Parametric analysis of a packed bed thermal storage device with phase change material capsules in a solar heating system application

The goal of this study is to investigate the effect of key design parameters on the thermal performance of the packed bed heat storage device by numerical calculation. A one-dimensional, non-equilibrium packed bed latent heat storage mathematical model was established and the applicability of the model was verified. The results demonstrate that the inlet temperature of the heat transfer fluid (HTF) had the greatest influence on each index. When the inlet temperature increased from 333 K to 363 K, exergy destruction increased threefold, effective heat storage time decreased by 67%, effective heat storage increased by 38%, and exergy efficiency decreased by 11%. The decrease of the capsule diameter had a positive effect on each evaluation index. According to the sensitivity analysis, the order of importance of each parameter within their variation range was HTF inlet temperature, HTF flow rate, PCM capsule size and PCM initial temperature.