Pulse tube refrigeration–a new type of cryocooler

Abstract

A variation of the Stirling cryocooler, known as a pulse tube refrigerator, requires only one moving part- a pressure wave generator at room temperature. The Stirling cryocooler requires in addition a moving displacer at low temperatures to cause a phase shift between pressure and mass flow rate that leads to a refrigeration effect. This paper generalizes the Stirling cycle and shows how instantaneous heattransfer or flow through an orifice can cause a similar phase shift without a moving displacer. Temperatures as low as 60 K have been achieved in a one-stage device where an orifice is used for the phase shifting. The heat transfer mechanism for phase shifting does not yield as low a temperature, but itis semireversible and was used by Wheatley to convert heat energy to acoustic energy, which in turn drove a thermoacoustic refrigerator with no moving parts. This paper compares various pulse tube refrigerators and the Stirling refrigerator using a newly developed enthalpy flow model. Some generalizations of these concepts to systems other than gas systems are made. © The Japan Society of Applied Physics.