Estimating Forced Evaporation from Cooling Ponds

Forced evaporation from cooling ponds can be estimated with reasonable accuracy from readily available information. The only data needed are the amount of heat added by the plant, and air temperature and wind speed recorded at the nearest weather station. The heat added by a power plant is disposed of principally by increased evaporation and by increases in back radiation and conduction of heat to the atmosphere. The relationships among the variables are mathematically somewhat complicated, so that a graphical solution is presented for simplification. For a selected water-surface temperature and wind speed, the graph gives the percentage of heat added by the plant that is used in increasing evaporation. The plant operator can then, if desired, easily compute the actual volume of forced evaporation.