CONVECTIVE-DIFFUSIVE HEAT-TRANSFER IN A PACKED-BED WITH CONSTANT HEAT-FLUX AT THE WALL - AN ASYMPTOTIC SOLUTION FOR XI-] LARGE

Packed-bed systems with axial convective, radial diffusive heat transf er and with a constant heat flux at the wall are studied. Asymptotic s olutions valid for axial distances sufficiently away from the inlet po sition of the packed-bed are presented and their behavior investigated . Two geometrical configurations (i.e., the parallel plate and the cyl indrical tube) are analyzed. Also, lower bounds for the axial coordina te are derived and their effect on the validity of the asymptotic solu tion are investigated. The asymptotic temperature profile is shown to yield the correct bulk temperature profile and to predict the correct Nusselt number for both types of geometries.