Development of a 4K GM/JT Refrigerator for Maglev Vehicle

Publisher Summary This chapter focuses on the development of a Gifford-McMahon/Joule-Thomson(GM/JT) refrigerator for Maglev vehicle in partnership with Central Japan Railway Company and Toshiba Corporation. Commercial GM/JT refrigerators has been used for radio astronomy and other laboratory systems, however they had not been applied to Maglev vehicle because of the small refrigeration capacity due to the low efficiency. In addition, the refrigerator for Maglev vehicle has to be operated under very restricted environment. The constraints for designing the refrigerator are listed in the chapter. On-board helium refrigerators require large capacity, high efficiency and reliability even under severe environmental conditions. Principal Specifications of an on-board refrigerator are illustrated in the chapter. Major efforts have been made to improve the refrigeration capacity and efficiency with considering reliabilities. There were mainly three aspects to improve refrigeration capacity and efficiency–optimizing the pressure condition in refrigeration system, improvement of compressor, and improvement of GM expander.