DAVID NIELD FROM SCIENCE ALERT
Say hello to ionocaloric cooling: a new way to lower the mercury that has the potential to replace existing methods with something that is safer and friendlier to the planet.
Typical refrigeration systems transport heat away from a space via a gas that cools as it expands some distance away. As effective as this process is, some of the choice gases we use are also particularly unfriendly to the environment.
There is, however, more than one way a substance can be forced to absorb and shed heat energy.
A new method developed by researchers from the Lawrence Berkeley National Laboratory and the University of California, Berkeley, in the US takes advantage of the way that energy is stored or released when a material changes phase, as when solid ice turns to liquid water, for example.
Raise the temperature on a block of ice, it’ll melt. What we might not see so easily is that melting absorbs heat from its surroundings, effectively cooling it.
One way to force ice to melt without needing to turn up the heat is to add a few charged particles, or ions. Putting salt on roads to prevent ice forming is a common example of this in action. The ionocaloric cycle also uses salt to change a fluid’s phase and cool its surroundings.
“The landscape of refrigerants is an unsolved problem,” says mechanical engineer Drew Lilley, from the Lawrence Berkeley National Laboratory in California. “No one has successfully developed an alternative solution that makes stuff cold, works efficiently, is safe, and doesn’t hurt the environment.”
“We think the ionocaloric cycle has the potential to meet all those goals if realized appropriately.”
The researchers modeled the theory of the ionocaloric cycle to show how it could potentially compete with, or even improve upon, the efficiency of refrigerants in use today. A current running through the system would move the ions in it, shifting the material’s melting point to change temperature.
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The team also ran experiments using a salt made with iodine and sodium, to melt ethylene carbonate. This common organic solvent is also used in lithium-ion batteries, and is produced using carbon dioxide as an input. That could make the system not just GWP [global warming potential] zero, but GWP negative.
