Researchers at the Technische Universitat (TU) Darmstadt and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) developed a refrigeration technology that uses magnetic materials in magnetic fields.
Dr. Tino Gottschal, research scholar at the HZDR’s Dresden High Magnetic Field Laboratory (HLD), and his colleagues extensively studied different shape-memory alloys and their properties. In the process the physicist discovered that changes in magnetic field modifies the properties of alloys and externally applied pressure can reverse the magnetization process, causing the alloy to heat up. The researchers based the cooling cycle on the ‘magnetic memory’ of special alloys. Successful initial experiments of the alloys based on magnetic memory have been published in the journal Nature Materials, on September 2018.
The team used an alloy of nickel, manganese, and indium for experimentations as these alloys could be converted at room temperature. They employed strongest permanent magnets comprising the rare-earth metal neodymium in addition to iron and boron, to generate magnetic field. The researchers analyzed the property of the alloy with six-step cycle experimentation.
Oliver Gutfleisch, Professor of Functional Materials at the TU Darmstad said: “In the case of reversible magnetization, the cooling effect only lasts as long as the cooling element is exposed to the magnetic field. Even in the best-case scenario, half of the coolant must be placed between the magnets. This means that you need four times as much permanent magnet as cooling medium.”
The project received ERC Advanced Grant from the European Research Council worth a total of 2.5 million euros over five years. The researchers believe that shape-memory alloys will be used for various systems involving cooling cycles.