Harnessing Energy from Transient Temperature Differences Using Phase Change Materials

This work explores the feasibility of powering IoT devices by harvesting energy from transient temperature differences, utilizing two distinct phase change materials in combination with a thermoelectric generator. The phase change materials store and release thermal energy during their respective phase transitions at different times, creating a sustained temperature gradient across the thermoelectric generator (TEG) over an extended period. We build upon an existing model to predict the thermal behaviour of the phase change materials under varying ambient conditions. Using the model and empirical evaluations, we demonstrate that a considerable spatial temperature gradient can be generated across the TEG from transient differences using PCMs with different thermal properties. For an experiment duration of 224 hours, a significant temperature difference exceeding 0.49°C was observed in more than 80% of the recorded measurements. We further provide insights into the amount of energy that can be harnessed using a prototype system that incorporates two PCMs and a TEG.