Cascade JT systems with single-component refrigerants for hydrogen liquefaction

• Published in: Cryogenics (Guildford) 2022-01, Vol.121, p.103410, Article 103410
• Main Authors: Chang, Ho-Myung, Park, Min Gyun
• Format: Article
• Language: English
• Subjects: Ammonia; Argon; Cascade system; Cryogenic temperature; Figure of merit; Hydrogen liquefaction; JT cycle; Liquefaction; Liquefied natural gas; Neon; Performance indices; Refrigerants; Single-component refrigerant; System effectiveness; Working fluids
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2021.103410

•Hydrogen liquefaction systems without cryogenic expander are investigated.•Cascade JT systems with single-component refrigerants are suitable for large-scale liquefaction.•Modified Linde-Hampson systems with a variety of pre-cooling cycles are optimized.•A reasonably high efficiency can be achieved with the optimized cascade JT systems. A thermodynamic study is carried out for hydrogen liquefaction with cascade Joule-Thomson (JT) systems, which do not require any expansion machines. Since there is no moving part at cryogenic temperatures, the cascade JT systems have a potential advantage of high reliability and easy scale-up of liquefaction capacity, as demonstrated in the full-scale LNG plants under operation. A variety of combinations for pre-cooling JT cycles with single-component refrigerants (including neon, nitrogen, argon, oxygen, hydrocarbons, and ammonia) are investigated to estimate the figure of merit (FOM) as a performance index of liquefaction. In every JT cycle, the pressure levels are optimized to maximize the FOM with a process simulator (Aspen HYSYS) and real properties of working fluids (NIST REFPROP). It is rigorously shown that the cascade JT systems can achieve a reasonably high FOM, if the irreversibility below 77 K is effectively reduced. A few suitable cascade systems for large-capacity hydrogen liquefaction are identified, and the details of optimized cycles are presented.