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Cooling with Liquid Helium
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
The normal boiling point for liquid helium is 4.223 K. It is both the lowest temperature liquid and remains a liquid all the way down to the lowest possible temperature, absolute zero. Solid helium is only formed under a pressure greater than 25 atmospheres. Rather than converting into the more orderly state of a solid as its temperature is lowered, a feature that is true with all other substances, helium transitions to an alternate and more highly ordered superfluid liquid phase, termed helium II, as its saturation temperature is reduced below the so-called lambda point temperature of 2.1768 K. From a physics perspective, the behavior and properties of helium II is an intensely interesting field exhibiting a rich variety of unique features. For the purposes of this handbook, the heat transfer properties of helium II will be briefly described near the end of the chapter. However, even the liquid phase of helium above the lambda point, termed helium I, provides a variety of fluid properties that are sufficiently different from room temperature liquids that one should have them in mind when using liquid helium for cooling purposes.
MRI Magnets
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2022
Michael Parizh, Wolfgang Stautner
Helium cost is rising. It costs much more these days than 10 years ago. 10 years ago, the factory cost of liquid helium was as low as $3/liter. Now, the per liter cost has risen up to $15 in the US. In other parts of the world, the liquid helium price could be as high as $50 per liter. The GE C3T magnet uses only 12 liters of liquid helium. If this magnet were made with the conventional bath cooling, it would require 500 liters of liquid. At the price of $15/liter, the helium savings is > $7 K. When a conventional magnet quenches, almost all the helium will be evaporated and vented. Refill helium costs money and labor. The GE C3T magnet was intentionally quenched during the final test at the research center to ensure the magnet quench will be safe for operators and patient, and magnet will not be damaged due to a quench. After the quenches, no helium was lost. The cooling system automatically cooled the magnet back down and collected liquid helium. No recurring helium cost to the magnet.
Common Sense Emergency Response
Published in Robert A. Burke, Common Sense Emergency Response, 2020
Because they have boiling points of −130°F or colder, all cryogenic liquids are above their boiling points at ambient temperatures. Liquid helium has a boiling point of −452°F below zero; it is the coldest material known. It is also the only material on earth that never exists as a solid, only as a cryogenic liquid and as a gas. Unlike propane and other liquefied gases, gases that are liquefied into cryogenics are liquefied through a process of alternating pressurization, cooling, and ultimate decompression. Therefore, they do not require pressure to keep them in the liquid state. However, if they will be in containers for long periods, they are pressurized to keep them liquefied as long as possible. Nonpressurized cryogenics are kept cold by the temperature of the liquid and the insulation around the tanks.
Assessment of Power System Resiliency with New Intelligent Controller and Energy Storage Systems
Published in Electric Power Components and Systems, 2023
Sariki Murali, Ravi Shankar, Prateek Sharma, Shivam Singh
SMES is a newly discovered storage device that stores electrical energy in the form of a magnetic field generated by a coil. In SMES, a DC current is passed through a coil composed of superconducting material. The coil achieves superconductivity by operating at cryogenic temperatures, thereby minimizing resistive losses. To maintain an extremely low temperature, the coils are submerged in liquid helium. SMES enhances transmission capacity and voltage stability by reducing low-frequency oscillations in the grid. The transfer function of SMES is expressed as follows [42, 46]: