Engineers at the University of Texas at Dallas (UT Dallas) and Nankai University in Tianjin, China have developed a new refrigeration method that exploits the physical properties of twisted fibers.
In most modern refrigerators, items are kept cool through an energy expensive chemical process that uses an agent like freon. However, new research published in the journal Science has unraveled the mystery of a more energy efficient cooling method.
According Ray Baughman of UT Dallas and Zunfeng Liu, professor at Nankai University, their research has established that tightly twisting rubber or monofilament fibers until they are supercoiled (read: twisted at the molecular level) and then releasing them results in a dramatic cooling of the fibers.
The team calls this phenomenon twistocaloric cooling.
“This elastocaloric behavior of natural rubber has been known since the early 1800s. But to get high cooling from a rubber band, you have to release a very large stretch,” Baughman said. “With twistocaloric cooling, we found that all you have to do is release twist.”
Baughman added, “By employing opposite directions of twist and coiling, we engineered fibers that cool when stretched. This is quite unusual behavior since ordinary materials heat up when stretched.”
While Baughman and Zunfeng believe there are several opportunities to commercialize twistocaloric refrigeration, much more work is required before the technology will be consumer ready.
“Many challenges and opportunities exist on the path from these initial discoveries to the commercialization of twist fridges for diverse large- and small-scale applications,” said Baughman. “Among the challenges are the need to demonstrate refined devices and materials that provide application-targeted cycle lifetimes and efficiencies by recovering part of the inputted mechanical energy. The opportunities include using performance-optimized twistocaloric materials, rather than the few presently studied commercially available candidates.”
Still, more efficient modes of refrigeration would be a welcome addition to a warming world where any increases in energy efficiency can only help reduce humanity’s overall impact on the planet’s energy budget.