Conceptual design and optimization of a novel hydrogen liquefaction process based on helium expansion cycle integrating with mixed refrigerant pre-cooling

Abstract

Due to the safety of operation and the development of high-efficiency helium refrigerators, the development of helium refrigeration cycles in hydrogen liquefaction is continuously promoted. To reduce the energy consumption and exergy loss of this energy-intensive process, a novel hydrogen liquefaction process integrating with mixed refrigerant (MR) pre-cooling is simulated by Aspen HYSYS and optimized by genetic algorithm (GA) to improve performance under the premise of safe production and multi-faceted analyzed based on the helium expansion refrigeration cycle. A new MR with reasonable composition and ratio is used in the pre-cooling cycle to improve the matching of heat transfer curves. Energy, exergy and economic analyses are applied to evaluate the liquefaction process, and horizontal comparison is also used to evaluate the rationality and superiority of the process design. The output of 5 t/d of liquid hydrogen (21.7 K, 1.5 bar) can be achieved and the overall specific energy consumption (SEC), exergy efficiency (EXE) and coefficient of performance (COP) are 9.703 kWh/kg LH2, 39.1%, and 0.1333, respectively. Compared with similar processes, the proposed process shows better performance and potential development prospects.