Researchers develop highly efficient heat-driven thermoacoustic refrigerator

https://techxplore.com/news/2024-02-highly-efficient-driven-thermoacoustic-refrigerator.html

"no moving parts, eco-friendly helium or nitrogen, reliable... what would be decreased COP with increased heat is now overcome by allowing part of acoustic power to be bypassedby with bypass eliminating temperature matching constraint, achieving energy flow field synergy... kW-scale prototype using helium (nitrogen almost as good) achieved 1.12 COP (2.7X higher), 2.53 kW cooling capacity at heating, ambient, and cooling temperatures of 450 ℃, 35 ℃, and 7 ℃... commercial air conditioning"

Related: In the elastocaloric cooling process, a refrigerator cools by flexing artificial muscles
https://techxplore.com/news/2024-04-elastocaloric-cooling-refrigerator-cools-flexing.html#google_vignette