Thermal energy storage enhancement using a Bio-Inspired cylindrical structure with hybrid phase change materials

Schematic of the experimental TES setup. • Bio-inspired cylindrical PCM structure improves thermal performance. • Hybrid PCM (SAT + Al chips) achieves 1.865 kJ/min charging rate. • Highest PCM peak temperature reached: 92.5 °C. • Superior post-sunset thermal retention with SAT-based design. • Low-cost, scalable TES setup tested under real solar conditions. This study investigates a solar-powered latent heat thermal energy storage (LHTES) device. The design features a bio-inspired cylindrical chain-mill structure integrated with hybrid phase change materials (PCMs). The proposed design optimizes geometry and metallic thermal bridging to enhance heat transfer and retention, eliminating the need for costly nanomaterials. A solar tower configuration featuring eight reflectors was employed to evaluate six phase change material (PCM) designs utilizing paraffin wax and sodium acetate trihydrate (SAT), both with and without the inclusion of aluminum. The tests were conducted under actual sunlight conditions. Temperature fluctuations were measured using K-type thermocouples to evaluate charging, discharging, thermal retention, and reliability. The optimal configuration employed SAT, 5 vol% Al chips, and a bio-inspired structure. The system is capable of achieving maximum temperatures of 92.5 °C for phase change material (PCM) and 124 °C for water. The configuration achieves a charging rate of 1.865 kJ/min and a discharging rate of 0.825 kJ/min, respectively. A 125 % increase in thermal reaction compared to pure paraffin is demonstrated. SAT-based systems had a water-cooling rate of 0.200 °C/hr during discharging, compared to 0.330 for paraffin, confirming their improved thermal retention. The results show that bio-inspired geometry and low-cost metallic inclusions can outperform nanomaterial-enhanced systems while maintaining recyclability, scalability, and economic feasibility. This practical, sustainable solution offers strong potential for solar-integrated thermal storage in residential and small-scale industrial heating applications.