Experimental validation of thermo-mechanical properties for novel elastocaloric material.

Elastocaloric effect utilizes the latent heat associated with a stress-induced martensitic phase transformation in shape memory alloys to generate heating and cooling. In recent prototypes, the elastocaloric material acts as regenerative heat exchanger creating some unique challenges in heat pump applications, especially the strain non-uniformity across the regenerator. This study employs a simulation-based approach to optimize the transformation temperature gradient profile in NiTi tubes, demonstrating a reduction in strain maldistribution by 73% and 36% for linear and sigmoid profile, respectively. Experimental validation of in-situ prepared gradient NiTi tubes revealed a strong agreement between simulated and measured local strain distributions, along with a reasonable correlation in local temperature change. The implementation of graded transformation profiles was further found to enhance the operational temperature range of elastocaloric systems, presenting a promising pathway for improving the practical viability of elastocaloric cooling technologies.