Active operative heat storage application using thermoelastic martensitic transformation in TiNi-based alloy

We propose a new concept of heat-storage material that utilizes thermoelastic martensitic transformation in a TiNi-based alloy. In the material, the stored thermal energy is maintained over a wide temperature range between the thermal absorption and desorption temperatures, and the stored energy is released on demand by external stress on the ground of a latent heat of the stress-induced martensitic transformation. The heat-storage temperature range was effectively increased through a thermomechanical treatment without changing the amount of latent heat. The tensile force applied to the treated sample released to the environment more heat than the unbiased desorption temperature. The amount of heat released was in agreement with the values expected from the Clausius–Clapeyron equation and differential scanning calorimetry profiles. The amount of heat released was confirmed to remain unchanged up to the 9th cycle when the release process was repeated at 286 K by applying tension after heat absorption.