HEAT TRANSFER BETWEEN THE SURFACE OF A RIVER AND THE ATMOSPHERE
For cooling of power station with water from rivers the waste heat absorbed by the river is transported back into the atmosphere mainly by free convection, wind generated forced convection and by evaporation.
Heat and mass transfer coefficients between water and the atmosphere which are needed for calculating of the energy balances unfortunately are not very well known and scattering in a wide range, due to the fact that measurements in the free atmosphere usually cannot be made under steady state conditions.
In an effort to generate more reliable heat and mass transfer coefficients which depend on the meteorological data new measurements have been performed at a typical natural water. In these experiments the temperature change of the water between two control stations was determined under various meteorological conditions. The diurnal cycles of the meteorological and hydrological data provide the necessary informations for the calculation and representation of the heat and mass transfer coefficients. Simple power relations in the wind speed are communicated which correlate the data quite well. Based on these results it is possible to specify the diurnal cycles of the different heat fluxes, which cause cooling or heating effects of the water body by convection, evaporation and radiation.