Evaporative Cooling Systems

Performance depends primarily on air temperature, relative humidity, and wet-bulb temperature, which represents the theoretical cooling limit that can be achieved. Altitude, thermal variations throughout the year, and surrounding obstructions also affect efficiency.

An evaporative condenser condenses the refrigerant gas inside coils that are wetted by sprayed water and cooled by an airflow. According to the evaporative cooling principle, when a small portion of water evaporates, heat is dissipated and the refrigerant condenses.

Both open-circuit and closed-circuit towers exploit a very efficient operating principle: forced evaporation of a minimum amount of water causes a lowering of the temperature of the main water mass.

In direct evaporative cooling (open-circuit evaporative tower), the process water to be cooled is introduced into the tower and comes into direct contact with the outside air. The water evaporates directly into the air, removing heat and lowering its temperature — leveraging a simple natural principle: the forced evaporation of a small amount of water causes a temperature drop in the main water mass.

Les condenseurs évaporatifs fonctionnent de la même manière que les tours de refroidissement en circuit fermé. La seule différence réside dans le fluide de traitement, qui est un gaz réfrigérant.

Wet cooling towers are known for their high energy and thermal efficiency, making them an ideal solution for dissipating excess heat in air-conditioning systems and industrial processes. Thanks to the principle of evaporative cooling, these technologies can achieve very low cooling temperatures while using minimal electrical energy and water. In many applications, these lower temperatures allow the overall system to operate with reduced power consumption, directly contributing to energy savings and a lower environmental impact.

All evaporative cooling systems use the evaporation of a small amount of water to lower the temperature of the larger mass of water. There are three main types of evaporative cooling systems: open circuit cooling towers, closed circuit cooling towers, and evaporative condensers.

Ambient air is the heat-transfer medium that enables water evaporation and thermal exchange. Its temperature and relative humidity determine the efficiency of the process: under dry-air conditions, the evaporative effect is at its maximum.

Both systems use water, but in different amounts, in different ways, and with different levels of efficiency. The direct evaporative

In summary: high cooling efficiency, low operating costs, and others related to the operation of the technology.

Modern evaporative coolers use automatic blowdown systems controlled by conductivity sensors, partial recovery of discharge water, and optimized make-up strategies. Adiabatic systems, on the other hand—with the proper use of sensors and PLC-based parameter settings—use water only during periods of maximum thermal load, reducing overall consumption compared to traditional cooling towers (though with some loss of efficiency). The adoption of recovery circuits also allows part of the water to be reused in any cooling system that relies on this resource.

Wherever there is a process fluid to be cooled, up to a temperature of a few degrees above the wet bulb temperature of air, an evaporative cooling system can be used.

In an evaporative system, approximately 2% of the mass to be cooled evaporates and is released back into the environment.

The approach to the wet-bulb temperature is the difference between the leaving water temperature (or water–glycol mixture) and the air’s wet-bulb temperature. The smaller this difference, the higher the cooling tower’s efficiency.

During the design phase, the use of selection and configuration software makes it possible to compare different solutions—chillers, cooling towers, adiabatic coolers, or dry coolers—by simulating their seasonal performance and heat loads. These digital tools also estimate energy and water consumption and help optimize system sizing.