A Model for Energy and Exergy Flow in an Orifice Pulse Tube Refrigerator

Abstract

Rational bases for performance evaluation of cryocoolers are second law and exergy analyses. In this study, a model is proposed for the calculation of energy and exergy flow in an Orifice Pulse Tube Refrigerator (OPTR). Using a needle valve, it can be shown that the mass flow rate in the hot side of the OPTR, in general, can be written as a Fourier series expansion. Using the conservation of energy and the balance of exergy for the valve, a general formula for the timed-average irreversibility of the valve is obtained in which the usual, small amplitude approximation is removed. A numerical model is developed to investigate the effect of important system parameters on energy and exergy flow in the pulse tube components. Using the exergy balance on each component, the irreversibility of each component is determined. The goal of this study is to find the effect of important system parameters on the timed-average irreversibility of the distribution of components in the OPTR. It is shown that the regenerator contributes the most to the system irreversibility in a well-designed OPTR. Using the recent empirical relations for pressure drop and a simple model for thermal analysis in the regenerator, the exergy flow and irreversibility of different processes in the regenerator are determined.