A Fully Coupled ALE Interface Tracking Method for Falling Film Gas Absorption over Discrete Walls

Liquid-gas mass transfer processes in falling films are simulated to study the characteristics of the wall configuration and film waviness for both water vapor and oxygen absorption. Special attention is paid to the relationship between the mass transfer and the flow behavior of the falling film over vertical solid and discrete walls. The influence of wave frequency on the interfacial mass transport is also investigated. A fully coupled arbitrary Lagrangian-Eulerian interface tracking algorithm is used to analyze the interfacial heat and mass transfer. The simulation results show that discrete wall increases the average Sh number by ۱۶.۱۲% for f = ۰ Hz and ۳۵% for f = ۹.۳ Hz compared to solid wall for LiBr-water solution. For oxygen absorption in water, the average Sh number for falling film over discrete wall increases up to ۲۰.۷۶% for f = ۰ Hz and ۱۱۲.۱% for f = ۱۵ Hz compared to solid wall. The discrete wall in water vapor absorption had some decreasing effects on mass absorption while it was enhancing for oxygen absorption problem. It is recommended to use discrete wall if film waviness is not possible.

Keywords:

Gas absorption , Discrete wall , Arbitrary Lagrangian-Eulerian (ALE) , Interface tracking method , Wavy falling film