The nozzles can be executed as a single-component nozzle, in which the water is aerosolized using high pressure (~ 35 bar), or as a two-component version, in which the water is aerosolized using compressed air.
A conditioning tower equipped with a spillback spray system and high-pressure centrifugal pump is designed to force water through a set of nozzles located inside the tower near the inlet. The water pressure energy is sufficient to overcome the water cohesion forces and produce a fine mist. When the gas volume is a small percentage of the design volume, less cooling water is required.
In the mechanical system the water pressure delivered to the nozzles is constant. The excess water (above the volume actually required for gas cooling) is drawn off through an electrically or pneumatically operated two-way control valve and a return pipe to the feeding water tank.
This valve is opened (or closed) to allow more (or less) water to flow back to the water tank and therefore controls the gas temperature.
When the return pipe is totally closed all the water is forced into the conditioning tower for maximum cooling effect.
In a dual media system (water + compressed air) the compressed air provides the energy to overcome the water cohesion and to produce a fine mist. Water at low pressure (about 3 bars) is mixed with compressed air directly in the nozzle.
In comparison with the spillback, this system is more efficient and produces smaller water particles. That reduces the required gas retention time in the tower, then its size.
In the dual media systems, less quantity of gas flow requires reduced cooling water volumes, the particles atomization is not detrimentally affected, since the specific compressed air consumption increases when the water volume decreases.