Performance enhancement of hydrogen liquefaction process via absorption refrigeration and organic Rankine cycle-assisted liquid air energy system

This study focuses on the design and analysis of a liquid hydrogen production process integrated with an ab-sorption refrigeration system, a liquid air energy storage system, and an organic Rankine cycle for designing an energy-efficient integrated process. The absorption refrigeration system and liquid air energy storage system facilitate hydrogen pre-cooling, whereas the organic Rankine cycle helps to recover the waste heat generated after air combustion. An ammonia/water-based absorption refrigeration system accompanied by liquid air precools the hydrogen to-180 ?, and the vapor compression refrigeration system liquifies the hydrogen. In this study, an energy-efficient process integration scheme was designed to reduce the overall energy consumption and recover waste heat. The net specific energy consumption of the process was 6.71 kWh/kg. The design variables and composite curve analyses indicate that the most energy-intensive part of the process is the liquefaction section. Moreover, exergy analysis indicates that multi-stream heat exchangers primarily contribute towards exergy destruction. The exergy efficiency of the process was 35.7%. Environmental analysis shows that the refrigeration cycles mainly contribute towards carbon dioxide emissions. Furthermore, according to the economic analysis, compressors and multi-stream heat exchangers accounted for 88.5% of the total capital in-vestment. Overall, these analyses report energy efficient integration and indicate the potential for further improvements, particularly in the refrigeration cycle. This study is expected to provide insights into the design of energy-efficient integrated hydrogen liquefaction processes that exploit the benefits of the absorption refrigeration system, liquid air energy storage system, and organic Rankine cycle.