Evaluation of mathematical models for natural-draft cooling-tower plume dispersion

Air Pollution Modeling

“…The fundamental nondimensional parameters that govern the dispersion of natural-draft cooling tower (NDCT) plumes are (Carhart et aI., 1982) • the initial densimetric Froude number Fa' where where Wo is the top exit velocity, U a is the wind speed at the tower top, d is the tower exit diameter, Oa is the ambient potential temperature, Qa and Qa are, respectively, the tower exit density and ambient density at the tower top (including moisture effects), and qa' qa are the exit plume and ambient specific humidities, respectively. Carhart et al (1982) provide an evaluation of the theory and actual performance of 16 models commonly used for the prediction of plume rise from natural draft cooling towers. The best models can predict visible plume rise within a factor of two and visible plume length within a factor of 2.5, but only for 50 percent of the cases tested.…”

Microphysical Measurements of Fog Formed in a Turbulent Jet

“…Bennett (1971) investigated the evaporating region by comparing the spatial dimensions of the visible plume with those predicted by an equilibrium-continua model. In this model, as in the state-of-the-art cooling tower plume models (Carhart et al, 1982), the theoretical fog boundaries are defined as those that delineate supersaturated and unsaturated regions in space.…”