Model Tests with Thin Sheets to Reduce Evaporation

Laboratory physical studies have been used to determine the evaporation coefficient for a circular sheet such as a physically separate barrier suspended over the water surface. The circular sheets that were studied in the laboratory had diameters ranging from 144–300 mm. During the experiments a recently developed evaporation measuring method, as well as device, was used. The measuring method is based on the replacement of the evaporated water, the water level being measured with special electrical equipment. For the calculations of the reduction effect, evaporation measurement data of two pans were used, one with an open water surface, and the other with a circular sheet above the water surface, carrying out these measurements simultaneously. Equations of evaporation reduction influence curves for both circular sheets were determined and the characteristic curve for the circular sheet was designed.