Experimental Studies of Heat and Mass Transfer in Fixed Beds - 3

ur recent research at WPI has concentrated on the use of computational fluid dynamics calculations to solve for the steady-state 3D flow fields in model fixed beds, with associated heat transfer. The role of the experimental program lately has been to provide data that can be used to check the simulation results. We carried out validation studies [Nijemeisland, M. and Dixon, A.G., 1999; Nijemeisland, M. and Dixon, A.G., 2001] to compare the CFD simulations directly to experimental data. A packed bed of spheres with N = 2 was chosen, as this specific ratio allowed for a very structured bed in which the positions of all spheres could be known precisely. This specific geometry was used for an experimental setup and for the CFD simulations. Standard heat transfer experiments were carried out which gave radial temperature profiles.

Numerical simulations were performed under similar conditions to those under which the experiments were performed. The CFD simulations gave 3D axial, radial and tangential velocity fields, as well as the 3D temperature field. From these we could get pictures of the flow and of the temperature contours, like the ones shown here.

In a range of Reynolds numbers (373-1922) radial temperature profiles above the bed were extracted from the simulation results, and these were directly compared with experimentally obtained radial temperature profiles, both simulation and experimental temperature profiles were acquired at steady state conditions. The comparison of the temperature profiles (an example is shown in the figure) showed that CFD could qualitatively and quantitatively predict experimental results accurately.