Thin-walled Ni-Ti tubes under compression: ideal candidates for efficient and fatigue-resistant elastocaloric cooling

• DOI: 10.1016/j.apmt.2020.100712
• Publication Date: 2020-06-06T03:46:56Z
• Authors: Luka Porenta; Parham Kabirifar; Andrej Žerovnik; Matjaž Čebron; Borut Žužek; Matej Dolenec; Miha Brojan; Jaka Tušek
• Keywords: Pseudoelasticity; Vapor-compression refrigeration

Elastocaloric cooling is emerging as one of the most promising alternatives to vapor-compression technology. It based on elastocaloric effect (eCE) shape memory alloys (SMAs), which occurs due a stress-induced martensitic transformation (superelasticity). In recent years, several proof-of-concept devices have been developed and best them already achieved commercially relevant characteristics. However, proposed are not yet ready for commercialization, mostly their short fatigue life, consequence tensile loading. The life can be significantly improved if material instead subjected compressive loading, but mechanical instabilities (buckling) poor heat transfer bulky geometries (favorable compression) major challenges overcome when designing compressed elements. Here, we show first time that thin-walled Ni-Ti tubes, allow rapid transfer, withstand more than 106 loading cycles without any degradation eCE while maintaining high efficiency (coefficient performance) adiabatic temperature changes 27 K. This largest, directly measured, durable in high-cycle regime date, so opens up new avenues development efficient devices.