Investigation of water vapour absorption into wavy falling films by developing a fully coupled interface tracking finite volume method

Abstract

Steady and unsteady two-phase gas-liquid flows are simulated to investigate the absorption characteristics of LiBr falling film. A fully coupled arbitrary Lagrangian-Eulerian interface tracking (ALE-IT) algorithm is developed to calculate transient interfacial heat and mass transfer. The accuracy of numerical solution assessed through detailed comparisons with previous works. The influence of the solitary and capillary waves are investigated on the interfacial heat and mass transfer and compared with those in a falling film. The local Sherwood number (Sh) is calculated and related to the dynamic structure of the wavy interface. Also, the effects of Reynolds number (Re), Strouhal number (St), and liquid side wall temperature are studied on the absorption rate. It is shown that, cooling the wall temperature increase the absorption rate and the highest heat and mass transfer are estimated across the interface at St =0.03. The dynamic structures of the interface instabilities in terms of solitary and capillary waves play a crucial role on the absorption rate. An absorption enhancement is observed adjacent to the capillary interface waves while the absorbent flux is suppressed with in solitary waves.