Scientists at Brookhaven National Laboratory have made a breakthrough in materials research, which could ultimately lead to magnet powered refrigeration systems.
For most, “refrigerator magnets” are used to stick notes and mementos somewhere prominent. But scientists have known for some time that a peculiar property in some materials can also be used to create a heat pump simply by applying magnetic fields—known as the magnetocaloric effect.
Like any other heat pump, this effect can be used to either raise or lower the temperature in a system. Because it does not rely on fans and pumps, engineers have long been interested in making use of the effect to create more robust, longer-lasting refrigeration systems. General Electric, the company behind the modern refrigeration industry, believes they can raise efficiencies by 20% (or more).
Unfortunately, most of the materials exhibiting the properties of this effect only do so by starting off at extremely low temperatures. The material involved in this study—ytterbium-indium-copper-four, for instance—exhibits the property only in realm of 400 degrees below zero, Fahrenheit.
The key discovery made by the researchers, however, has more to do with understanding the effect. Their discovery is related to the Kondo Effect, an equation describing the behavior of electrons in metal due to magnetic impurities. The scientists believe they have discovered a method that can be used to help tailor that effect, and thus, the behavior of magnetism in certain materials.
This ability to understand the underlying mechanics of magnetocaloric materials will assist engineers in searching for substances in which the effect occurs at closer to room temperature.
GE has already developed a magnetocaloric refrigerator that works by stepping down temperatures some fifty times in small gradients with multi-stage cooling. Developing or discovering materials that could be more finely tuned and operate closer to room temperatures could dramatically simplify this process and bring it one step closer to commercial realization.