| Research on magnetic refrigeration systems has intensified in recent years because of the potential of magnetic refrigerators for greater efficiency, high reliability, and more rugged construction than the present gas cycle refrigerators. This dissertation presents analytical investigation results on magnetic refrigeration systems for hydrogen liquefaction. Second law analysis on a designed three-stage AMR (active magnetic regenerator) hydrogen liquefier is presented. The results show the one cycle cooling capacity and energy loss as the function of material bed volume, material curie temperature, magnetic field strength and helium fluid parameters (pressure, temperature and mass flow rates). Optimization analysis on a designed two-stage AMR hydrogen liquefier was also carried out. Maximizing the liquefier efficiency is performed with respect to changeable variables. The optimization study results show that the liquefier efficiency can be improved by adjusting the interstage temperature, bed length and bed particle size of the two stages. |
