Review and evaluation of models estimating the minimum atmospheric dilution of gases exhausted near buildings

Abstract

In this study, eleven mathematical models estimating the minimum possible atmospheric dilution of rooftop exhaust gases around buildings are evaluated and reviewed using data obtained from 72 full-scale tracer tests at two buildings. Quantities measured were the stack height, stack-to-intake distance, stack diameter, wind speed and direction, exhaust flux, and the stack-to-intake dilution. These models are all based on wind-tunnel simulations and are designed to account for a worst-case scenario so that they can be used to provide a conservative safeguard for design of new stacks or for modification purposes. Although none of the models gave outstanding performance relative to the others, Halitsky’s model, derived from the prism tests and Clinical Center data incorporating the exhaust momentum ratio, gave particularly good predictions. Further, all models led to very conservative estimates of the dilution in the case of gases exhausted close to a receptor, suggesting that the models reviewed here should not be used in such cases. © 1995 Taylor & Francis Group, LLC.