Experimental and numerical investigation of a eutectic salt hydrate phase change material thermal storage unit for building heating application

Salt hydrate phase change materials (SHPCMs) stand out as exceptionally promising media for compact thermal energy storage, combining high latent-heat capacity with low material cost. This study investigates a compact heat energy storage unit filled with a eutectic SHPCM, tailored for building heating applications. A purpose-built test rig was commissioned to quantify the charging and discharging performance of the thermal-energy storage unit under controlled variations in heat-source temperature, flow rate and inlet orientation. The eutectic SHPCM71 exhibited a phase-change temperature of 71.06 °C and a latent heat of 160.54 kJ·kg −1 , respectively. The heat energy storage unit demonstrated a high thermal efficiency of approximately 90.84% and excellent thermal insulation properties. Numerical simulations validated the experimental findings, indicating that under the heat source condition of 2 L/min and 85 °C, the eutectic SHPCM71 was entirely melted within 100 min. These findings underscore the promise of salt-hydrate thermal energy storage systems for efficient, scalable building heating applications, particularly in scenarios requiring integration with valley electricity or solar thermal energy.