Further experimental work in mixed gas Joule-Thomson cryocooling

Abstract

Abstract Miniature Joule-Thomson (JT) cryocoolers are attractive for many applications due to their small size and resulting fast cool-down time. Finned-tube heat exchangers are one of the most widely used heat exchanger for miniature JT cryocoolers. The basic configuration, known as a Giauque-Hampson (GH) or coiled tube heat exchanger, involves the high-pressure stream flowing through a finned-tube that is helically coiled upon a cylindrical core while the low-pressure return stream flows over the fins in the annular space created by the core and the inner diameter of a shell. The experimental work in this study aimed to gain insight into thermal characteristics of the shell-side of a GH heat exchanger by developing a test facility capable of measuring the two-phase heat transfer coefficient (htc) for this flow at operating conditions of interest to mixed-gas JT (MGJT) cryocooling. The capabilities of the test facility were demonstrated and measurements of the two-phase htc of the mixed gas on the shell-side of the GH heat exchanger prototype revealed that the shell side is the dominant thermal resistance for these operating conditions, even though the fins provide a larger surface area.