Thermoeconomic analysis of novel hydrogen liquefaction assisted by absorption refrigeration utilizing heat from Brayton cycle

Abstract

Current research presents a novel method for reducing the energy consumption of hydrogen liquefaction through heat recovery of hydrogen liquefier. An ammonia absorption refrigeration cycle on the hydrogen precooling utilizes the heat generated by the compressor intercooler and aftercooler of the reverse Brayton cycle of hydrogen liquefier to precool hydrogen feedstock. The system is analyzed from exergy, energy, and economic perspective. The results are compared with the reference case without a heat recovery system. The proposed system can reduce SEC (specific energy consumption) from 7.37 kWh/kgLH2 to 6.23 kWh/kgLH2 and exergy efficiency improvement from 55.2% to 60.90%. The economic analysis shows that the levelized cost of energy to produce 5.07 tons/day of liquid hydrogen for the reference and novel case is 5.88 USD/kgLH2 and 5.03 USD/kgLH2, respectively. The results imply that the proposed method can be a reference for designing an integrated hydrogen liquefaction system to minimize energy consumption.