Introducing ionocaloric cooling. This is a new way to lower temperatures and has the potential to replace existing cooling methods with safer and more earth-friendly processes.
A typical refrigeration system transports heat from space through a fluid that absorbs heat as the liquid evaporates into a gas, which is then transported through sealed tubes and condensed back into the liquid. Although this process is effective, some of the carefully selected materials used as refrigerants are not particularly environmentally friendly.
However, there are multiple ways to force materials to absorb and release thermal energy.
Developed by researchers at Lawrence Berkeley National Laboratory and the University of California, Berkeley, and published last year, the method relies on energy being released when a substance changes phase, such as when solid ice turns into liquid water. It uses a storage or release mechanism. example.
If you raise the temperature of a block of ice, it will melt. What may not be so readily apparent to us is that melts absorb heat from their surroundings and cool themselves effectively.
One way to force ice to melt without increasing heat is to add some charged particles or ions. Spreading salt on roads to prevent ice formation is a common example of this in practice. Ionocaloric cycles use salt to change the phase of a fluid and cool its surroundings.
“The situation around refrigerants is an open question.” Mechanical engineer Drew Lilly said: From Lawrence Berkeley National Laboratory in California in January 2023.
“No one has succeeded in developing an alternative solution that cools things, works efficiently, is safe, and has no negative impact on the environment. If properly realized, the ionocaloric cycle achieves all of these goals. We think it can be done.”
The researchers modeled the theory of the ionocaloric cycle and showed how it competes with, and has the potential to even improve, the efficiency of currently used refrigerants. When electrical current is passed through the system, ions within the system move, changing the melting point of the material and changing its temperature.
The researchers also conducted experiments using a salt made from iodine and sodium to dissolve ethylene carbonate. This common organic solvent is also used in lithium-ion batteries and is produced from carbon dioxide. Then your system may become more than just GWP [global warming potential] Although it is zero, GWP is negative.
In this experiment, a temperature change of 25 degrees Celsius (45 degrees Fahrenheit) was measured by applying a charge of less than 1 volt. This result exceeds what other caloric technologies have been able to achieve to date.
“There are three things we are trying to balance: GWP of the refrigerant, energy efficiency, and the cost of the equipment itself.” Mechanical engineer Ravi Prasher said: from Lawrence Berkeley National Laboratory.
“From the first trial, our data looks very promising on all three aspects.”
Vapor compression systems currently used in refrigeration processes rely on gases with high GWP, such as various hydrofluorocarbons (HFCs).
Countries that signed the Kigali Amendment have committed to reducing HFC production and consumption by at least 80% over the next 25 years, and ionocaloric cooling could play a major role in this.
Now, researchers need to take this technology out of the lab and into a practical system that can be used commercially and scaled up without problems. Eventually, these systems could be used for heating as well as cooling.
“We have a completely new thermodynamic cycle and framework that integrates elements from different disciplines, and we have shown that it works.” Prasher said..
“Now is the time for experimentation, testing different combinations of materials and technologies to address engineering challenges.”
This research science.
A previous version of this article was published in January 2023.
