Investigation of the Heat Storage Capacity and Storage Dynamics of a Novel Polymeric Macro-Encapsulated Core-Shell Particle Using a Paraffinic Core

Abstract

Thermal energy storages represent important devices for the decarbonisation of heat; hence, enabling a circular economy. Hereby, important tasks are the optimisation of thermal losses and providing a tuneable storage capacity, as well as tuneable storage dynamics for thermal energy storage modules which are composed of either sensible or phase change-based heat storage materials. The thermal storage capacity and the storage dynamics behaviour are crucial for fulfilling certain application requirements. In this work, a novel macro-encapsulated and spherical heat storage core-shell structure is presented and embedded in a supercritical ammonia working fluid flow field. The core of the macro-capsule is built by an organic low molecular weight substance showing a solid–liquid phase transition in a respective temperature zone, where the shell structure is made of polyvinylidene fluoride. Due to the direct coupling of computational fluid dynamics and the simulation of the phase transition of the core material, the influence of the working fluid flow field and shell thickness on the time evolution of temperature, heat transfer coefficients, and accumulated heat storage is investigated for this newly designed material system. It is shown that due to the mixed sensible and phase change storage character, the shell architecture and the working fluid flow field, the heat storage capacity and the storage dynamics can be systematically tuned.