Development of Recuperator for 4 K Pulse Tube Refrigerators Operating at Opposite Phases

Abstract

A 4 K pulse tube refrigerator can be constructed with a recuperator as the second stage regenerator and two pulse tubes operating at opposite phases in the second stage. The recuperator would be the critical component in this configuration, as is the second stage regenerator in typical 4 K cryocoolers. The required condition of this recuperative pulse tube refrigerator for efficient performance is that the recuperator should excel or at least equal the typical second stage regenerator. The recuperator has to have lower pressure drop, lager heat transfer area and smaller void volume. Practically the major difficulty encountered in adapting the recuperator to pulse tube refrigerator is the fact that small void volume is not easily achieved in the recuperator. In order to fulfill such requirement, the recuperator has to be constructed with very narrow channels. The way of constructing narrow channels which is recommended in this paper is forming the metal sheet-porous spacer-metal sheet layers. If the recuperator is constructed in the recommend way in the flat rectangular form, the configuration of placing ports at the four corners with the flow across is revealed to have the optimal performance.