Development of a highly reliable helium refrigeration system––R&D of a highly reliable helium refrigeration system (oil-free type)

✍ Scribed by Hiroshi Asakura; Nobuyoshi Saji; Seiichiro Yoshinaga; Takehiko Ishizawa; Masamitsu Ikeuchi; Hideharu Yanagi; Yasuhiro Hirao; Kazuhiro Kitagawa

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 204 KB
• Volume: 42
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/s0011-2275(02)00030-9

✦ Synopsis

The present paper reports the development of the highly reliable refrigeration system (three types), which is applied for 70 MW class superconducting generators. R&D of the oil-free turbo type: In the turbo type of advanced refrigeration system, a complete oil free 80 K cold compressor was developed. Moreover, the cold compressor driven by a coaxial turbine was developed to enhance the system efficiency and to save space. R&D of the oil-free screw type: In the oil-free screw rotors, taper rotors were planned to maintain a radial clearance between male and female rotors and the casing, to compensate their thermal deformation because of the heat of compression. Moreover, a seal technique was established that used a magnetic fluid and gas seals to prevent lubricating oil from bearings and the timing gear chamber into the rotor housing, under a higher rotational speed of 25,000 rpm.