Transient gas-liquid mass transfer model for liquid films on structured packings

In this work a model is presented which describes the mass transfer through thin liquid films present on structured packings. The model has been derived for two cases: the absorption (or desorption) of a gaseous component into the liquid film and the transfer of the gaseous component through the liquid film to the packing surface where an infinitely fast reaction takes place. These cases have been solved for three bubble geometries: rectangular, cylindrical, and spherical. For Fourier numbers below 0.3, the model corresponds to Higbie's penetration theory for both cases. The Sherwood numbers for cylindrical and spherical bubbles are 20% and 35% higher, respectively, than for rectangular bubbles. In case of absorption and Fourier numbers exceeding 3, the effect of bubble geometry becomes more pronounced. The Sherwood numbers for cylindrical and spherical bubbles now are 55% and 100% higher, respectively, than for rectangular bubbles. In case of infinitely fast reaction at the packing surface, the Sherwood number corresponds to Whitman's film theory (Sh = 1) for all bubble geometries. The model data has also been fitted to engineering correlations. The obtained correlations describe the model with a maximum error less than 4%.