Say hello to ionocaloric refrigeration: a new way to lower mercury levels that could replace existing methods with something safer and more planet-friendly. Typical refrigeration systems remove heat from the room using a gas that expands a certain distance. Despite the efficiency of this process, some of the gases we use are also particularly harmful to the environment. However, there is more than one way for a substance to absorb and release heat energy.

The new method, developed by researchers at Lawrence Berkeley National Laboratory and the University of California, Berkeley in the US, takes advantage of how energy is stored or released when a material changes phase, such as when solid ice turns into liquid water. . Raise the temperature of a piece of ice and it will melt. What we may not realize so easily is that melting absorbs heat from the environment, effectively cooling it.

One way to melt ice without having to raise the temperature is to add some charged particles or ions. Sprinkling salt on roads to prevent ice buildup is a typical example of this. The ionocaloric cycle also uses salt to change the liquid phase and cool its environment.

“Refrigerants are an open issue,” says mechanical engineer Drew Lilley of the Lawrence Berkeley National Laboratory in California. “No one has come up with an alternative solution that cools things down, works efficiently, is safe, and does not harm the environment.”

“We believe the ionocaloric cycle has the potential to achieve all of these goals if implemented properly.”

The researchers modeled the ionocaloric cycle theory to show how it could potentially compete with and even improve the refrigerants used today. A current through the system will move the ions in it, shifting the melting point of the material and changing the temperature.

The team also conducted experiments using a salt made of iodine and sodium to dissolve ethylene carbonate. This common organic solvent is also used in lithium-ion batteries and is produced using carbon dioxide as a raw material. This can make the system more than GWP [потенціал глобального потепління] zero, but the GWP is negative.

The experiment measured a temperature shift of 25 degrees Celsius (45 degrees Fahrenheit) by applying less than one volt of charge, a result that exceeds those achieved by other caloric technologies.

“There are three things we’re trying to balance: the GWP of the refrigerant, the energy efficiency, and the cost of the equipment,” says mechanical engineer Ravi Prasher of Lawrence Berkeley National Laboratory. “On the first try, our data looks very promising in all three of these aspects.”

Vapor compression systems currently used in refrigeration processes are based on gases with high GWP, such as various hydrofluorocarbons (HFCs). Countries that signed the Kigali Amendment have committed to reducing the production and consumption of HFCs by at least 80 percent over the next 25 years, and ionocaloric refrigeration can play an important role in this.

Researchers now need to move the technology from the lab to practical systems that are commercially available and easily scalable. Eventually, these systems can be used for both heating and cooling.

“We have an entirely new thermodynamic cycle and framework that brings together elements from different fields, and we’ve shown that it can work,” Prascher says. “Now it’s time for experiments to test different combinations of materials and techniques to meet engineering challenges.”