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OK! Metallic solid-state refrigerant tubes for elastocaloric cooling, an environmentally friendly cooling technology. Credit: Jiaqi Dai/Maryland Engineering
Air conditioning, refrigeration and other cooling technologies now account for more than 20 percent of global energy consumption, while the refrigerants they use have a global warming potential thousands of times higher than carbon dioxide. In a recent study in the journal Science, a team led by Maryland engineering professors Ichiro Takeuchi, Reinhard Radermacher, and Yunho Hwang presented a powerful elastocaloric cooling system that could represent the next generation of cooling devices.
Takeuchi calls it “an entirely different, entirely green, eco-friendly refrigeration technology that bypasses chemical refrigerants and essentially relies on pushing and pulling pieces of metal to create cooling.”
Caloric materials—including magnetocaloric, electrocaloric, and elastocaloric materials—can undergo phase transitions and releases, and absorb heat upon the application of different fields and mechanical forces. The key feature is the compression and relaxation of fatigue-resistant nickel-titanium (NiTi) tubes configured in a versatile multimode heat exchange architecture.
“More than a decade ago we were just playing with a NiTi wire,” Takeuchi said. “By stretching you could achieve a significant cooling effect that you could feel with your hand. That’s when we started thinking about applying the concept to a cooling device.” Video showing live operation of a multimode elastocaloric cooler (at 10x speed). Superelastic NiTi tube bundles are compressed using hydraulic actuators. In this configuration, two upper bundles and two lower bundles operate together in direct work recovery mode to deliver 150W of cooling capacity. The left diagram monitors the temperature of the cooling medium (water) at the outlet points of the bundles (blue: top; red: bottom). The right diagram shows the temperatures of the heat source (blue) and the heat sink (red) as a function of time. Photo credit: Maryland Engineering
The team says it’s possible to improve the performance of their system enough for the technology to become commercially viable within a few years. A current prototype can generate 200 watts of cooling power, enough to power a compact wine cooler. It is planned to later expand to window units, whole-home cooling systems, and commercial HVAC systems.
For more information: Suxin Qian et al., High Performance Multimode Elastocaloric Cooling System, Science (2023). DOI: 10.1126/science.adg7043
Journal Information: Science