Comparison of thermal storage characteristics of phase change materials encapsulated in different capsule configurations (original) (raw)

This paper presents the thermal modelling and performance comparison of latent heat based thermal energy storage (TES) systems using phase change materials (PCMs) encapsulated in containers of different geometrical configurations. The latent heat storage (LHS) module considered here is a capsule containing sodium nitrate PCM which exchanges heat with the source material. Effective heat capacity method is employed to account the latent heat of the PCM. Boussinesq approximation and Darcy law's source term add added in the momentum equation to incorporate the natural convection of molten PCM and nullify the velocities of solid PCM. The equations of the 2-D axi-symmetric model are solved using COMSOL Multiphysics. Melting time of LHS capsules in four different configurations viz., spherical and cylindrical (H = D, H = 4D and H = 8D) are compared. The thermal characteristics are compared using isothermal contour plots and temperature-time curves.