Toward flexible hydrogen supply: Dynamic simulation and control of mixed-refrigerant-precooled liquefaction plants

This study investigates the dynamic behavior of large-scale hydrogen liquefaction plants using mixed-refrigerant (MR) precooling to enhance operational flexibility for renewable energy integration. Hydrogen liquefaction is essential for hydrogen transport but remains energy-intensive. MR-precooled plants can significantly reduce energy consumption; yet, their dynamic performance and control strategies are underexplored. Dynamic simulation is crucial for capturing time-dependent responses to disturbances and designing robust control systems. This work develops the first dynamic simulation and control structure for an MR-precooled hydrogen liquefaction plant producing 100 tpd of liquid hydrogen (LH 2 ). The model is validated against steady-state results and evaluated under variations in feed temperature, pressure, mass flow, and MR compressor power. Results show that the control strategy maintains the LH 2 temperature at 22.5 K, restoring stability within 22 min to 96 min. These findings confirm the feasibility of dynamic control for MR-precooled liquefiers and provide a foundation for future validation with operational data.