Say hello to ionocaloric cooling: a new method of reducing mercury that has the potential to replace existing methods with something that is safer and kinder to the planet.
Typical refrigeration systems transport heat away from a space via a gas, which cools as it expands some distance. As effective as this process is, some of the selected gases we use are also particularly harmful to the environment.
However, there is more than one way a substance can be forced to absorb and release thermal energy.
A new method, developed by researchers at Lawrence Berkeley National Laboratory and the University of California, Berkeley, in the US, takes advantage of the way energy is stored or released when a material changes phase, such as . B. when solid ice turns into liquid water example.
Raise the temperature on a block of ice, it will melt. What we may not see easily is that melting absorbs heat from its surroundings and effectively cools it.
One way to melt ice without having to turn up the heat is to add a few charged particles or ions. Spreading salt on roads to prevent ice formation is a common example of this. The ionocaloric cycle also uses salt to change the phase of a liquid and cool its surroundings.
“The refrigerant landscape is an unsolved problem,” says mechanical engineer Drew Lilley of Lawrence Berkeley National Laboratory in California. “No one has successfully developed an alternative solution that cools stuff, works efficiently, is safe and doesn’t pollute the environment.”
“We believe the ionocaloric cycle has the potential to achieve all of these goals if implemented appropriately.”
The researchers modeled the theory of the ionocaloric cycle to show how it could potentially rival or even improve the efficiency of refrigerants used today. A current flowing through the system would move the ions within it and shift the melting point of the material to change the temperature.
The team also conducted experiments using a salt of iodine and sodium to melt ethylene carbonate. This common organic solvent is also used in lithium-ion batteries and is manufactured using carbon dioxide as an input. That could make the system not only GWP [global warming potential] Zero but negative GWP.
A temperature shift of 25 degrees Celsius (45 degrees Fahrenheit) was measured through the application of less than a single volt charge in the experiment, a result that surpasses what other caloric technologies have previously achieved.
“There are three things we’re trying to balance: the GWP of the refrigerant, energy efficiency, and the cost of the equipment itself,” says mechanical engineer Ravi Prasher of Lawrence Berkeley National Laboratory.
“From the first attempt, our data looks very promising in relation to all three aspects.”
The vapor compression systems currently used in refrigeration processes are based on gases with high GWP, such as e.g. B. various hydrofluorocarbons (HFCs). Countries that have signed the Kigali Amendment have committed to reducing HFC production and consumption by at least 80 percent over the next 25 years — and ionocaloric cooling could play a major role in that.
Now researchers need to take the technology out of the lab and into practical systems that can be used commercially and scale up easily. Finally, these systems could be used for both heating and cooling.
“We have this brand new thermodynamic cycle and framework that brings together elements from different fields, and we’ve shown it can work,” says Prasher.
“Now is the time to experiment, to test different combinations of materials and techniques to overcome the technical challenges.”
The research was published in Science.