The small, highly efficient, thermal regenerators used in cryogenic refrigerators present a very complex problem in analysis and design. Many effects which are negligible in larger, less efficient, regenerators produce sizable thermal losses in these small units and must be considered if their performance is to be calculated accurately. Included among these are longitudinal heat conduction, temperature-dependent property variations, surface, feed gas flow, and end effects. This paper describes these effects and presents the results of an analytical and experimental investigation conducted to determine the magnitude and physical nature of the resulting thermal losses. Included also is a description of the mathematical parallel flow analogy that was used to overcome the poor computational time accuracy characteristics of the finite difference method used to calculate regenerator performance.
A spectral method for numerical modeling of radial microwave heating in cylindrical samples with temperature dependent dielectric properties