Comparison of two models of a double inlet miniature pulse tube refrigerator: Part A thermodynamics

The cooling of electronic components is of great interest to improve their capabilities, especially for CMOS components or infrared sensors. The purpose of this paper is to present the design and the optimization of a miniature double inlet pulse tube refrigerator (DIPTR) dedicated to such applications. Special precautions have to be considered in modeling the global functioning of small scale DIPTR systems and also in estimating the net cooling power. In fact, thermal gradients are greater than those observed in normal scale systems, and moreover, because of the small dimensions of ducts (diameter), the pulse tube cannot be assumed to be adiabatic. Hence thermal heat conduction phenomena must be considered. Besides dead volumes introduced by junctions and capillaries cannot be neglected any more in front of the volume of the gas tube itself. The hydrodynamic and thermal behaviors of the cooler are predicted by means of two different approaches: a classical thermodynamic model and a model based on an electrical analogy. The results of these analysis are tested and criticized by comparing them with experimental data obtained on a small commercial pulse tube refrigerator.