This paper introduces several liquefaction and refrigeration cycles, such as Linde cycle, Claude cycle, Reverse Stirling cycle and Gifford-MacMahon cycle with the examples of helium machine in foreign countries, and discusses about their characteristics. At present helium machine is in a stage of completion as the industrial and chemical machinery, but from the standpoint of electrical machinery, it is still in a very infant stage. It is necessary to improve its reliability and to solve its maintenance free problems like housefold refrigerators.
In this paper are described basic principles of refrigeration, followed by various refrigeration cycles, classical and modern, with special emphasis on their meanings but without recourse to complicated formulae.
The recent development of large scale refrigerator and liquefier at low temperatures is described. Several typical plants which have already been installed are explained such as a large scale helium liquefiers in helium extraction plants, a tonnage hydrogen liquefier for the Saturn rocket fuel production, and combined refrigeration system of helium and hydrogen for a bubble chamber with a superconducting magnet.