The key purpose of drift eliminators in evaporative cooling systems is to reduce (not eliminate as the name suggests) the escape of water droplets entrained in the discharge air stream of a cooling tower or evaporative condenser. In some projects, the clients also use the drift eliminator as an air louver. 

What is a Drift Eliminator?
A drift eliminator can be defined as equipment containing a complex system of baffles designed to minimize drift discharging from a cooling tower or evaporative condenser. Today they are predominantly manufactured using either PVC or polypropylene (PP) material although some towers may still have metal-type versions.

They are located on the discharge side of a cooling tower, either above the cooling tower heat transfer surface and distribution layer on a counterflow cooling tower or horizontally, in front of the heat transfer surface on a crossflow tower.