Experimental investigation of high-temperature latent heat storage packed bed using alloy-based phase change materials

•High-efficiency latent heat storage at elevated temperatures utilizing Al-Si-based MEPCM in a packed bed system.•Enhanced heat exchange rates: 0.25–0.67 kW/L during charging and 0.13–0.535 kW/L during discharging.•Demonstrated considerable reduction in heat loss through the optimization of airflow rates and pellet sizes.•Achieved a peak round-trip efficiency of 0.93 under controlled temperature conditions.•Illustrated the impact of Reynolds numbers on heat exchange rates and overall system efficiency. This study explores the effectiveness of a high-temperature latent heat thermal energy storage (LTES) system incorporating Al-Si-based microencapsulated phase change material (MEPCM) composite pellets within a cylindrical packed bed. A parametric analysis was conducted to examine the impact of varying pellet sizes (1, 3, and 5 mm) and airflow rates (20–50 L min−1) on the efficiency of heat storage and discharge. The experimental approach included controlled charging and discharging cycles at temperatures ranging from 500 to 800 °C, with Reynolds numbers between 17.6 and 261. The findings indicate that the system achieved a maximum round-trip efficiency of 0.93, with no substantial gains observed beyond a Reynolds number of 150. Additionally, the results reveal the importance of minimizing heat loss to improve system efficiency, particularly during the discharge phase. These insights are crucial for optimizing the design and operational parameters of high-temperature LTES systems to enhance energy storage efficiency.