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The International Space Station (ISS) requires advanced life support to continue its mission as a permanently-manned space laboratory and to reduce logistic resupply requirements as the Space Shuttle retires from service. Additionally, as humans reach to explore the moon and Mars, advanced vehicles and extraterrestrial bases will rely on life support systems that feature in-situ resource utilization to minimize launch weight and enhance mission capability. An obvious goal is the development of advanced systems that meet the requirements of both mission scenarios to reduce development costs by deploying common modules. A high pressure oxygen generating assembly (HPOGA) utilizing a high differential pressure (HDP) water electrolysis cell stack can provide a recharge capability for the high pressure oxygen storage tanks on-board the ISS independently of the Space Shuttle as well as offer a pathway for advanced life support equipment for future manned space exploration missions.

Submarines, aircraft, and manned space vehicles require oxygen for human respiration. On-board generation through the electrolysis of water is a practical means of obtaining this oxygen. Proton exchange membrane ceils have been in production for many years. Existing system designs are based on maintaining the oxygen and hydrogen sides of the cells at nearly equal pressures. Recent technical advances allow high differential pressure cell stacks, which permit direct discharge of one gas at low or ambient pressure while supplying the other gas at high pressure. This capability simplifies system and component designs and results in improved reliability, safety, and operability. This paper updates the development status of high differential pressure SPE® electrolysis cells and provides test results from prototype assemblies.

A two year test program has been initiated to evaluate the effects of extended duration operation on a solid polymer electrolyte Oxygen Generator Assembly (OGA); in particular the cell stack and membrane phase separators. As part of this test program, the OGA was integrated into the Marshall Space Flight Center (MSFC) Water Recovery Test (WRT) Stage 10, a six month test, to use reclaimed water directly from the water processor product water storage tanks. This paper will document results encountered and evaluated thus far in the life testing program.

Submarines, aircraft, and manned space vehicles require oxygen for human respiration. Onboard generation through the electrolysis of water is a practical means of obtaining this oxygen. Proton exchange membrane cells have been in production for many years. Existing system designs are based on maintaining the oxygen and hydrogen sides of the cells at nearly equal pressures. Recent technical advances allow high differential pressure cell stacks, which permit direct discharge of one gas at low or ambient pressure while supplying the other gas at high pressure. This capability simplifies system and component designs and results in improved reliability, safety, and operability. This paper updates the development status of high differential pressure SPE ® electrolysis cells and describes systems for applying this technology to submarine and aircraft applications.

The International Space Station (ISS) redesign made operational and interface requirements changes to the previous Space Station Freedom baseline. These changes include Oxygen Generation Assembly (OGA) production only on the daylight side of each orbit; nitrogen interface pressure reduction to 100 +/- 10 psia (690 +/- 69 kPa); and available production rates of nominal, nominal +10%, and nominal -10%. In 1994 a test program was initiated at MSFC to verify OGA capabilities for cyclic operation. The liquid feed solid polymer electrolyzer from the 1990 OGA Comparative Test was refurbished and modified as required. This paper describes the operation of the test unit, and presents a discussion of the test data and test results.