Fridge magnet technology to herald eco-friendly coolers

Magnetic refrigeration technology could provide a 'green' alternative to traditional energy-guzzling gas-compression fridges and air conditioners – according to research conducted by Imperial College.

According to research, published in Advanced Materials, they would require 20 to 30 percent less energy to run than the best systems currently available, and would not rely on ozone-depleting chemicals or greenhouse gases.

The lead scientist, Kelly Morrison, found that at the molecular level two different temperature change processes, known as first- and second-order changes, happen simultaneously in each material.

Her team believes that the extent to which each of these two processes feature in a material also affects its cooling capabilities.

Refrigeration and air conditioning units make a major contribution to the planet's energy consumption.

A magnetic refrigeration system works by applying a magnetic field to a magnetic material - some of the most promising being metallic alloys - causing it to heat up.

This excess heat is removed from the system by water, cooling the material back down to its original temperature. When the magnetic field is removed the material cools down even further, and it is this cooling property that researchers hope to harness for a wide variety of cooling applications.

The technology has proved possible in the lab but researchers are still looking for improved materials that provide highly efficient cooling at normal room temperatures, so that the technology can be rolled out from the lab to people's homes and businesses.

They need a material that exhibits dramatic heating and cooling when a magnetic field is applied and removed, which can operate in normal everyday conditions, and which does not lose efficiency when the cooling cycle is repeated time after time.

The new study published on Friday shows that the pattern of crystals inside different alloys - otherwise known as their microstructure - has a direct effect on how well they could perform at the heart of a magnetic fridge.

The Imperial College London team behind the new findings say this could, in the future, help them to custom-design the best material used in refrigerator manufacture.

"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,” said professor Lesley Cohen.

“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," added Cohen.

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