Effect of recycled ceramic particle size on heat transfer and charging dynamics in PCM-based thermal storage systems

Heating and cooling account for half of global energy demand, making efficient thermal energy storage (TES) central to decarbonization. Phase change materials (PCMs) can store large amounts of heat, but their low thermal conductivity slows charging and discharging, limiting system performance. To overcome this, metallic fins and foams have been traditionally used to accelerate heat transfer, yet these add complexity, cost, and durability challenges. Here, we explore an alternative pathway: embedding recycled ceramic particles into PCMs to enhance heat transfer while avoiding corrosion and stability issues. Using a lab-scale TES unit, we test composites with different ceramic particle sizes and show that finer particles accelerate charging, enable faster discharge, and suppress overheating compared with coarser particles. This simple modification improves PCM cycling efficiency and reliability. • Utilizing recycled ceramic and PCM compound as a latent heat storage medium. • Small particles enable a faster charging process. • Temperature gradient and overheating rise with larger particles. • Finer aggregates reduce specific heat input per mass of PCM by 10%.