Design and optimization of cryogenic supercritical hydrogen storage system coupled with mixed refrigerant and gas expansion cycle

Abstract

Cryogenic supercritical hydrogen, as a physical hydrogen storage method, is used to increase the volume and weight of hydrogen storage density without phase change by means of a combination of cooling and pressurization. In this study, a cryogenic supercritical hydrogen storage system coupled with mixed refrigerant and gas expansion cycle is proposed for the cryogenic supercritical hydrogen cooling thermodynamic process. The cryogenic supercritical hydrogen storage system proposed in this paper can compress and cool hydrogen at ambient temperature and pressure to 70 K and 30 MPa, and the hydrogen storage density at this state point is 72.53 kg/m3. Aspen HYSYS software is used to simulate and analyze the system process, and 29 key variables in the system are optimized by genetic algorithm with specific energy consumption (SEC) as the objective function. The system performance is analyzed by varying the expansion refrigeration cycle work gases, and helium, hydrogen and neon are selected for horizontal comparison, and the energy, exergy and heat transfer performance of the three gases are analyzed in detail at the end of the optimization. The results show that neon has the best performance as the expansion cycle working medium, with the SEC of5.87 kWh/kgH2.The theoretical minimum SEC is 2.92 kWh/kgH2 and the exergy efficiency (EXE) is 49.74 %.