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The control of temperature and humidity in spacecraft cabins is a vital component of environmental-control and life-support systems. Separating the two phases (i.e., water and air) that result from cooling air for humidity control represents a major technical challenge in the microgravity environment of space. With NASA funding, Bend Research has developed a membrane-based condensate-recovery heat exchanger (CRX) to address this challenge. The CRX offers substantial advantages in simplicity, reliability, mass, and volume over competing technologies. The high heat transfer and mass transfer in this device promise to provide superior humidity control without the need for complex mechanical separators. Moreover, these high transfer rates are achieved with minimal pressure drop, reducing power requirements.

Long duration missions in space will require regenerative processes to recover water for crew reuse. Membrane processes are attractive as a primary processor in water recovery systems (WRS) because of their design simplicity, low specific energy requirements, small size, and high water recovery. However, fouling has historically been regarded as a disadvantage of membrane-based processes. This fouling is often caused by micelle buildup on the membrane surface by high-molecular-weight organics (e.g., from soaps and laundry detergents). This paper describes a two-stage fouling-resistant ultrafiltration (UF)/reverse osmosis (RO) prototype subsystem, which was designed and constructed for a WRS in the Life Support Systems Integration Facility (LSSIF) at NASA Johnson Space Center (NASA/JSC). The first stage of the subsystem is a tube-side-feed hollow-fiber UF module that removes contaminants that tend to foul spiral-wound modules.