Mass Exchange Between Gases and Liquid Films

Mass Exchange Between Gases and Liquid Films 

Let us consider the absorption of weakly soluble gases on the free surface of a liquid film in a laminar flow on an inclined plane. It follows from the results of Section 1.3 that for moderate velocities of motion, the steady-state distribution of the velocity inside the film has the form of a semiparabola with maximum velocity 17max on the free surface, which is one and a half of the mean flow rate velocity (V)  

Here g is the gravitational acceleration, a the angle between the plane and the horizon, and h the film thickness, given by the expression 

The liquid velocity inside the film has a parabolic profile and is given by the formula 

Assume that in the cross-section X = 0, fluid flow contacts with a gas, so that constant concentration C = Cs of the absorbed component is attained on the free boundary (Y = 0), while no solute is contained in the irrigating liquid. Furthermore, we assume that there is no flow across the wall. We restrict ourselves to the case of high Peclet numbers, in which one can ignore the molecular diffusion along the film. 

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