Key Parameters for Barocaloric Cooling and Heating

Heating and cooling markets sum up a 70% share of energy consumption worldwide and urge the shift towards more efficient and low-carbon solutions [1, 2]. Heating market heavily relies on fossil fuel-dominated technologies. Cooling market relies on the use of refrigerant gases that have been severely in the spotlight of environmental protocols and EU regulations in view of their high Global Warming Potential and ozone-depletion properties.<br/><br/>In the last decades, substantial research effort has been concentrated on the development of alternative, more sustainable technologies based on caloric materials [3], which can exhibit a giant thermal response in the vicinity of a phase transition under the influence of a magnetic field, an electric field, or mechanical stress. Particularly, barocaloric materials are blossoming into calorics with the outbreak of new classes of materials displaying colossal thermal effects that compare to those of refrigerant gases [4, 5].<br/><br/>However, implementing these promising materials still remains preliminary, which poses a challenge from both the materials science and engineering viewpoints. In this regard, I will review the state-of-the-art caloric materials and the conditions yielding enhanced thermal responses. I will discuss the key parameters related to materials cyclability and heat transfer phenomena to be addressed to match applications’ demands and design constraints.<br/><br/>[1] IEA, ‘Heating’ (2021). Available at: https://www.iea.org/reports/heating<br/>[2] IEA, ‘The Future of Cooling: Opportunities for energy-efficient air conditioning’ (2018). Available at: https://www.iea.org/reports/the-future-of-cooling<br/>[3] Moya, Xavier, and N. D. Mathur. "Caloric materials for cooling and heating." <i>Science</i> 370.6518 (2020): 797-803.<br/>[4] Li, Bing, et al. "Colossal barocaloric effects in plastic crystals." <i>Nature</i> 567.7749 (2019): 506.<br/>[5] Lloveras, Pol, et al. "Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol." <i>Nature communications</i> 10.1 (2019): 1803.