Compression Behaviors of Different Geometry-Designed NiTi Refrigerants

A promising elastocaloric cooling technology (one of the solid-state cooling technologies) does not require any potentially harmful vaporous refrigerants. Its basic working principle, the martensitic transformation and its reverse transformation of shape memory alloys (SMAs) such as NiTi, NiTiCu, and NiFeGaC is one of the first-order non-diffusible phase transitions between a high-temperature phase (the austenite phase) of a B2 cubic structure and a low-temperature phase (the martensite phase) of a B19' monoclinic structure. This paper investigates the compression behaviors of different NiTi regenerator structures through fatigue tests. An optimized 3-layer sample shows promise to be used in elastocaloric cooling prototypes and gives insight into the structural optimization of regenerators.