Numerical modeling of the drift and deposition of droplets emitted by mechanical cooling towers on buildings and its experimental validation

摘要

A CFD numerical modeling for simulating the drift emitted by mechanical cooling towers located in built-up urban areas is presented. The averaged Navier-Stokes equations for the air motion are discretized through a finite volume method, with the κ-ε model to simulate the turbulent flow. An appropriate set of boundary conditions is employed, in order to avoid the non-homogeneity problem in the Atmospheric Boundary Layer (ABL). A Eulerian-Lagrangian model is used to simulate the air-water droplet motion, taking into account the effects of evaporation. The results are validated with experimental data of the deposition of droplets emitted by a pilot cooling tower, obtained through a technique based on water sensitive papers. Local meteorological data are measured through a meteorological tower adjacent to the cooling tower. The present study shows the influence of variables such as the ambient dry bulb temperature, the ambient specific humidity and the droplet exit temperature from cooling tower on the water droplet deposition and on the size of the affected area for mechanical cooling towers. The numerical procedure has proved useful for obtaining the outlined objectives.