Commercial Development
This refrigeration, once proven viable, could be used in any possible application where cooling, heating or power generation is used today. Since it is only at an early stage of development, there are several technical and efficiency issues that should be analyzed. The magnetocaloric refrigeration system is composed of pumps, electric motors, secondary fluids, heat exchangers of different types, magnets and magnetic materials. These processes are greatly affected by irreversibilities and should be adequately considered.
Appliances using this method could have a smaller environmental impact if the method is perfected and replaces hydrofluorocarbon (HFCs) refrigerators (some refrigerators still use HFCs which have considerable effect on the ozone layer. At present, however, the superconducting magnets that are used in the process have to themselves be cooled down to the temperature of liquid nitrogen, or with even colder, and relatively expensive, liquid helium. Considering these fluids have boiling points of 77.36 K and 4.22 K respectively, the technology is clearly not cost- and energy-efficient for home appliances, but for experimental, laboratory, and industrial use only.
Recent research on materials that exhibit a large entropy change showed that alloys are some of the most promising substitutes of gadolinium and its alloys — GdDy, GdTb, etc. Gadolinium and its alloys are the best material available today for magnetic refrigeration near room temperature. There are still some thermal and magnetic hysteresis problems to be solved for them to become truly useful and scientists are working hard to achieve this goal. Thermal hysteresis problems is solved therefore in adding ferrite (5:4).
Research and a demonstration proof of concept in 2001 succeeded in applying commercial-grade materials and permanent magnets at room temperatures to construct a magnetocaloric refrigerator which promises wide use.
This technique has been used for many years in cryogenic systems for producing further cooling in systems already cooled to temperatures of 4 K and lower. In England, a company called Cambridge Magnetic Refrigeration produces cryogenic systems based on the magnetocaloric effect.
On August 20, 2007, the Risø National Laboratory (Denmark) at the Technical University of Denmark, claimed to have reached a milestone in their magnetic cooling research when they reported a temperature span of 8.7 C. They hope to introduce the first commercial applications of the technology by 2010.
Read more about this topic: Magnetic Refrigeration
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