Hollow Fiber Space Suit Water Membrane Evaporator Development for Lunar Missions 2009-01-2371

The Space Suit Water Membrane Evaporator (SWME) is a baseline heat rejection technology that was selected to develop the Constellation Program lunar suit. The Hollow Fiber (HoFi) SWME is being considered for service in the Constellation Space Suit Element Portable Life Support Subsystem to provide cooling to the thermal loop via water evaporation to the vacuum of space. Previous work [1] described the test methodology and planning that are entailed in comparing the test performance of three commercially available HoFi materials as alternatives to the sheet membrane prototype for SWME: (1) porous hydrophobic polypropylene, (2) porous hydrophobic polysulfone, and (3) ion exchange through nonporous hydrophilic-modified Nafion^®. Contamination tests were performed to probe for sensitivities of the candidate SWME elements to the organic and non-volatile inorganic constituents that are expected to be found in the target feedwater source, i.e., the potable water that is provided by the vehicle.

The resulting presence of precipitate in the coolant water could plug the pores and tube channels, thus affecting SWME performance. From this prior work, a commercial porous hydrophobic HoFi was selected that will satisfy both the sensitivity question and the need to provide 800 W of heat rejection.

This paper describes the trade studies, design method ology, and HoFi test data that are used to design a full-size HoFi test article for future testing in the summer of 2009.