Gas absorption in a sheared falling liquid film with chemical reaction: mass transfer and hydrodynamic stability

We study the general case of gas absorption with irreversible first-order chemical reaction in viscous liquid films that flow down the interior of two vertical walls and are sheared by a turbulent gas flow occupying the remaining region of the channel. An irreversible first-order reaction between the solute in the liquid and the wall is also considered. The stability of the two-phase system is investigated by solving the Orr--Sommerfeld equations for both the gas and liquid flows. The effects of various parameters on the concentration profiles of the solute in the liquid and gas phases have been analyzed. With enhanced reaction rate in the film, the mean liquid-phase concentration at the outlet decreases, while the absorption rate increases with increasing slope of the liquid concentration profile at the gas-liquid interface and the axial variation in the gas-phase concentration becomes higher. Numerical results also compare reasonably well with experiments from the literature. Finally, this study allows us to present suggestions on the absorption of carbon dioxide, which are important from a practical point of view.