Helium magnetic refrigerator. II. Liquefaction process and efficiency

Magnetic refrigeration techniques are based on the utilization of the magnetocaloric effect. A change in entropy occurring as a result of a change in magnetization leads to heat-transfer processes. The magnetic refrigerator consists of two parts, including the magnetic materials and the heat-exchange system. Advantages of this type of refrigerator compared to the gas refrigerator are related to high efficiency, compactness, and high reliability. The present investigation is concerned with a new Carnot type refrigeration system which liquefies helium with the aid of Gd3Ga5O12 (GGG) as a refrigerant. Attention is given to the heat transfer between GGG and helium gas, the experimental apparatus, and the obtained experimental results. 7 references