May 31, 2023 03:59 PM
https://physics.aps.org/articles/v16/91#c2
INTRO: Refrigeration systems that use materials that cool in response to an applied electric, magnetic, or mechanical force offer environmentally friendly alternatives to the greenhouse-gas-leaking ones found in most homes and factories (see Feature: In Hot Pursuit of 21st Century Cooling). Now researchers have demonstrated a cost-effective, scalable version of one of these so-called “caloric cooling” systems. Their approach, which uses a material that responds to a mechanical force, exceeds performance records set by methods that rely on magnetic fields. The researchers say their technology is also much less expensive to make and to operate and could be ready for commercial use within a year.
Magnetic-based cooling systems had an early brush with fame in 1998 with the demonstration of a near-room-temperature system that kept its contents cold for 1500 hours. In that system, a magnetic field was applied to a magnetocaloric material, resulting in a temperature increase, as atomic vibrations compensated for the entropy lost as unpaired spins in the material aligned. Turning the field off reversed that increase, allowing the material to act as refrigerant that could be used in the cooling coils of a household fridge. But inducing the magnetocaloric effect requires strong (> 1 tesla) magnetic fields, which can only be provided by expensive permanent magnets that contain rare-earth alloys.
An alternative approach is to use an elastocaloric material... (MORE - details)
INTRO: Refrigeration systems that use materials that cool in response to an applied electric, magnetic, or mechanical force offer environmentally friendly alternatives to the greenhouse-gas-leaking ones found in most homes and factories (see Feature: In Hot Pursuit of 21st Century Cooling). Now researchers have demonstrated a cost-effective, scalable version of one of these so-called “caloric cooling” systems. Their approach, which uses a material that responds to a mechanical force, exceeds performance records set by methods that rely on magnetic fields. The researchers say their technology is also much less expensive to make and to operate and could be ready for commercial use within a year.
Magnetic-based cooling systems had an early brush with fame in 1998 with the demonstration of a near-room-temperature system that kept its contents cold for 1500 hours. In that system, a magnetic field was applied to a magnetocaloric material, resulting in a temperature increase, as atomic vibrations compensated for the entropy lost as unpaired spins in the material aligned. Turning the field off reversed that increase, allowing the material to act as refrigerant that could be used in the cooling coils of a household fridge. But inducing the magnetocaloric effect requires strong (> 1 tesla) magnetic fields, which can only be provided by expensive permanent magnets that contain rare-earth alloys.
An alternative approach is to use an elastocaloric material... (MORE - details)