Cryocoolers

Cryocoolers and Superconductivity Applied Technologies

From energy, computers, transportation, communication to familiar medical care, superconductivity applied technologies are considered to be used in various fields from various visions. This superconductivity is one of the ultimate physical properties brought from the field of ultra-low temperatures close to an absolute temperature (–273℃). Physical properties which we can not imagine in the ordinary temperatures where we live every day, appear by the interaction between the ions and electrons at ultra-low temperatures, where the electrical resistance drops to zero causing an object to levitate (Meissner effect), or enables ultra high-speed switching (Josephson effect). In 1911, superconductivity was discovered by a Dutchman for the first time, by cooling mercury to 4.2 K (Kelvin).

Since then, there has been a remarkable evolution in refrigeration technology over about 100 years. Accompanying this evolution, the research and development for superconductivity has also achieved remarkable progress. Superconductivity is considered to be the key technology in the 21st century. When using this applied technology for energy only as an example, the role of this technology will become even more important as a technology to utilize the earth's energy to the maximum, while protecting the beautiful global environment. Utilizing our experience in refrigeration technology cultivated over many years, NTE sells a unique compressor dedicated for helium and high performance cryocoolers.

MRI

Magnetic resonance imaging systems (MRI) play an important role on sites for advanced medicine. Large size superconductive coils are indispensable for MRI systems, which produces images of inside the body by applying a strong magnetism to the human body. In order to maintain the coil in a superconductive state, cryocoolers are used as a refrigerator to maintain the liquid helium at low temperatures.

Superconducting Electric Power Generation and Power Storage Systems

Power generation utilizing superconductivity and power storage systems are expected to be one of the answers to solve energy issues in the future. Superconducting generators with a high utilization factor of energy will also play an important role in environmental issues, not only leading to the effective use of resources. Moreover, superconducting magnetic energy storage systems which enable the storing of large amounts of power will realize an ideal power supply system, where the required amount of power can be used in the required location as required.

What is a Refrigerator?

Refrigerators lower the temperature of objects using a refrigerant (helium). Every refrigerator basically has the same functions to lower the temperature by compression and expansion, but there are several types depending on the difference in the principle.

GM Refrigerator with No Restrictions in Installation Direction

This is a mechanical refrigerator in which the cooling agent reciprocates inside a cylinder to perform adiabatic expansion of the refrigerant gas to generate the coldness. The method to reciprocate the cooling agent in the GM refrigerator made by Sumitomo Heavy Industries, utilizes a crank mechanism to convert the motor rotation movement by the reciprocating motion. Furthermore, Sumitomo Heavy Industries devised a design for the two-stage cooling agent seals, and developed the world's first refrigerator with no restrictions on the installation direction of the 4K refrigerator.

Pulse Tube Refrigerator with Less Maintenance

The pulse tube refrigerator consists of a compressor, coolant storage unit and a simple tube called the pulse tube. The most significant difference from the GM refrigerator is that there is no reciprocating motion of the cooling agent in the cylinder, and less vibration while the refrigerator is in operation. Furthermore, since the cooling agent is fixed and there are fewer drive components compared with the GM refrigerator, the frequency of maintenance can be reduced. The features of the pulse tube refrigerator made by Sumitomo Heavy Industries is that the two-stage refrigerating performance can be used effectively, by improving the first-stage refrigerating performance to realize a reduction in the amount of heat intrusion from outside.

Highly Efficient JT4K Refrigerator

The JT4K refrigerator is a 4K refrigerator where the Joule Thomson (JT) adiabatic expansion is added to a two-stage type refrigerator. The 4K refrigerator utilizes the latent heat of the helium, and the performance is extremely efficient compared with the adiabatic expansion type refrigerators, such as the GM refrigerator and the pulse tube refrigerator. One of the features is that there is far less temperature fluctuation, since the latent heat is utilized.

Refrigerator Applications

GM refrigerator: Radio telescopes and superconductive magnets for MRI
Pulse tube refrigerator: Magnets for NMR and dilution refrigeration pre-coolers
JT4K refrigerator: Superconductive magnets for accelerators and sensor cooling