Experimental and numerical investigation of solid particles thermal energy storage unit

A two-dimensional separate phases formulation is used to develop a numerical analysis of the transient response of a cylindrical packed bed thermal energy storage system, which is randomly packed with spheres having uniform sizes and encapsulated the paraffin wax as a phase change material (PCM), with air as a working fluid flowing through the bed. The fluid energy equation was transformed by finite difference approximation and solved by Alternating Direction Implicit scheme, while the PCM energy equation was solved using fully explicit scheme. This analysis is valid for fluids of various Prandtl numbers. It can be applied for both charging and recovery modes and for a broad range of Reynolds numbers. Measurements of both fluid and PCM temperature were conducted at different axial and radial positions and at different operating parameters. Experimental measurements of temperature distribution compare favorably with the numerical results over a broad range of Reynolds numbers.