Comparative investigation of low and high frequency pulse tube regenerators

The objective of the present work is to compare the performance of the regenerator of pulse tube refrigerators at low and high frequencies. The hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one-dimensional, periodic, unsteady, compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. The method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net energy flow and entropy generation minimization techniques are applied, in order to calculate the regenerator first and second law efficiencies. The effects of geometry and operating key parameters on the regenerator performance are considered as well.