  One of the key issues in magnetic refrigeration is generating the magnetic
field that the magnetocaloric material must be subjected to. The magnet
constitutes a major part of the expense of a complete magnetic refrigeration
system and a large effort should therefore be invested in improving the magnet
design. A detailed analysis of the efficiency of different published permanent
magnet designs used in magnetic refrigeration applications is presented in this
paper. Each design is analyzed based on the generated magnetic flux density,
the volume of the region where this flux is generated and the amount of magnet
material used. This is done by characterizing each design by a figure of merit
magnet design efficiency parameter, $\Lambda_\mathrm{cool}$. The designs are
then compared and the best design found. Finally recommendations for designing
the ideal magnet design are presented based on the analysis of the reviewed
designs.
