Water and air, these two elements have been used by mankind for thousands of years to improve their lives. Moreover, thanks to intelligent research and applications, these two natural elements have learned to live together influencing the evolution of humanity itself.
In fact, from prehistoric times to the present day, mankind has tried to exploit the capabilities of these two elements in every way possible; for example, by compressing them and mixing them, hence, allowing to use these characteristics in the fundamental processes of transformation.
The following diagram is an example of what happens in cooling towers when water is cooled by air:
Heating and cooling temperature domain systems were amongst the first applications to be used. These methods were based on the water evaporation phenomenon. The principle is still used today for making cooling tower function.
Other applications include electric power plants, industrial plants, greenhouses for agriculture, mining, etc.; but, often there is the problem of how to dispose of unused heat. In most cases this heat is disposed with water taken from rivers, sea, lakes.
Until a few decades ago, the heated water was taken back to the supply source. This approach caused an environmental impact too great for the community and, furthermore, considerable waste of energy. So, the concern was how to dissipate the heat without causing environmental damage and violating existing laws. This was a major issue in the industry world. What to do?
There were two alternatives:
(i) First, adopting a cooling “dry” system, for which it is necessary to use large quantities of air. In case of large plants, this would mean moving huge volumes of air with subsequent construction of complex surfaces for the exchange of heat.
(ii) Second, adopting a cooling “water” system that uses a mixture of air and water. The cooling water circulates in the system absorbing the heat. Hence, sent in cooling towers, it will come in contact with the air and, as a consequence, it cools down through evaporation (mass transfer).
A cooling tower is an indispensable device for a lot of industries. In fact, they are the most economical solution because, thanks to water recycling, they allow for a low cost capital investment. This is precisely the reason why the tower plays an important and challenging role for obtaining an efficient cooling tower that is most economical.
The most important component of the cooling tower is the filling material, because it’s decisive when it comes to increasing the contact surface and, hence, increasing the heat exchange interface between the two elements, air and water. Thus, having a good filler material means improving the performance of the same tower.