Heat and mass transfer in non-isothermal absorption of gases in falling liquid films Part II: Theoretical description and numerical calculation of turbulent falling film heat and mass transfer

Abstract

A mixing length turbulence model is presented, which was used for the numerical calculation of turbulent falling film heat and mass transfer coefficients. Numerous proposals of different authors for the prediction of eddy transport coefficients are discussed. Good agreement between calculated heat and mass transport coefficients and experimental data was achieved by the combination of Hubbard, Mills and Chung's proposal for the calculation of eddy transport near the film surface with a modified form of van Driest's, the latter being for the eddy transport near the solid wall. Furthermore, the dependence of the turbulent falling film heat transfer coefficients on the Prandtl number is discussed. It is shown that, besides the Prandtl number, a further dimensionless group must be considered in order to describe the effect of liquid properties on heat transfer.