Thermodynamic characterization shows multicaloric effects make for efficient refrigeration

The demand for artificial cold and refrigeration devices is high, and it only will continue to grow. Currently, many devices are not highly efficient and use climate-damaging refrigerants. One alternative is the use of devices based on multicaloric effects, which is more environmentally friendly. However, understanding of the thermal response of the materials, which can be used for multicaloric devices is still a challenge for scientists.

Gràcia-Condal et al designed a device to measure the thermal response of materials under the effect of a magnetic field and mechanical stress. Using their unique calorimeter, the team compared the multicaloric response of materials and showed it exceeds that of a single caloric effect.

“Modern society faces an important challenge in refrigeration,” said author Lluís Mañosa. “There is an increasing and huge demand of artificial cold, and the existing devices are not efficient enough and -- what is even worse -- they use climate-damaging refrigerants.”

Their findings revealed the combination of mechanical stress and magnetic field created a multicaloric effect, which outperforms the single caloric effect of a nickel-manganese-indium alloy.

“Both multicaloric entropy and temperature changes are significantly larger than their single caloric counterparts,” said Mañosa. “The reversibility of the caloric effect is also increased, and the operation temperature window is enlarged.”

The results mark the first characterization of all the thermodynamic quantities of multicaloric effects of a material through experimental determination.

“In the near future, new materials will be developed and thermodynamically characterized, which can ultimately be useful in designing efficient and environmentally friendly new refrigeration and energy-harvesting devices,” said Gutfleisch.

Source: “Multicaloric effects in metamagnetic Heusler Ni-Mn-In under uniaxial stress and magnetic field,” by Adrià Gràcia-Condal, Tino Gottschall, Lukas Pfeuffer, Oliver Gutfleisch, Antoni Planes, and Lluís Mañosa, Applied Physics Reviews (2020). The article can be accessed at https://doi.org/10.1063/5.0020755 .