Numerical investigation of heat transfer mechanism in a vertical shell and tube latent heat energy storage system

• Convection and conduction effect in phase change energy storage systems was studied.
• The simulation models were validated using experimental data.
• A combined convection-conduction model could better describe heat transfer in storage systems.
• Convective heat transfer showed a large influence during melting processes.
• Heat transfer during solidification processes was dominated by thermal conduction.

The thermal behavior and heat transfer characteristics of a vertical cylindrical shell and tube latent heat thermal energy storage (LHTES) unit are investigated using a pure thermal conduction model and a combined conduction-convection heat transfer model, respectively. The results from numerical simulation are validated with published experimental data which indicate that the combined convection and conduction model can better describe the energy transfer in the phase change materials (PCMs) during melting process. In contrast, heat transfer by conduction is more significant during the solidification process. In terms of total solidification time, the two models show little difference.