Comparative efficiency evaluations of four types of cooling tower drift eliminator, by numerical investigation

Abstract

This work presents a comparative evaluation of the performance of four types of wave-plate drift eliminator commonly used in mechanical cooling towers, with similar morphology. The droplet collection efficiency and the coefficient of pressure drop are numerically calculated, for values of inlet velocity 1 ≤ U e ≤ 5 m / s and droplet diameter 2 ≤ D p ≤ 50 μ m , with Reynolds number and inertial parameter roughly in the ranges 650 ≤ Re ≤ 8500 and 0.05 ≤ P i ≤ 2.5 , respectively. The numerical model has been validated through comparisons with numerical and experimental results taken from the literature, including additional configurations of horizontal wave-plate mist separators. The effects of considering the turbulence dispersion of droplets are studied, as well as the influence of the inertial parameter and the aspect ratio of the eliminator sample channel. Best results are obtained by using the SST k − ω turbulence model, with values of non-dimensional scaled distance to wall y + comprised in the range 0.2–0.5, including the turbulent dispersion of droplets. A global correlation for the collection efficiency is proposed, as a function of the inertial parameter and the removal geometric parameter, which is introduced in this work. Finally, it is developed a procedure focused on establishing the overall efficiency for each type of eliminator, based in a key power function.