Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen

M. Iwakuma, K. Adachi, K. Yun, K. Yoshida, S. Sato, Y. Suzuki, T. Umeno, M. Konno, H. Hayashi, T. Eguchi, T. Izumi, Y. Shiohara

Research output: Contribution to journalConference article

Abstract

We developed a turbo-Brayton refrigerator with Ne gas as a working fluid for a 3θ- 66/6.9kV-2MVA superconducting transformer with coated conductors which was bath-cooled with subcooled LN2. The two-stage compressor and expansion turbine had non-contact magnetic bearings for a long maintenance interval. In the future, we intend to directly install a heat exchanger into the Glass-Fiber-Reinforced-Plastics cryostat of a transformer and make a heat exchange between the working fluid gas and subcooled LN2. In this paper we investigate the behaviour of subcooled LN2 in a test cryostat, in which heater coils were arranged side by side with a flat plate finned-tube heat exchanger. Here a He turbo-Brayton refrigerator was used as a substitute for a Ne turbo-Brayton one. The pressure at the surface of LN2 in the cryostat was one atmosphere. Just under the LN2 surface, a stationary layer of LN2 was created over the depth of 20 cm and temperature dropped from 77 K to 65 K with depth while, in the lower level than that, a natural convection flow of LN2 was formed and temperature was almost uniform over 1 m depth. The boundary plane between the stationary layer and the natural convection region was visible.

Original languageEnglish
Article number012026
JournalIOP Conference Series: Materials Science and Engineering
Volume101
Issue number1
DOIs
Publication statusPublished - Dec 18 2015
Event2015 Joint Cryogenic Engineering and International Cryogenic Materials Conferences, CEC/ICMC 2015 - Tucson, United States
Duration: Jun 28 2015Jul 2 2015

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Cryostats
Refrigerators
Liquid nitrogen
Cooling systems
Natural convection
Gases
Glass fiber reinforced plastics
Magnetic bearings
Fluids
Heat exchangers
Compressors
Turbines
Temperature

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)

Cite this

Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen. / Iwakuma, M.; Adachi, K.; Yun, K.; Yoshida, K.; Sato, S.; Suzuki, Y.; Umeno, T.; Konno, M.; Hayashi, H.; Eguchi, T.; Izumi, T.; Shiohara, Y.

In: IOP Conference Series: Materials Science and Engineering, Vol. 101, No. 1, 012026, 18.12.2015.

Research output: Contribution to journalConference article

Iwakuma, M. ; Adachi, K. ; Yun, K. ; Yoshida, K. ; Sato, S. ; Suzuki, Y. ; Umeno, T. ; Konno, M. ; Hayashi, H. ; Eguchi, T. ; Izumi, T. ; Shiohara, Y. / Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen. In: IOP Conference Series: Materials Science and Engineering. 2015 ; Vol. 101, No. 1.
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