Cryocooler (3)-Fundamental Review of Cryogenic Refrigerators-

Part III of this study covers the basic characteristics of a Stirling cooler based on a simplified Stirling cycle. Two different types of Stirling coolers—one with a piston and displacer, and the other with two-pistons—are described by a simplified isothermal model using Schmidt equations. Examples of calculation results are given to explain the optimum phase difference between the piston movement and the pressure wave of the working gas. The regenerator, as one of the critical components of cryocoolers, is analyzed in detail. Numerical investigations have been conducted to study the regenerator efficiency in terms of the geometry, materials selection, pressure ratio, and the phase between mass flow and pressure in the regenerator. Improvement in regenerator performance is discussed as related to minimization of the enthalpy flow within the regenerator.