Environmental Engineering Reference
the renewed air and the contamination risks are avoided (“useful” airflow does not come into
contact with the water that has been cooled evaporatively).
The mixed systems are a combination of direct and indirect systems, using sequential
modules in order to improve the performance and increase their utility in wet climates. Other
possibilities are heating exchange batteries and classical cooling systems.
As aforementioned, the evaporative systems can be considered as heat recoverers when
they use, as secondary air, the air provided by the conditioned premises, or just a mixture of
this air and outdoor air. These configurations are called regenerative or recoverable based on
the following explanations:
Indirect Regenerative Evaporative System : this is an Indirect Evaporative Cooler
where a percentage of the primary airstream is used as a secondary airstream, which allows an
increase in the cooling effect (Figure 1).
Figure 1. Indirect Regenerative Evaporative System.
Indirect Evaporative System with a Returning Air Recovery Configuration: this is an
Indirect Evaporative Cooler where the air that comes from the installation is used as a
secondary airstream. This is the configuration which we have used (Figure 2).
Figure 2. Indirect Evaporative System with a Returning Air Recovery Configuration.