A MODEL FOR SEASONAL AND ANNUAL COOLING-TOWER IMPACTS

The Argonne National Laboratory/University of Illinois Seasonal/Annual Cooling Tower Impacts model provides predictions of seasonal, monthly , and annual cooling tower impacts from any number of mechanical- or n atural-draft cooling towers. The model typically requires five years o f hourly surface meteorological data and concurrent twice-daily mixing heights in addition to basic data on the thermal performance of the c ooling tower. The model predicts average plume length, rise, drift dep osition, fogging, icing, and shadowing. The model uses a category sche me in which the five years of hourly surface data are placed into abou t 100 categories based on a special plume-scaling relationship. With t his reduced number of cases to be run for long-term impact evaluations , advanced state-of-the-art models for plume impacts are then applied. For multiple plumes, the methodology includes variation of the mergin g patterns and of the wake effects from tower housings for different w ind directions. The main advantage to this model over previous models is its advanced theoretical development and extensive model validation with experimental data for its component submodels. From studies in t he United States of America and Europe, an extensive database on cooli ng tower plumes and drift was accumulated and analysed to assist in th e identification of superior theoretical assumptions. Other data, not used in model development, provided for independent model verification . The validation of each submodel is presented, and typical results ar e given for a representative natural-draft cooling tower installation and for a typical linear mechanical-draft cooling tower arrangement.