Two-phase flow dynamics affects several industrial processes and technologies. In the chemical industry, the capture of carbon dioxide through absorption units relies upon the interaction between a thin liquid film and the flue gas. These two phases flow in a counter-current fashion, resulting that the interface might be disturbed with occurrence of waves. The waviness of the interface increases the interacting area and enhances the mass transfer between the two phases, e.g. more CO2 is absorbed into the liquid. In addition, if the phases are reactive, and this is often the case of absorption and distillation technologies, the chemical reactions at the gas-liquid interface also influence the mass transfer rate.

In this work, we investigate the absorption of carbon dioxide into an aqueous solution of monoethanolamine. The experimental set-up consists of an inclined channel where a thin film falling under the action of gravity is sheared by a counter-current gas flow driven by an applied pressure gradient. Through titration of samples, we measure the absorption occurring at different flow conditions, by varying the liquid flow rate, the gas speed and its composition, as well as the pressure inside the channel. It is observed that an increase of the liquid load leads to a decrease of the absorption rate, whereas when the gas speed is increased, so does the absorption rate. Interestingly, the amount of CO2 absorbed into the liquid is not affected by the CO2 starting concentration of the solvent, at least until saturation is reached.

Aiming to support the experimental results with numerical simulations, we implement a novel module for mass transfer in our level-set flow solver taking into account a variant of the ghost-fluid formalism. Our in-house flow solver applies the level-set method along with a continuous surface-tension model; it is also developed to run on super-computer through distributed or shared-memory architecture. The hydrodynamics module of this flow solver has been already validated against linear and non-linear theory, as well as experiments. With the implementation of the mass-transfer module, we validate the scenarios with and without hydrodynamics by comparing the species concentration in the bulk flow to the analytical solution. In a final stage, we implement the chemical reaction numerical module to perform analysis of the absorption rate in reactive flows, and try to reproduce the above-mentioned experimental results in order to explore the active role of the waves at the interface.