Optimization and analysis of a novel 30 TPD hydrogen liquefaction system with a two-phase hydrogen turbo-expander

Hydrogen liquefaction has aroused substantial attention because of various applications in hydrogen storage and transportation. A hydrogen liquefaction system employing tetra-path circulating hydrogen refrigeration is proposed with a two-phase hydrogen turbo-expander. The system is established in Aspen HYSYS and optimized through genetic algorithm. The results show that when the liquid fraction at the last turbo-expander outlet increases from 0 to 15.5 %, the refrigerant volume flow rate flowing into the proposed system cold box is reduced by 43.2 %, which will contribute to decreasing the size of the cold box within hydrogen liquefaction systems. The sensitivity and exergy analysis are conducted to evaluate the liquefaction performance. The specific energy consumption (SEC), coefficient of performance (COP), and exergy efficiency (EXE) of the system with a liquid fraction of 15.5 % at the two-phase hydrogen turbo-expander outlet are 10.03 kWh·kg_LH2^-1, 13.14 %, and 34.65 %, respectively. The system has superior performance compared with similar systems.