Modeling and Characterization of PCM-Based Thermal Energy Harvesting

This paper investigates the feasibility of using phase change materials (PCMs) to harvest the environmental thermal energy, which is often associated with a relatively low temperature differential, less than 100°C. First, we develop a thermodynamic model for an idealized setting based on Tait equation of state, thereby deriving a theoretical upper limit of the thermal efficiency that can be achieved using PCMs. Next, we couple the thermodynamic model with a structural mechanics model based on Kirchhoff-Love plate theory, and predict the performance of specific PCM-based energy harvesters that convert the harvested energy into mechanical energy. To validate the thermomechanical model and demonstrate the feasibility of the underlying approach, we present the development and characterization of a prototype device. The measured specific energy and the prediction of the thermomechanical model are in close agreement.