A new type of crystal that absorbs heat at sufficiently high pressure may lead to the creation of climate-friendly refrigerators and air conditioners, says the scientific journal “Science”. It is intended to be an alternative to currently used liquid coolers.
Refrigerators and air conditioners are able to cool by circulating liquid, which absorbs heat through the evaporation and condensation cycle. However, refrigeration installations often leak, and many such liquids evaporate and leak into the atmosphere, contributing to the greenhouse effect.
An alternative to current refrigerators
Now in the scientific journal “Science”, scientists from Deakin University in… Australia (including Samantha L. Piper, Douglas R. MacFarlane and Jenny Pringle) claim to have created an alternative to liquid coolers using “plastic crystals” (organic, ionic, plastic crystals – OIPC).
As the researchers point out in their article, under sufficient pressure, the molecules of these OIPC crystals change from random orientation to aligning into an ordered lattice. Then, when the pressure returns to lower values, they become disordered again. When they enter a disordered state, crystals absorb heat, effectively cooling their surroundings.
“Pressure” cooling has been studied before, but most materials underwent this type of transformation at temperatures unsuitable for refrigeration purposes. However, the heat absorption capacity of the crystals tested in Australia starts at temperatures from -37 degrees C to 10 degrees C, which is an appropriate range for home refrigerators and freezers.
Laboratory testing stage
For now, the technology is at the laboratory testing stage. The pressures needed are very high – hundreds of times greater than atmospheric pressure and equivalent to being thousands of meters underwater. In addition, with repeated use, the crystal can absorb less heat as the lattice that the molecules create becomes increasingly taut.
Still, in the paper's abstract, the researchers argue that “the barocaloric reactions achieved with these prototype OIPC-BCs can be tuned through structural modification of ions” and “this broad matrix of possible structure-function combinations indicates the scope of OIPCs as a new class of materials for efficient and sustainable cooling technologies.
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