Transient heat transfer by free convection in a packed bed of spheres: Comparison between two modelling approaches and experimental results

Two modelling approaches of transient heat transfer by free convection in a packed bed of spheres are carried out and then, compared with experimental results. The first approach uses computational fluid dynamics software which directly solves the NavierStokes equations and the local energy equations in the fluid and solid phases. It also includes radiation between the solid surfaces. The second approach, developed by the authors, uses methods developed for porous media and packed beds. The heat transfer model, based on a dispersed particle approach, takes into account air-particle convection, conduction and radiation between particles and 1-D-conduction inside the particles. The numerical results obtained using the two approaches are in good agreement with the experimental values of air and particle temperature for a particular free convection configuration.