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Summary In this work, a numerical model of a vertical cylindrical packed bed latent heat thermal energy storage (PBTES) system filled with cylindrical‐shaped encapsulations is developed. Two energy equations with a non‐equilibrium heat transfer model are employed to analyze the transient variation of heat transfer fluid (HTF) and encapsulated phase change material (PCM) considering the filler material as a porous medium. An enthalpy‐porosity technique is used to model the melting and solidification of PCM inside the capsule. The effects of the shape of the encapsulation, the aspect ratio of cylindrical encapsulation, the porosity of the storage system, HTF flow rate and encapsulation material are studied using the validated numerical model. For the same volume of encapsulation, the heat transfer rate and the thermal efficiency are found to be higher for the spherical encapsulation as compared to the cylindrical encapsulation. The thermal efficiency and the heat transfer rate of the storage system increase with the increase in the aspect ratio of the encapsulated PCM cylinder. With an increasing flow rate of HTF through the packed bed, the heat transfer rate and thermal efficiency improve. The PBTES with higher thermal conductive encapsulation material is more efficient and has a higher HTF temperature at the outlet during the discharging operations. The stabilization factor (SF) is introduced to assess the stabilization performance of the PBTES. The SF is lowest for the cylindrical encapsulation of aspect ratio of 4/3, the porosity of bed of 0.33 and the lowest HTF flow rate of 7.05 L/min considered in this study.

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