Design and analysis of LNG cold energy utilization system combining hydrogen liquefaction and power output

The integration of hydrogen liquefaction with power output represents a forward-looking approach in the context of liquefied natural gas (LNG) gasification processes. This study proposes a system that incorporates a double cascade organic Rankine cycle (ORC) and an enhanced deep-cooling liquefaction cycle to optimize cold energy utilization and efficiency during the hydrogen cryogenic cooling stage. Additionally, the optimization process employs both the particle swarm optimization algorithm (PSO) and the non-dominated sorting genetic algorithm (NSGA-II). The findings indicate that NSGA-II outperforms PSO, achieving an exergy efficiency of 61.01 %, a net ORC output power of 1584 kW, and a specific energy consumption of 6.67 kWh/kg_H2. Economic and exergy analyses undertaken to evaluate and contrast the conventional system with the proposed one. The results demonstrate a cost savings of 8.2 % in the improved system, accompanied by a decrease in the helium mass flow rate from 18.51 kg/s to 12.65 kg/s. This study aims to offer theoretical support for refrigeration cycles in the hydrogen liquefaction stage and LNG gasification processes.