Golf-ball-inspired phase change material capsule: Experimental and numerical simulation analysis of flow characteristics and thermal performance

Latent heat thermal energy storage (TES) has garnered considerable attention in solar energy storage. However, its development remains limited due to the poor flow characteristics and thermal performance of the phase change material (PCM) capsule. The dimples of the golf ball can disturb the fluid, reduce external differential pressure resistance, and enhance internal natural convection intensity, the idea of a novel PCM capsule was proposed. Both experimental and numerical analyses revealed improvements achieved by the novel capsule design. The constrained and unconstrained melting time was reduced by 8.60% and 9.10%, respectively, compared to conventional spherical capsules. Additionally, we proposed a dimensionless comprehensive evaluation method (DCEM) to assess the performance of capsules with different structures in terms of flowability, melting ability, and economic viability. It was observed that targeted enlargement and deepening of the dimples substantially improved the holistic performance of the capsule. The optimized individual capsule showcased a remarkable 38.99% improvement in holistic performance, the TES system filled with the capsules demonstrated a reduction in full charging time by 9.18% and an increase in average temperature by 9.06%.