Impact of Varying the Number of Heat Exchangers Used in the Latent Heat Thermal Energy Storage Unit on the Thermal Performance

Abstract

Latent heat thermal energy storage is one of the most relevant methods allowing to provide a solution of the energy supply–demand dilemma. A novel structure of latent heat thermal energy storage (LHTES) unit is designed and manufactured, with multireduced finned U-tubes heat exchangers, while the phase change material is filled in the tube and air flows through the finned surfaces. To increase the stored thermal energy and improve the thermal performance of the latent heat thermal energy storage unit, this experimental study suggests varying the number of reduced heat exchangers used instead increasing the size of a heat exchanger. By using paraffin as phase change material and air as a heat transfer fluid, the thermal charging and discharging characteristics of the storage unit were analyzed. Parameters of thermal performances including temperature distribution of phase change material, heat stored/released, thermal storage efficiency, effectiveness evolution, and total charging/discharging time were analyzed. The experimental results show that using two and three heat exchangers can increase the stored energy by 207% and 298% compared to that using one heat exchanger, respectively. The average effectiveness is increased by 125% and 199%. The designed LHTES unit provides more flexibility and adaptability for real application, and it has a wide application prospect in the fields of air conditioning and solar energy storage.