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The fuel cell is a high-efficiency, low-emission electro-chemical device adaptable to a host of power generation applications. A bipolar plate is used to feed reactants to the fuel cell electrodes and to collect current. The bipolar plates for proton exchange membrane fuel cells (PEMFCs) have been traditionally fabricated from graphite, owing to its high electrical conductivity and high corrosion resistance. However, the large mass and volume of graphite make it an unlikely choice for automotive fuel cell bipolar plates. The use of lightweight metals such as aluminum is attractive, due to its low mass and volume, low-cost, and ease of manufacturing. Unfortunately, high corrosion resistance and electrical conductivity requirements for fuel cell components preclude uncoated aluminum. Physical Sciences Inc.

Reversible adsorption on zeolite molecular sieve material allows selective removal of carbon dioxide (CO2) from spacecraft air without the use of expendables. The four-bed molecular sieve (4BMS) CO2 removal subsystem chosen for use on space station is based on proven Skylab technology and provides continuous CO2 removal from the cabin atmosphere and concentration for further processing downstream or venting overboard. A 4BMS subsystem has also been chosen to remove CO2 from air in the Systems Integration Research Facility (SIRF) at NASA/Johnson Space Center (JSC). After installation in the SIRF in 1992, the subsystem underwent extensive testing in which cycle time, process air flow rate, and process air inlet CO2 composition were varied. In order to obtain performance data required for integration, the subsystem was operated under both nominal and off-nominal conditions. Results of this testing are presented.