Comparative evaluation of cooling tower drift eliminator performance

Abstract

The performance of standard industrial evaporative cooling tower drift eliminators is analyzed using experiments and numerical simulations. The experiments measure the droplet size spectra at the inlet and outlet of the eliminator with a laser light scattering technique. From these measured spectra, the collection efficiency is deduced as a function of droplet size. The numerical simulations use the computer code SOLASUR as a subroutine of the computer code DRIFT to calculate the two-dimensional laminar flow velocity field and pressure drop in a drift eliminator. The SOLASUR subroutine sets up either no-slip or freeslip boundary conditions at the rigid eliminator boundaries. This flow field is used by the main program to calculate the eliminator collection efficiency by performing trajectory calculations for droplets of a given size with a fourth-order Runge-Kutta Numerical method. The experimental results are in good agreement with the collection efficiencies calculated with no-slip boundary conditions. The pressure drop data for the eliminators is measured with an electronic manometer. There is good agreement between the measured and calculated pressure losses. The results show that both particle collection efficiency and pressure loss increase as the eliminator geometry becomes more complex, and as the flowrate through the eliminator increases.