Heat Transfer Coefficient Prediction for Falling Film Evaporation Used for Solvent Removal from Highly Viscous Liquids

The paper deals with the mixture effect correction for falling film evaporation of solutions containing dissolved solids. It is shown that the correction arises from vapour-liquid equilibrium effects similar to those observed for boiling of multi-component liquid mixtures. The predictive method reported here uses the HTFS correlation 1 to obtain the heat transfer coefficient for the highly viscous equivalent pure fluid, and then applies a mixture effect correction to it. Data for falling film evaporation from aqueous solutions of polyethylene glycol are predicted reasonably well by the method.