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This paper describes a Stirling Cycle Refrigerator that has been built and tested by Stirling Technology Company (STC) for the NASA Marshall Space Flight Center (MSFC). Its intended application is the space station food refrigerator freezer. The Stirling Cycle Refrigerator described herein has few moving parts, is nontoxic to both humans and the environment, is insensitive to gravity, and has a moderate efficiency. Its temperature setpoint is adjustable, making it adaptable to other space station applications including a -70 °C freezer and freeze drier, a -183 °C freezer, and a -196 °C snap freezer. Test results have been very promising, with a Coefficient of Performance (COP) of 1.1 at -26 °C (-15 °F) and a heat load of 130 watts. Reliability tests on individual components and the entire Stirling Cycle Refrigerator system show a 10-year life is possible. In addition, the benefits of using this technology for the space station refrigerator freezer will be described.

Results of the final design phase of a free-piston hydraulic Advanced Stirling Conversion System were reported at the 1991 IECEC [1]. This project was funded by the United States Department of Energy and administered by NASA Lewis Research Center through Sandia National Laboratories. The final design met program objectives with the exception of a shortfall in nominal power output and efficiency, and an exceeded weight limit. These deficiencies were due to new bellows design data. Four Stirling convertor configurations were evaluated as part of the Technology Assessment Task, which included combinations of alternative technologies. Alternative technologies included gas and flexural bearings, moving magnet and stationary magnet linear alternators, and seven different control options. This paper describes the approach of the Technology Assessment and summarizes the conclusions and recommendations.