Volume 46: Energy Transitions toward Carbon Neutrality: Part IX

Design and analysis of a novel liquid hydrogen production system using dual mixed refrigerant-based cryogenic precooling and liquefaction processes Ahmad K. Sleiti, Wahib A. Al-Ammari



This study presents an innovative LH2 productionsystem using dual mixed refrigerant (DMR)-basedcryogenic processes. New dual-refrigeration loops aredeveloped for the precooling and liquefaction of thegaseous hydrogen with two distinguished mixed refrigerants for each process. Thorough energy, exergy, economic, and environmental (4E) analyses are conducted for the proposed LH2 system in this study. The proposed system produces LH2 with an energy consumption of 3.732 kWh/kgLH2, 48% lower than the single mixed refrigerant SMR-based systems and 70% lower than the current commercial plants. Furthermore, the exergy efficiency (59.65%) of the present system is enhanced by 33% compared to the SMR-based systems (44.89). In addition, the present system produces LH2 with a levelized cost of 1.89 $/kgLH2, which is 21% lower than that for SMR-based large-scale systems and 70% lower than that of small-scale systems. Environmentally, the proposed DMR-LH2 system reduced CO2 emissions by 29-69% compared to large-scale SMR-based systems. Moreover, the DMR-LH2 system is characterized by more flexibility in the design of the process equipment and eliminates the potential for freezing problems. This study’s dual mixed cryogenic refrigeration approach provides guidelines for future research to improve the technical and economic feasibility of LH2 production, making it competitive with other energy storage and transportation options.

Keywords liquid hydrogen, cryogenic refrigeration, mixed refrigerants, SEC, LCOH, 4E analyses

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