Process development and exergy cost sensitivity analysis of a novel hydrogen liquefaction process

A novel hydrogen liquefaction process including a single mixed refrigerant cycle is proposed and investigated by energy, conventional and advanced exergy and exergoeconomic analyses methods. The proposed liquefaction process can produce 130 tons liquid hydrogen per day. Results of energy analysis reveals that 7.646kWh/kgLH2 power is consumed to liquefy the hydrogen from 21 bar to 25 °C. Exergy analysis indicates that exergy efficiency of the proposed hydrogen liquefaction process is almost 32%, which is higher than Ingolstadt operating hydrogen liquefaction plant with exergy efficiency of 21.28%. Also, the power consumption of proposed hydrogen liquefaction plant is less than its kind between other similar conceptual processes. Based on the advanced exergy analysis, most part of the exergy destruction rates of the compressors, heat exchangers and air cooler are endogenous, while the dominant part of irreversibilities of the turbo expanders is exogenous. Effect of mole fraction of the mixed refrigerant components on performance of the process is investigated. Also, sensitivity of exergy destruction cost rate and exergoeconomic factor to operating variables of the proposed hydrogen liquefaction process is investigated and discussed. Results of the analyses show that maximum exergy destruction cost rate of the process components is 2265.26 $/h, which most of it is endogenous and unavoidable.