Progress and challenges in utilization of ejectors for cryogenic cooling

Strategies to recover and minimize boil-off losses during liquid hydrogen storage

“…Since the boiling temperature of LN 2 is higher than that of LH 2 (77 K vs. 20 K), the primary purpose of nitrogen is to pre-cool H 2 below its J-T inversion temperature (200 K at atmospheric pressure) so that the H 2 can be expanded later via a J-T valve [65]. The J-T inversion temperature is defined as the point at which the J-T coefficient ( ) becomes zero, indicating that an isenthalpic pressure drop no longer produces a change in temperature [92]. Any fluid expanding through a J-T valve will only cool down if it is below its J-T inversion temperature; otherwise, it will warm up.…”

“…Ejectors have emerged as useful devices for achieving high-efficiency refrigeration cycles in the liquefaction of liquid H 2 compared to conventional Claude, Linde or reverse Brayton cycles. An ejector is a work-producing device without moving parts that can enhance the efficiency of the refrigeration cycle by utilizing the high-pressure gas leaving the compressor to increase the cooling capacity of the refrigeration system [92,95]. Ejectors have a wide range of applications, including as jet pumps or compressors [92].…”

Two-stage cascade configurations based on ejectors for ultra-low temperature refrigeration with natural refrigerants

“…However, the influence of the ejector in two-stage cascades for ULT refrigeration has yet to be considered. Cao and Brake [22] observed that, unlike most refrigeration applications, ejectors at low temperatures are scarce, with a few works focusing on concept design, experimental investigation, and thermodynamic analysis. After reviewing different types of cascade refrigeration systems for ULT application, Kasi and Cheralathan [23] recommended configurations including an ejector.…”

Experimental Study on a Multi-Evaporator Refrigeration System Equipped with EEV-Based Ejector

“…An ejector is a simple component that can mix two different pressure fluids and elevate the pressure of the mixed fluid without using mechanical energy [ 6 ]. In 1910, Leblanc designed an ejector-based refrigeration system [ 7 ]. Gay [ 8 ] presented a two-phase ejector instead of the traditional expansive valve to increase the system performance by reducing the throttling loss.…”