Cryogenic supercritical hydrogen storage: Design and thermodynamic optimization via multi-stage Joule-Brayton refrigeration cycles

Abstract

Cryogenic supercritical hydrogen storage emerges as a novel methodology that combines pressurized cooling to achieve storage densities surpassing conventional compressed gaseous systems while circumventing phase-change complexities inherent to liquid hydrogen storage. This study proposes two cryogenic supercritical hydrogen storage systems employing cascaded Joule-Brayton refrigeration cycles, configured with four-stage and five-stage architectures respectively. The optimized systems attain hydrogen storage conditions of 18 MPa at 50 K, achieving a density of 64.64 kg/m³ that closely approaches liquid hydrogen benchmarks. A refrigerant cascade comprising propane, ethylene, methane, nitrogen, and hydrogen enables progressive cooling through expansion processes. System simulations were conducted in Aspen HYSYS® with thermodynamic optimization via genetic algorithm (GA), effectively minimizing specific energy consumption (SEC). Post-optimization energy, exergy, and heat transfer analyses demonstrate superior performance in the five-stage system, exhibiting an SEC of 5.25 kWh/kg_H2 and exergy efficiency (EXE) of 55.3 %, compared to the four-stage system's 5.49 kWh/kg_H2 and 52.9 %. The results substantiate that cryogenic supercritical hydrogen storage can simultaneously achieve high density and low energy expenditure, with the proposed configurations offering viable pathways for next-generation hydrogen storage infrastructure development.