Performance analysis of packed bed latent heat storage system for high-temperature thermal energy storage using pellets composed of micro-encapsulated phase change material

High temperature latent heat storage has gained increasing attention owing to its potential in the integration of renewable energy sources. This study is a novel experimental investigation on the heat storage performance of a horizontal packed bed containing composites comprising Al-Si-based microencapsulated phase change material in a high-temperature air heating system. The pellet type composites with 3 mm is tested here in a 1L scale packed bed heat exchanger at airflow rates between 75 and 150 L min−1. The composite exhibited a narrow phase change temperature range and high heat storage/release characteristics. As the airflow increased, the phase change time of the composite decreased, and the heat exchanging rate increased. The heat exchange efficiency during charging and discharging ranged from 71.0 % to 98.3 % and 69.0 %–90.2 %, respectively. In the discharging mode, although supercooling which comes from the microencapsulated phase change material, was observed, this did not noticeable effect on the heat transfer.