Progress and challenges in utilization of ejectors for cryogenic cooling

In the field of cryogenic cooling, Joule–Thomson (JT) cooling is a mature technology but suffers from low efficiency. Various efforts such as the optimization of compressors, cold stages, working fluids, and operating conditions have been reported to develop more efficient JT cooling systems. As a further alternative, ejectors can be used in JT cooling systems to create sub-atmospheric pressures and to recover expansion work, and thus achieve lower temperatures and higher system efficiency. This paper presents a comprehensive review of the use of ejectors for cryogenic cooling. The research progress of cooling cycles with ejectors at the system-scale is analyzed and compared, followed by the experimental investigation and numerical simulation of ejector performance at the component-scale. The experimental studies mainly discuss the local flow characteristics of ejectors captured through pressure measurements and flow visualization. The simulation studies introduce the analytical modelling of ejectors although the focus is on the CFD modelling. Current challenges and suggestions for future research on the use of ejectors in cryogenic cooling systems are summarized.