In an efficient Stirling-cycle cryocooler, the cold piston or displacer recovers power from the gas. This power is dissipated into heat in the orifice of an orifice pulse tube refrigerator, decreasing system efficiency. Recovery of some of this power in a pulse tube refrigerator, without sacrificing the simplicity and reliability inherent in a system with no cold moving parts, is described in this paper. In one method of such power recovery, the hot ends of both the regenerator and the pulse tube are connected to the front of the piston driving the refrigerator. Experimental data is presented demonstrating this method using a thermoacoustic driver instead of a piston driver. Control of time-averaged mass flux through the refrigerator is crucial to this power recovery, lest the refrigerator’s cooling power be overwhelmed by a room-temperature mass flux. Two methods are demonstrated for control of mass flux: a barrier method, and a hydrodynamic method based on turbulent irreversible flow. At −55 °C, the ref...

Acoustic recovery of lost power in pulse tube refrigerators

A simple harmonic analysis of the performance of regenerators is described. Computer calculations based on the simple harmonic analysis run orders of magnitude faster than time-integration methods, with acceptably small reductions in accuracy. This simple harmonic analysis method is based on previous one-dimensional differential equations of heat and mass flow, with the additional assumption of steadystate operation and with the key approximations that only the magnitudes and phases of the fundamental components of time-dependent variables are of interest and that the instantaneous friction-factor and heat transfer coefficients are determined from the instantaneous velocity via steady-flow correlations. This permits a rapid computation scheme in which complex amplitudes of oscillatory variables are used, without numerical time integrations. The method is presented here using the Kays and London correlations for stacked-screen regenerators, but it can be used for any regenerator matrix for which steady friction-factor and heat transfer correlations exist.

Simple harmonic analysis of regenerators

Performance of a prototype Stirling domestic refrigerator

This paper is a synthesis of the state of the art in the design and theory of regenerative Pulse Tube cryogenic systems. A general outlook of the functional principles and of the processes occurring in these cryogenic systems is given. The main irreversibility sources are analyzed. A review of the important contributions on the subject, likely to improve the constructional and functional characteristics, is then presented, along with the evaluation of their scientific foundation.

C.W. Lu

Papers

Linear network analysis of regenerator in a cyclic-flow system

Split-type free-displacer Stirling refrigerator design using linear network analysis

Dynamic response of regenerator in cyclic flow system

Linear network analysis of split-type stirling refrigerator