping and energy storage by LiCl/water absorption to enable thermal control without venting water even in the most adverse thermal conditions. The LiCl absorber technology has the potential to absorb over 800 kJ per kg of system mass, compared to phase change heat sink systems that typically achieve ~50 kJ/kg. Successful, subscale tests have already shown the potential for significant mass savings and radiator size reduction. We propose to develop an experimental package that will enable SEAR testing on ISS. In Phase I we will prove feasibility by assessing thermal environments for future exploration spacecraft, designing the thermal control system, and producing a conceptual design for an ISS test package. In Phase II we will design, build, and test a prototype experimental package suitable for demonstrating SEAR performance in an ISS internal rack.

Benefits: NASA can use the SEAR in active thermal control systems for future, manned exploration spacecraft. A key application will be manned lunar orbiters, which will experience extreme, cyclic thermal environments. The SEAR can save hundreds of kilograms of water and store more thermal energy than conventional systems that employ sublimators or phase-change materials. The SEAR technology can also be used as a heat rejection system for future exploration space suits. SEAR systems can save a tremendous amount of water compared to conventional venting systems.

SEAR technology can be adapted for use as a compact, regenerative, heat-driven dehumidification system for terrestrial applications where small size and light weight are critical. The system enables the same performance as liquid desiccant systems but without the complexity of recirculating liquid solution. The SEAR could be used in either a swing bed or enthalpy wheel type configuration. Applications include vehicular climate control systems and container based, industrial dehumidification systems.