(622c) Teaching Classical Gas-Liquid Mass Transfer Models Using Multi-Physics Software

In this presentation, the sensitivities of the classical gas-liquid mass transfer models, i.e., the film theory, the penetration theory and the film-penetration theory, are compared with respect to the results of CFD simulations in a microfluidic domain. COMSOL® platform was used for CFD simulations.  Two examples will be presented. The first example will demonstrate the inability of penetration theory to explain the phenomena at microscopic level.  Due to large Fourier numbers in microfluidic domain, penetration theory fails.  The second example will demonstrate how the two film theory depends on hydrodynamics.  The film coefficients measured in double stirred tank reactors hardly reflect the reality.  The real cases exhibit strong variations in concentrations both with respect to time and position in multiphase contactors. Furthermore, the film interface is not flat.  Therefore, the accuracy of the predictions is still based on the empirical information averaged over the whole contactor geometry. Comparisons with the numerical simulations solving the species conservation equations (and in some cases also the equation of motion) using COMSOL® platform clearly reveals the limitations of the existing theories. This presentation intends to provide two examples for (under)graduate chemical engineering curriculum for teaching mass transfer using multi-physics software, hinting to the need for better theories of mass transfer.