Advanced Supported Liquid Membranes for Carbon Dioxide Control in Extravehicular Activity Applications



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44th International Conference on Environmental Systems


Developing a new, robust, portable life support system (PLSS) is currently a high priority for NASA in order to support longer and safer extravehicular activity (EVA) missions. One of the critical PLSS functions is maintaining the carbon dioxide (CO2) concentration in the suit at acceptable levels. Although the Metal Oxide (MetOx) canister has worked well, it has a finite CO2 adsorption capacity. Consequently, the unit would have to be larger and heavier to extend EVA times. Therefore, new CO2 control technologies must be developed to meet mission objectives without increasing the size of the PLSS. Although recent work has centered on sorbents that can be regenerated during the EVA, this strategy increases the system complexity and power consumption. A simpler approach is to use a membrane that selectively vents CO2 to space. A membrane has many advantages over current technology: it is a continuous system with no theoretical capacity limit, it requires no consumables, and it requires no hardware for switching beds between absorption and regeneration. Unfortunately, conventional gas separation membranes do not have adequate selectivity for use in the PLSS. However, the required performance could be obtained with a supported liquid membrane (SLM), which consists of a microporous material filled with a liquid that selectively reacts with CO2 over oxygen (O2). In a current Phase II Small Business Innovative Research project, Reaction Systems has developed a new reactive liquid that has effectively zero vapor pressure, making it an ideal candidate for use in an SLM. The SLM function has been demonstrated with representative pressures of CO2, O2, and water. The SLM vents moisture to space in addition to being effective for CO2 control. Therefore, this project has demonstrated the feasibility of using an SLM to control CO2 in an EVA application.


Tucson, Arizona
The 44th International Conference on Environmental Systems was held in Tuscon, Arizona, USA on 13 July 2014 through 17 July 2014.
David T. Wickham, Reaction Systems, Inc., USA
Kevin J. Gleason, Reaction Systems, Inc., USA
Jeffrey R. Engel, Reaction Systems, Inc., USA
Scott W. Cowley, Colorado School of Mines, USA
Cinda Chullen, NASA Johnson Space Center, USA