The influence of the Henry number on the conjugate mass transfer from a sphere: II – mass transfer accompanied by a first-order chemical reaction

 Conjugate mass transfer between a sphere and a surrounding fluid flow in the presence of an isothermal, first-order irreversible chemical reaction occurring either in the continuous or in the dispersed phase has been analysed. Two sphere models, the sphere with rigid interface and the sphere with mobile interface and internal circulation, have been studied. Creeping flow is assumed. The mass balance equations were solved numerically. The influence of the Henry number (H) and diffusivity ratio (Φ_D)(0.01≤H(Φ_D)≤100) is studied at intermediate Pe numbers (Pe = 100) and slow, intermediate and fast chemical reaction. The present results, expressed by fractional Sh numbers, overall Sh numbers and enhancement factor, are compared with those provided by film and boundary layer theories. It is shown that, in the parametric space (Da, H, Φ_D), the film and boundary layer results acceptably approximate only locally the results obtained in this study. Received on 11 December 2000 / Published online: 29 November 2001