Mass transfer into liquid falling film in straight and helically coiled tubes

Helically moving liquid films are principally used in many heat and mass transfer processes, which are usually practiced to minimize longitudinal dispersion, maximize secondary currents and provide compact spacing. In the present work, practical experiments are carried out to determine mass transfer coefficients for thin films of liquid falling in case of straight and coiled tubes. The system used in the present investigation is the absorption of CO2 into liquid films of distilled water, or ethyl alcohol (96.25%), or ethylene glycol of 12% or 5.2%. The obtained experimental results indicated higher mass transfer coefficient in the helically liquid film. Empirical correlations are concluded by using dimensional analysis method. The correlations relate Sherwood number to the following dimensionless groups for laminar and turbulent regimes. Sh=f(Ref,Sc,Gaf) forinclinedstraighttube Sh=f(Def,Sc,Gaf) forhelicallycoiledtube where Def, Gaf and Ref are Dean, Gallileo and Reynolds numbers for flowing films, respectively. While Sc and Sh are Schmidt and Sherwood numbers.