Introducing and energy analysis of a novel cryogenic hydrogen liquefaction process configuration

A novel efficient hydrogen liquefaction process is introduced and analyzed. Two independent refrigeration cycles with different mixed refrigerants (MR) are used in the process which can produce 300 tons liquid hydrogen per day. The proposed process liquefies a feed of 3.450 kg s^‑1 normal hydrogen gaseous at 25 °C and 21 bar to equilibrium temperature (‑195 °C) by the first refrigeration cycle with power consumption of 1.102 kWh/kgLH2. In the second refrigeration cycle, the hydrogen is cooled to ‑253 °C with power consumption of 3.258 kWh/kgLH2, enjoying the least total power consumption compared to the identical liquefaction plants. Thermal design of the heat exchangers and expanders at wide range of temperature and using innovative and appropriate mixed refrigerants according to the configuration are novel aspects of the proposed process. Also, composition of the first and second refrigeration cycles' refrigerants is another novelty of the proposed process. Energy and exergy analyses of the proposed process are investigated. The energy analysis reveals that coefficient of performance of the proposed process is 0.1797 which is considerably higher than the other identical processes. According to the results of the exergy analysis, exergy efficiency of the first refrigeration cycle, second refrigeration cycle and the whole liquefaction process are 67.53%, 52.24% and 55.47%, respectively.