Elastocaloric cooling of shape memory alloys: A review

Abstract Elastocaloric cooling technology based on shape memory alloys (SMAs) exploits the caloric effect generated by stress-induced phase transformation of elastocaloric materials to realize refrigeration. It is characterized by eco-friendliness, high efficiency and energy saving and thus has been considered as one of the most promising candidates to replace the conventional vapor-compression cooling technology. Compared with magnetocaloric, electrocaloric and barocaloric refrigeration technologies, elastocaloric cooling balances cost, refrigeration capacity and efficiency, and feasibility. The review presents an overview of elastocaloric cooling from the fundamentals to the device design. We firstly describe the thermodynamic fundamentals and the characterization methods of the elastocaloric effect. Secondly, the research progress and the challenges in NiTi-based, Cu-based, Fe-based, and ferromagnetic SMAs as elastocaloric refrigerants are summarized. Furthermore, the development and the application prospects of high-performance elastocaloric materials are proposed. Finally, the advance of elastocaloric cooling prototypes is also analyzed and discussed. This review tries to outline the open crucial questions and to provide an insight to the community for further investigations of clean elastocaloric cooling.