Elastocaloric cooling: From fundamental thermodynamics to solid state air conditioning

This article discusses fundamental thermodynamic concepts, as well as experimental investigations of elastocaloric cooling processes and presents a concept of a potential elastocaloric air conditioning device. Various cooling cycles suitable for elastocaloric cooling are introduced and the process efficiencies are determined based on a graphical approach. The graphical method is validated experimentally with a specially designed scientific test setup, which enables the measurement of mechanical and thermal process quantities. The material, a newly developed quaternary Ni-Ti-Cu-V alloy, is investigated in various thermodynamic cycles and an advanced cycle control is applied to increase the process efficiency. In addition, the influence of the thermal boundary conditions on the material and system efficiency is investigated. The results are compared with the values predicted by the graphical approach. Furthermore, a concept of a continuously operating elastocaloric air cooling device is introduced.