A model for seasonal and annual cooling tower impacts

Abstract

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 natural-draft cooling towers. The model typically requires five years of hourly surface meteorological data and concurrent twice-daily mixing heights in addition to basic data on the thermal performance of the cooling tower. The model predicts average plume length, rise, drift deposition, fogging, icing, and shadowing. The model uses a category scheme in which the five years of hourly surface data are placed into about 100 categories based on a special plume-scalling relationship. With this 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 merging patterns and of the wake effects from tower housings for different wind 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 the United States of America and Europe, an extensive database on cooling tower plumes and drift was accumulated and analysed to assist in the 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 are given for a representative natural-draft cooling tower installation and for a typical linear mechanical-draft cooling tower arrangement.