Thermal analysis of 4 K J-T cryocooler equipped with an ejector

Abstract

This paper introduces a 4 K Helium Joule-Thomson (J-T) refrigeration system equipped with ejector technology to enhance thermodynamic efficiency, reduce the lowest cold head temperature, and avoid higher compressor suction pressure. The J-T cryocooler, pre-cooled by a Stirling cryocooler, typically requires a high compression ratio when operating at 4 K or below. The ejector serves as a device that converts pressure energy into kinetic energy, enabling it to draw in secondary fluid and then reconvert kinetic energy into pressure energy, thus increasing the pressure of the low-pressure fluid. To investigate the impact of the ejector on J-T refrigerator performance, this study employs a one-dimensional theoretical calculation. The results are used to establish a performance chart of the J-T refrigeration system with an ejector, which is compared to the system without an ejector. The analysis reveals a promising 10-20% improvement in performance with the ejector technology implemented.