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A fuel cell which uses pure hydrogen sulfide as fuel and a solid electrolyte of ceria stabilized with yttria (YSC) has been proposed, with the configuration H2S, Pt/YSC/Pt, O2 (air), operating at temperatures of 600 to 800° C. Initial experiments will use platinum electrodes, with subsequent runs using various perovskite type electrodes. The YSC electrolye system exhibits better ionic conductivity than the more familiar YSZ electrolytes, and thus the fuel cell will operate at a lower temperature range. Cell component manufacture, cell experiments, and analytical techniques are discussed.

A molten carbonate fuel cell has been successfully tested as a carbon dioxide concentrator. We, here, examine cathode performance in terms of removal efficiency, voltage loss and current efficiency at oxidant CO2 levels typical of manned space cabin atmospheres. A system design based on this concept has the potential advantages of small size, low component cost and high current efficiency at low-CO2 levels. The disadvantages arrive from the penalties associated with the high-temperature operation.

A system comprised mainly of 90 electrochemical cells has been designed for use as a CO2 concentrator in a manned spacecraft. Cabin air, with a CO2 partial pressure of about 3 mm Hg is passed across the cathode of an oxygen-hydrogen fuel cell. It is concentrated through the carbonate electrolyte and expelled into the hydrogen-filled anode cavity. The total system, as well as the individual cell design, is described. Experimental results are shown for the full (90 cell) system and also for smaller scale (1 and 3 cell) tests. Excellent consistency among the tests was found. A steady state analytical model has been developed and numerical simulations of the system have been carried out. The model consists of two parts. The first part is established based on the rate equations which govern each of the processes controlling the CO2 transfer in the system. It is a non-linear boundary value problem which is solved by a shooting method.