The aim of this work is to investigate of the evaporation from a horizontal free water surface under forced and free convection conditions. Experimental results were obtained in an installation consisting of a low speed wind tunnel and an evaporation tank. The status of free convection was provided at different temperature and relative humidity values of the ambient air. By changing the DC fan voltage, forced convection was ensured. Flows with Reynolds numbers varying between 6274 and 12667 were considered. Using the full factorial design which is a kind of design of experiment, relationship between evaporation rate and affecting parameters such as air flow velocity, air temperature and relative humidity were examined. Finally, an empirical correlation was derived by the experimental results. To validate the mathematical model were compared experimental measurements for the mass transfer at the free water surface and with available correlations in literature.
Evaporation rates calculated with obtained empirical correlation were compared with the values obtained by experimental results, it is observed that the calculated evaporation rates are within an error band of ±20%. The experimental results compared to the available correlations individually, a better level of agreement was obtained.