Analysis of Melting Dynamics and Parametric Optimization in Encapsulated Phase Change Materials for Thermal Energy Storage

Phase change materials (PCMs) effectively store thermal energy via latent heat absorption/release during solid-liquid phase transitions. Salt hydrates and paraffin waxes melting within 30 degrees C-75 degrees C are suited for low-temperature applications. However, inherent challenges include poor thermal conductivity and material leakage needing encapsulation. Here, we employ computational fluid dynamics (CFD) simulations to systematically elucidate design parameters optimizing the performance of encapsulated PCM thermal energy storage (TES) systems. Spherical capsules containing paraffin wax or salt hydrate PCMs were modeled under varied encapsulation radii (16-58 mm) and shell thicknesses (18-72 mm) using stainless steel. Increasing radius exponentially extended melting times due to declining surface area-to-volume ratios, indicating smaller subdivided capsules accelerate heat transfer. An optimum 54-55 mm thickness maximized efficiency before reductions from lessened surface effects. Salt hydrate doubled the volumetric storage density to 9.032 $/kWh versus paraffin, highlighting the importance of suitable PCM selection. Through elucidating size, containment and material impacts, these CFD analyses provide valuable insights guiding encapsulated TES system optimization for sustainable thermal management applications.