Mass transfer in liquid films during absorption Part III. Dependence of the liquid-side mass transfer coefficient on the molecular diffusivity of gases at high values of the schmidt number

Abstract

New experimental values of the liquid-side mass transfer coefficient k L were obtained for the absorption of helium, nitrogen and propane into a film of a highly viscous aqueous solution of ethylene glycol (kinematic viscosity v = 1.4 × 10 m 2 s −1), flowing down the vertical surface of an expanded metal sheet and down a smooth wetted wall. The purpose of the experiments performed in the range of Reynolds numbers 8 < Re < 70 and of Schmidt numbers 5800 < Sc < 75700 was to study the mass transfer mechanism at the gas-liquid interface by the experimental determination of the value of exponent m in the relationship between k L and the molecular diffusivity of a gas, k L ≈ D m . In the case of a smooth wetted wall the mean value of the exponent was close to 0.5 and the results were interpreted by the surface renewal model. In the case of an expanded metal sheet the mean value of the exponent was m = 0.64 and the film-penetration model was the most suitable for the interpretation of the experimental results.