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This paper investigates the ability of two widely used evaporation models: Dalton based correlations and similarity theory results by comparing with experimental measurements. A series of experimental investigations are carried out over a wide range of water temperatures and air velocities for 0.01 B Gr/Re 2 B 100 in a rectangular heated pool. The results show that for forced convection regime satisfactory results can be achieved by using the modified Dalton correlations, while, due to ripples appear on the water free surface, similarity theory under predicts the evaporation rate. In the free convection regime, Dalton based correlations even with modification are not able to predict acceptable results. For mixed convection regime, although both the similarity theory and Dalton based correlations without modification are not able to predict the mild non-linearity behavior between water evaporation rate and vapor pressure difference, but they obtain relatively satisfactory results. A dimensionless correlation using the experimental data of all convection regimes is proposed to cover different water surface geometries and air flow conditions. List of symbolsD H 2 o;Air Binary mass diffusion coefficient m 2 /s D h Hydraulic diameter of rectangular duct (m) g Gravitational acceleration m/s 2 g m;H 2 o Mass transfer coefficient Gr Mass transfer Grashof number H Height of rectangular duct (m) h fg Enthalpy of vaporization (J/kg) k Thermal conductivity w/mk L Length of water pan (m) _ m e Evaporation rate of water kg/m 2 h m f H 2 o

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