This summer in Spain, there are moments when you look at the thermometer in disbelief. Temperatures reached 44ºC in some cities, and there is nothing better than air conditioning to combat constant suffocation. However, despite new models and continuous improvements, this technology still has its limitations in space cooling: it consumes a lot of energy, averaging around 1000 Wh, and in the vast majority of cases relies on hydrofluorocarbon refrigerants (HFCs), which emit powerful greenhouse gases. gases and make the main contribution to climate deterioration.
For years alternative cooling methods are being exploredusing methods ranging from magnetism to pressure, stretching or electric fields to Manipulating solid materials so that they absorb or release heat. Some have even combined three different methods to bring the temperature down by 9 degrees without the use of electricity. But few have come up with an entirely new way of cooling (and heating), as Drew Lilly and Ravi Prasher, scientists at the Lawrence Berkeley Lab in California, USA, can boast.
These two young engineers intend to take advantage of the potential offered by the ionocaloric cycle which, according to the results obtained, can compete with or even improve the efficiency of today’s refrigerants, without polluting the environment and with minimal energy consumption.
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“The refrigerant landscape is an unsolved problem,” says Lilly in a Berkeley Lab publication. “No one has developed a workaround which makes things cool, works efficiently, is safe and does not harm the environment. We believe that the caloric-calorie cycle can achieve all of these goals if done right.”
The key is in the salt
New methods and technologies for refrigeration are part of growing international restrictions on pollutant materials and gases. Signatories to the Kigali Amendment to the Montreal Protocol (which limits the use of substances that deplete the ozone layer), including Spain, have committed to reduce production and consumption of HFCs by at least 80% over the next 25 years. The researchers believe that ionocaloric cooling may play an important role in this change.
Lilly and Prasher’s initial findings were presented in December 2022 in the journal. The science. Its ion-based technique is based on the same physics as throwing salt on the pavement when a big storm rolls in in winter so that ice does not form on the road.
Salt involves applying a stream of ions (electrically charged atoms) in the soil to act on ionocaloric cycle occurs when a liquid freezes and vice versa. In this process, heat is stored or released so that the material can change from liquid to solid.
The researchers believe that by supplying a stream of ions to a medium passing through a cooled or heated system, it is possible to change its temperature. change in the melting point of a substance. “The first experiment showed a temperature change of 25 degrees Celsius using less than one volt (0.22 volts) – a higher temperature rise than other caloric technologies have demonstrated.” responsible persons assure, current researchers from the same Berkeley laboratory, from which 16 Nobel laureates came out.
To demonstrate theory in the lab, Drew Lilly used salt based on iodine and sodium, along with ethylene carbonate, a common organic solvent often used in lithium-ion batteries. This cheap and plentiful combination can solve many problems and also help cool our homes.
“There is potential to use refrigerants that not only have zero GWP (Global Warming Potential), but also have negative GWP,” Lilly said. “Use material such as ethylene carbonate can be carbon negativebecause it is produced using carbon dioxide as an input. So we could use CO2 from carbon capture.” In other words, the new ionocaloric refrigerant will not only not pollute the environment, but will also help to directly combat climate change.
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In addition to the GWP, there were two other fundamental elements that the researchers considered to be a priority: energy efficiency and cost of equipment, making it affordable and easy to manufacture. “On the first try, our data looks very promising in all three respects,” says Prasher.
Once its viability has been demonstrated in the laboratory, Researchers continue to work on various prototypes to determine how they can scale the technique to support large amounts of cooling. They are also looking to improve the amount of temperature change the system can handle and its efficiency so that it can compete in the market with existing solutions.
“We have a completely new thermodynamic cycle and structure that combines elements from different fields, and we have shown that they can work,” Prasher says. “Now, It’s time for experimentation to test different combinations of materials and techniques. that allow us to overcome engineering challenges,” he concludes.
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