The photo is sourced from elektroportal.ru
As a rule, cooling systems used in air conditioners and refrigerators operate on the basis of compressor cooling: temperature decreases due to refrigerants – substances (usually gases) that take away the heat from the object that needs to be cooled when they evaporate. However, at elevated temperatures, like when a refrigerator is being defrosted, refrigerants release toxic compounds, including fluorine and hydrogen chloride.
A greener alternative is magnetic cooling, during which a solid substance changes its temperature in response to the magnetic field surrounding it. If an object is placed in a gradually increasing magnetic field, the substance will begin to cool down and absorb heat from the environment. Alternately, when the magnetic field decreases, the object will release heat and become warmer. Magnetic cooling also operates in a wider temperature range, including temperatures close to absolute zero (minus 273.15 degrees Celsius), whereas a conventional refrigerator operates in the range from plus 4 to minus 20 degrees Celsius. This is why scientists are actively searching for materials that would be particularly effective in terms of magnetic cooling.
One such material has been proposed by the scientists from the Amirkhanov Institute of Physics of the Dagestan Federal Research Centre RAS, who studied the ability of an alloy based on nickel, manganese, tin and a small amount of copper to change its temperature under the influence of a magnetic field. The authors conducted an experiment, in which they placed the alloy in a device, to which constant and pulsed magnetic fields were applied. To assess the magnetic properties of the alloy under study, the scientists changed the temperature in the device within the range from minus 25 to plus 50 degrees Celsius.
The greatest effect was achieved at a device temperature of 1.85 degrees Celsius: under these conditions, the magnetic field’s impact on the alloy made it possible to reduce its temperature by 13.15 degrees Celsius. At the moment of exposure to the magnetic field, the sample was isolated from the environment and could not exchange heat with it. After the magnetic field was turned off, the alloy maintained a low temperature (minus 11 degrees Celsius). This means that the new alloy can potentially be used in hybrid cooling systems that combine the compressor and magnetic methods.
“The proposed method makes it possible to cool down objects by minus 13 degrees Celsius in just 0.1 seconds. As a point of comparison, it takes an average of 1 minute to cool down a gas refrigerant-based refrigerator by 1.8 degrees Celsius. Therefore, magnetic cooling demonstrates more efficient results. The data obtained will be useful in the development of hybrid cooling systems, such as household refrigerators,” Adler Gamzatov, leading researcher at the Amirkhanov Institute of Physics of the Dagestan Federal Research Centre RAS, is quoted as saying by the Russian Science Foundation.
As Sergey Alekseenko, laureate of the Global Energy Prize and member of the RAS, said in an interview with the Global Energy Association, moving away from using ozone-depleting freons and other industrial halogen-containing gases could solve the problem of ozone layer destruction. “As an alternative, manufacturers have started actively employing ozone-friendly freons, mainly hydrofluorocarbons of the Freon 134a type, which is now widely used in refrigerators. But both ozone-depleting and ozone-friendly freons are strong greenhouse gases. This is why they are also going to be banned from use in the near future,” he noted.
