FROSTBIT · First Regenerative sOlid-STate Barocaloric refrIgeraTor

Greenhouse gas emissions for refrigeration systems worldwide were in 2019 equivalent to the whole EU emissions. Long-term sustainability requires improvements in energy efficiency, with a huge return on investment obtained from even slight improvements. The mechanocaloric effect, which refers to adiabatic temperature changes induced by stress or pressure, is one of the most promising energy-saving new technology for cooling systems. Mechanocaloric research produced in only 14 years highly performing materials, overcoming electrocaloric and magnetocaloric materials. Furthermore, mechanocaloric materials use non-critical, cheap, abundant and non-toxic elements. Recent papers evidenced colossal barocaloric effects around the Spin CrossOver (SCO) temperatures for some molecular complexes. The FROSTBIT project overall objective is to develop the first operative refrigerator based on a radically new solid-state technology by using barocaloric materials in a regenerative cooling device. In more specific objectives, the project aims to 1) Design sustainable syntheses of compounds for barocaloric applications, exploring synthetic pathways to optimize costs and low environmental impact/low carbon footprint vs. barocaloric performances; 2); Shape SCO materials in order to obtain densified objects with centimetric sizes, study extensively their thermal, mechanical and barocaloric behaviour and explore the optimization of those properties through the preparation of composites ceramics 3) Model, design and build the constituting elements of a barocaloric refrigerator: barocaloric regenerator, thermal and pressure fluid circuits. While the technology could potentially address a wide range of temperature, as an initial step we propose to specifically design and build a refrigerator yielding 100 W of cooling power at room temperatures and providing a temperature span of at least 20 K with a target COP between 4 and 6 (corresponding to 30% of Carnot efficiency).