Dimensionless Evaporation Rate from Free Water Surface at Tubular Artificial Flow

Besides building services employments and swimming pools there are many industrial facilities with free surface water reservoir for different technological purposes. On the free surface heat transfer and diffusion occur, whereby the vapour diffuses into the ambient air. Therefore, the water loss should be replaced. There are many empirical correlations for calculating the quantity of evaporated water which methods largely differ from each other. The evaporation rate can be varied depending on attendance of clear humidity-based driving forces between gas and liquid or in addition attendance of temperature-based driving forces too. At the literary models another problem is that different correlations should be used depending on the temperature and velocity of ambient air and the temperature of the evaporating liquid. Furthermore the range of interpretation of these correlations in many cases is often not known. In our work dimensionless equations will be described the evaporation rate for natural and forced convection taking into account the direction of the two driving forces.