USA: A team of researchers at Louisiana State University are the latest group to claim a breakthrough in research into the magnetocaloric materials used in magnetic cooling.
The team led by LSU physics professor Shane Stadler focuses on the next generation of magnetic cooling technologies which haves potential applications in areas related to energy, electronics and the environment.
In this new technology, a magnetic field magnetically orders the material at ambient temperature, which raises its temperature above ambient. The excess heat is removed through a thermal medium, such as water or air, bringing the material back to ambient temperature. The magnetic field is then removed, the material becomes magnetically disordered and its temperature drops below ambient temperature leading to a cooling effect. This “solid state” cooling process is said to be significantly more energy efficient than the conventional, compressed gas systems currently on the market today.
“We’ve studied these systems for a long time and were fortunate to discover a system in which a magnetic transition coincided in temperature with a structural transition,” Stadler said. “That this magnetostructural transition occurs near room temperature is what makes it a strong candidate for magnetocaloric cooling devices of the future.”
“We are excited about the potential applications that are available for Dr Stadler’s technology,” said Andrew Maas, assistant vice president for research over technology transfer and director of the renamed Office of Innovation and Technology Commercialisation. “The Department of Energy, General Electric and other companies around the world have been working with magnetocaloric materials for some time. Dr Stadler’s solution addresses many of the issues that these big players have encountered.”
The new MnNiSi (manganese-nickel-silicon) materials do not differ greatly from others in this research field but, according to Dr Stadler, there are two main differences. He told the Cooling Post, “They show very large magnetic entropy changes (although over a narrow temperature range), and they are extremely sensitive to applied hydrostatic pressure – essentially, the effect shifts in temperature with applied pressure.”
Seeing a potential for devices in the future to exploit these effects, he added: “Due to the pressure sensitivity, we have high hopes for forthcoming barocaloric measurements. The material shows very little magnetic hysteresis (which is good), but significant thermal hysteresis (not good). So there is still work to be done – including testing in prototypes.”
Currently, a local group of entrepreneurs have expressed interest in this advanced technology. After further testing, they will look into developing commercialisation opportunities utilising it for the heating and cooling industry.
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