Refrigeration is one of the most commercially used forms of thermodynamics. The second law of Thermodynamics allows us to extract heat from a cold body and expel it to the surroundings by doing some work.
Conventional refrigeration: The vapor compression cycle
The main principle of a refrigerant is that it gets heated on compression and gets cooled on expansion. This cooling effect on expansion allows the transfer of heat from the body to the refrigerant. Then it flows to the surroundings after compression. The whole cycle is known as vapor compression refrigeration.
Vapour Compression cycle
As a result, a low boiling highly stable vapor acts as a refrigerant. Common refrigerants chosen are ammonia, CO2, freon, and other fluorocarbons. A common problem these refrigerants possess is that if they leak, they are a huge threat to the environment. Most of the refrigerants come under greenhouse gases.
There are some alternative compounds proposed, but they are flammable at high temperatures. Hence, this poses severe safety hazards. In short, dealing with refrigerants presents severe environmental risks.
Either we have to find a non-toxic and non-inflammable material with desirable refrigeration properties or we must find a completely new way to cool and heat.
Refrigeration: Rubber bands to the rescue
“What we do with our device, instead of using a gas to provide entropy changes, we use a solid.”
– Dr.Ray Baughman
An elastic material heats on elongation and cools down when it regains its original structure. Similarly, if it twists, it gains heat and on untwisting, loses heat. These are special because both the phenomena look contradictory. The former property explains elastocaloric cooling, and the latter explains twistocaloric cooling.
“Invention is the natural outcome of creative thinking”
Dr.Ray combined both these principles on rubber fibers. Not only did he use rubber fibers, but also they tested using a wide variety of materials including non-elastic materials. A four-wire bundle of nickel-titanium was able to produce a temperature drop of 20.8°C.
Dr. Ray holds over 90 patents and is a recipient of numerous awards ranging from the Chemical Pioneer Award – American Institute of Chemists (1995) to the 2015 Inventor Award for Energy Harvesting Materials and Systems. He is in the top 1% Most Cited in Cross-Fields citations in 2018.
Refrigeration: A twist in the future
These researches establish a potential replacement of vapor compression cycles by twistocaloric cycles.
“If everyone has to think outside the box, maybe it is the box that needs fixing.”
Dr. Ray has laid a foundation upon which further researches to develop commercial refrigerators using twisted fibers and wires have spiced up. Subsequently, we can expect fridges made from elastic materials sooner than later.
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