Peridynamic analysis of thermal behaviour of PCM composites for heat storage

One possibility to utilise excess energy from electricity generation or other industrial processes is to use thermal energy storage systems based on phase change materials (PCM). These systems can accumulate and release significant amounts of heat energy during the phase transitions. The volume and properties of PCM undergo rapid changes during the transitions, creating strong physical non-linearities and geometric discontinuities. Describing this complexity with local formulations of the physical processes, i.e., formulations with differential equations, makes the numerical solutions of the correspond- ing problems challenging. This paper presents a numerical approach for the analysis of such physically complicated systems based on Peridynamics. The approach is illustrated by modelling and analysing the thermal behaviour of a PCM. The computational challenges associated with simulating composite structures with large differences in the heat conductivity of their components are addressed by investigating the influence of different types of peridynamic kernels and their numerical implementation. The results demonstrate that the solution is significantly influenced by the definition of the average thermal conductivity of the peridynamic bonds. The proposed modelling frame- work provides the base for developing a precise thermo-hydro-mechanical description of PCM composites that can fully represent the complex physical behaviour of thermal energy storage systems.