Surface-to-bed heat transfer in fluidised beds: Effect of surface shape

In recent times, the possible application of fluidisation technologies to the surface treatments of engineering materials becomes a subject of growing interest both for manufacturing and chemical industries. Heat and mass transfer rates between the surface and the fluidised bed strongly influence the performance of the surface treatment. Experimental results of heat transfer between a submerged surface and a fluidised bed are presented in this article. This work is focused on the influence of bed material properties and surface geometry on heat transfer coefficient. Experimental tests show that the heat transfer coefficient is notably affected by the shape of the immersed surface resulting higher for surfaces with better aerodynamic shape. An interpretative model, based on the dimensional analysis, has been used for the description of the experimental results.

Heat transfer between submerged surfaces and a fluidised bed has been studied. Heat transfer coefficient depends on surface shape, resulting higher for more aerodynamic ones. Moreover, it is independent on particle thermal conductivity. A dimensional model is able to describe the experimental data by a shape factor, H/Deq, which accounts for the different fluid dynamic fields around the exchange surface.Figure optionsDownload as PowerPoint slide