1. Required energy to compress the hydrogen gas at 70MPa is about 15% of HHV, 21MJ/kg. Minimum work for hydrogen liquefaction is 12MJ/kg, so we can estimate the FOM as 12/21=0.57.
2. Research of magnetic refrigeration cycle for hydrogen liquefaction;Utaki;Cryocooler,2007
3. Development of a magnetic refrigerator for hydrogen liquefaction;Numazawa;AIP Conf Proc,2008
4. Hydrogen liquefaction by magnetic refrigeration;Kamiya;Cryocoolers,2007
5. Experimental investigation of two-stage active magnetic regenerative refrigerator operating between 77K and 20K;Kim;Cryogenics,2013