The prospect of the phase-out of cloroflurocarbons suggests that alternative refrigeration technologies be sought. One of them, magnetic refrigeration, is potentially a highly efficient and high power density technology because the magnetic process on which it is based is essentially reversible and the volumetric heat capacity of the refrigerant is very high. This project will develop a new generation of high efficiency magnetic refrigeration systems based on Gd₅(SiGe)₄ intermetallics with a giant magnetocaloric effect. The intermetallics will be formed into novel polycapillary materials to produce refrigerant beds with operational efficiencies up to 30% greater than existing beds made of packed intermetallic powder. Phase I concentrated on processing Gd₅(SiGe)₄ into a microchannel bed configuration. The basic requirements for the source materials and fabrication processes were established. The initial characterization of the produced beds was performed in terms of phase composition, structure, and magnetic properties. Phase II will optimize and scale up the fabrication technology for Gd₅(SiGe)₄ powders, and polycapillary materials made out of them, to produce active microchannel magnetic refrigerant beds. The beds will be manufactured and tested in active refrigeration systems.

Commercial Applications and Other Benefits as described by the awardee. Potential applications include but are not limited to: production of superfluid helium, comfort air conditioning, refrigerators for cooling high temperature superconductor devices such as magnetic energy systems, motors, generators, and one-ton-per-day high efficiency hydrogen liquifiers.