Finite heat-capacity effects in regenerators

This paper deals with the influence the finite heat capacity of the matrix of regenerators on the performance of cryocoolers. The dynamics of the various parameters is treated in the harmonic approximation focussing on the finite heat-capacity effects, real-gas effects, and heat conduction. It is assumed that the flow resistance is zero, that the heat contact between the gas and the matrix is perfect, and that there is no mass storage in the matrix. Based on an energy-flow analysis, the limiting temperature, temperature profiles in the regenerator, and cooling powers are calculated. The discussion refers to pulse-tube refrigerators, but it is equally relevant for Stirling coolers and GM-coolers.

► The consequences of the finite heat capacity of the regenerator matrix are treated.
► It is shown how the various system parameters affect the COP.
► The finite heat capacity can set a lower limit to the temperature.
► The finite heat-capacity and real-gas effect increase the heat-conduction losses.