14 DAY TRIAL // When refrigerators first started making their way into the homes of average people, around the first third of the 20th century, they created a true revolution. Food could then be kept frozen for a long time, and people no longer had to rely on ice suppliers to get their cooling sources. With these devices, along with air-conditioning machines, humans experienced a massive change in the way they lived their life, and women of the time stopped spending most of it in the kitchen. A similar revolution could take place soon as well, if experts manage to devise a working prototype for a new class of devices – magnetic refrigerators and air conditioners.
Modern-day fridges work on the basic principle of gas compression, and thus require large amounts of electricity to operate. The same applies to air conditioners, which require a great amount of current to reduce or increase temperature. But a new class of refrigerating devices may soon replace them, one that would require 20 to 30 percent less electricity, and would operate without ozone-depleting chemicals or other greenhouse gases. In short, the new machines could work on the principle of magnetic refrigeration.
This means that the instruments would no longer use gas compressors to generate cold air inside them, but that they would virtually surround a layer of magnetic materials (most likely metallic alloys) with a strong magnetic field. Applying such a magnetic field would undoubtedly heat the material, which would then be cooled using nothing but water. Once the metallic alloys reach their average temperature, the magnetic field is removed, which generates a further cooling reaction in the alloys. Experts at the Imperial College London (ICL) are currently working on ways of refining these processes for commercial applications.
“We found that the structure of crystals in different metals directly affects how dramatically they heat up and cool down when a magnetic field is applied and removed. This is an exciting discovery, because it means we may one day be able to tailor-make a material from the 'bottom up,' starting with the microstructure, so it ticks all the boxes required to run a magnetic fridge. This is vitally important because finding a low-energy alternative to the fridges and air conditioning systems in our homes and work places is vital for cutting our carbon emissions and tackling climate change,” ICL Department of Phsyics Professor Lesley Cohen said.
Cohen has been one of the authors of a new scientific paper detailing the technique, published in last month's issue of the journal Physical Review B. Funds for the new research were provided by the Engineering and Physical Sciences Research Council (EPSRC). The results revealed that it was, in fact, the crystalline structure inside the metal alloys – their microstructure – that gave the materials the properties scientists were searching for.