Cryocooler [6]
—Fundamental Review of Cryogenic Refrigerators—

Abstract

Part VI, the final part of this study, covers the multi-stage expansion cycle. The thermodynamic mechanism of the minimum attainable temperature is described by means of a single-stage expansion method. A simplified computer simulation model has been developed for the multi-stage expansion cycle. An example calculation for a two-stage Stirling cooler and GM-type pulse-tube cooler is performed. The effect of real gas properties and specific heat of the regenerator material are discussed, as well as operating conditions such as pressure ratio and frequency. The final section of this study discusses the Vuilleumier cycle, which is not widely utilized in the application field of cryocoolers. In the future, however, this method, in conjunction with a thermo-acoustic resonating system, might have some potential from the viewpoint of long life or low-cost coolers because of its simplicity.