Continuous rotating bending NiTi sheets for elastocaloric cooling: Model and experiments

Abstract

Elastocaloric refrigeration using superelastic NiTi alloys has attracted much attention recently because it has a large energy saving potential, no environmental effects, and a low cost. Achieving the continuous operating of elastocaloric devices, i.e., separating the cold and hot areas on the NiTi alloys physically, benefits the efficient release and absorption of heat and avoids the reciprocal parts and intervals of outputs in the system. In this article, an analytical model including the temperature difference on the NiTi alloys and temperature span between the heat sink and heat source for continuous operating (elasto)caloric devices is presented. In order to validate the model, an experimental proof of concept was developed based on a set of rotating bending NiTi sheets with which the copper heat sink and heat source contact cyclically. Operations at different rotation speeds, applied strains, and heat transfer fluid velocities were performed to study the effects of operation variables on the cooling performance of the rotating bending NiTi sheets. The comparison between the model and experiments was given. The results in this article are significant for improving the cooling performance of continuous operating (elasto)caloric cooling and heat pumping devices.