An open cooling tower is a heat exchanger that in order to cool down water makes use of the direct contact with the air. The heat transfer occurs partially thanks to a heat exchange between air and water, but mainly thanks to the evaporation of a small quantity of the water that needs to be cooled. This will allow to cool down to a temperature lower than the ambient temperature.

Operation

The water that needs to be cooled will be directed to the upper part of the cooling tower.

The nozzles (A) distribute water over the tower packing (B).

Water will be spread in a thin and even film over the packing thanks to its shape. This will result in a very large contact surface (heat exchange surface).

The fan blows or extracts (depending on the type of fan) ambient air through the packing. This air will cool the water in 2 different ways. Part of the heat will be removed due to convection (contact between hot water and colder air), but the main cooling part will be because of evaporation.

The air, which is now saturated with humidity, will be exhausted through the upper part.

The cooled down water will be gathered in the basin (C) so it can be reused in the production process.

The drop eliminators above the nozzles make sure that the water drops don't leave the cooling tower.