May 8, 2013
News Release
Market launch of the world’s first turbo refrigerator used for coolingsuperconducting power equipment
Taiyo Nippon Sanso Corporation (TNSC; President: Shinji Tanabe) announces thedevelopment and market launch of its new turbo refrigerator that uses neon gas as arefrigerant and is capable of cooling superconducting power equipment to -200°C andbelow.
1. Background of Development
The need for refrigerators suitable for cooling superconducting power equipment isincreasing as commercial research commences for this type of equipment, which isanticipated to play a key role in the development of energy-saving power technologies.
It is thought that cooling capacity ranging from 2kW to 10kW is necessary to reachtemperatures close to -200°C, the operating temperature range of refrigerators used
for cooling superconducting power equipment. However, the cooling capacity ofcommercial cryocoolers is 1kW or less. In addition, such units require regular
maintenance due to the inclusion of rubbing parts.
TNSC manufactures and operates cryogenic facility technology, including air
separation plants and liquefaction units. Based on its technology, TNSC hasdeveloped a 2kW turbo refrigerator that has a long maintenance interval and issuitable for cooling superconducting power equipment.
Furthermore, the New Energy and Industrial Technology Development
Organization (NEDO) supported the development of such refrigerators by undertaking
the Technological Development of Yttrium-based Superconducting Power Equipment
Project (from April2008 to–March 2013). This project enabled TNSC to develop aturbo refrigerator used for cooling the world’s first 2MVA superconducting
transformers, contributing to the successful supply of electrical current.

2. Overview of the Device
The new turbo refrigerator improves efficiency and reliability thanks to the adoptionof neon gas and magnetic bearings. Consequently, this machine is the world’s first touse neon gas as a working fluid for cooling superconducting power equipment. Thismachine also uses the Turbo-Brayton Cycle with a particular eye to reducing
refrigerator maintenance.
The new turbo refrigerator enhances turbo machine efficiency and reliability
owing to refrigerants that use neon gas, which has a molecular weight heavier thanthat of helium gas.
In addition, the turbo-compressor and turbo-expander, which are the main
components of the new turbo refrigerator, incorporate magnetic bearings. Magnetic
bearings use electromagnetic force to levitate the rotating machine shaft. This design
eliminates any mechanical contact between the shaft and bearing surface, realizing amaintenance-free rotating machine.
Until now, the cooling capacity of conventional cryocoolers was adjusted
using an electric heater installed within the refrigerator. However, the cooling
capacity of the new turbo refrigerator can be adjusted by regulating theturbo-compressor’s rotational speed, which significantly improves efficiency during
partial load operations.
3. Future Development
There is currently a global upswing in projects for developing superconducting power
cables and other related power equipment. Against this backdrop, the market releaseof the world’s first turbo refrigerator is a significant step forward in the developmentof practical applications for superconducting power equipment. TNSC plans toenhance its product lineup by the end of the current fiscal year with the developmentof a 10kW turbo refrigerator suitable for cooling long-distance power transmission
cables.
Note: Turbo-Brayton Cycle
The basic Brayton Cycle generates cooling power through four processes: 1. adiabaticcompression; 2. cooled at constant pressure; 3. adiabatic expansion; and 4. heated atconstant pressure. The Turbo-Brayton Cycle involves processes 1. and 3. within theturbo machine (turbo-compressor and turbo-expander).
After neon gas compressed by the turbo-compressor expels the heat generated
by compression into the atmosphere, adiabatic expansion occurs in the turbo-expander,
thus lowering the temperature of the neon gas. Following this, the neon gas absorbs
the surrounding heat, which flows back into the turbo-compressor inlet. In an actualrefrigerator, a heat exchanger is inserted between the turbo-compressor andturbo-expander, which recovers cold energy to produce extremely low temperatures.

External view of the new turbo refrigerator (prototype)