Heat transfer across evaporating falling films of single component liquids

Heat transfer in single component falling liquid films undergoing surface evaporation was studied experimentally and theoretically with emphasis on extending the data base to Prandtl numbers larger than those in the existing studies. Experiments were conducted to measure heat transfer coefficients of evaporation for two test fluids: water and propylene glycol. The new data considerably extended the previously existing data base by increasing the range of Prandtl number by about an order of magnitude. Comparison with the well known Chun and Seban correlation indicated that the correlation is inadequate for fluids with Prandtl numbers larger than about 5. Improved correlations were proposed. In the wavy laminar region, the dimensionless heat transfer coefficient correlated well with Reynolds and Kapitza numbers. In the fully turbulent region, a semi-empirical correlation based on a turbulence model capable of representing data quite well at all Prandtl numbers was developed.