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Mass-transfer enhancement by a reversible chemical reaction across the interface of a bubble rising under Stokes flow



Mass transfer around a bubble rising in a liquid under Stokes regime is investigated when a reversible chemical reaction, math formula, is taken into account. Four dimensionless parameters control the interfacial transfer rate: the Péclet and Damköhler numbers, the ratio of the diffusion coefficient of both species, and the reaction equilibrium constant. The mass-transfer equations are solved numerically with a finite element technique. A boundary layer approach is also proposed and solved with a coupled technique of finite difference and Chebyshev-spectral method. The equilibrium constant and the ratio of diffusion coefficients have a strong influence on the coupling between the chemical reaction and mass transfer leading to an increase of the Sherwood number. The interaction between the chemical reaction and advection is clearly established by the simulations. Conditions corresponding to Péclet number larger than the Damköhler number reduces the effect of the chemical reaction. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3376–3388, 2014