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Mass transfer and dispersion around active sphere buried in a packed bed
Author(s) -
de Carvalho João R. F. Guedes,
Alves Manuel A. M.
Publication year - 1999
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690451205
Subject(s) - péclet number , mass transfer , sherwood number , dispersion (optics) , mechanics , advection , diffusion , spheres , packed bed , molecular diffusion , stagnation point , convection , range (aeronautics) , chemistry , thermodynamics , physics , materials science , heat transfer , reynolds number , chromatography , turbulence , optics , nusselt number , metric (unit) , operations management , astronomy , economics , composite material
Mass transfer around single spheres in granular beds of inerts (packed or fluidized) was analyzed for transport by advection and diffusion/dispersion. Fluid flow in the granular bed around the spheres was assumed to follow Darcy's law; at each point, dispersion of solute was assumed to be determined by the coefficients of transverse and longitudinal dispersion, respectively, in the cross‐stream and streamwise directions. The elliptic equation resulting from a differential mass balance was solved numerically over a wide range of the relevant parameters. Resulting values of the Sherwood number are represented accurately by the product of two terms: the solution for advection plus molecular diffusion, which depends only on the Peclet number relative to the active sphere; the enhancement brought about by convective dispersion, which depends only on the Peclet number relative to the inert particles.