FAQ on evaporative cooling

It is a heat exchange between air and water that causes partial evaporation of the water and a consequent cooling of the air. Since the phenomenon occurs on the contact surface between these two elements, the efficiency of the heat exchange is greater the larger the contact surface between them. A tangible example of the effects of this phenomenon is the cool breeze we can feel on the shores of a body of water, where there is a continuous heat exchange that lowers the air temperature.

Because it achieves an excellent balance between benefits and costs, regarding both the installation and its operation and maintenance.

With an evaporative cooling system, it is possible to recreate the conditions to maximize the natural air-water heat exchange and produce a significant flow of fresh air to be introduced into the rooms to be cooled. Through an "ad hoc" designed ducting system, it is then possible to guarantee conditions of maximum fluid mixing and targeted air distribution in hot environments.

The two systems are not comparable from a performance standpoint. A chiller makes thermal energy available in the form of water or refrigerant fluid at a low temperature, and external environmental conditions only partially influence the "amount of cold produced."

The performance of an evaporative cooling system, however, is directly correlated to the thermo-hygrometric conditions of the external air. In this case, the energy consumption remains constant and extremely low throughout the entire operating range, while the "amount of cold produced" can vary depending on the climatic conditions.

An adiabatic cooling system is ideal for reducing the sensible heat load of medium-to-large environments. Although in certain situations it may not reach performance levels comparable to those of a climate control system with a chiller, the benefit in terms of comfort is still significant and energy costs are decidedly lower.

By virtue of the extremely low energy requirement, such a system is the ideal compromise to maintain thermo-hygrometric comfort conditions in line with the needs of a production environment throughout the summer season.

As previously seen, the system operates thanks to the heat exchange that occurs between air and water. Air movement occurs through the use of one or more fans that draw in external air, allow it to pass through the water-laden evaporative panels, and convey it to a ducted distribution system. The electrical requirement of the fans therefore constitutes the primary consumption of the system. For this reason, fans with specific fluid-dynamic characteristics and a multi-speed regulation system have been used to further limit absorption. Other elements such as the pump, valves, and ozone generator result in practically negligible consumption, which can be further reduced in "free-cooling" operating mode (water intake pump inactive).

The system involves the installation of one or more cooling units outside the buildings, placed on the roof, on the wall, or at ground level, along with a specific air distribution system.

The system is completed by any extractors, gravity shutters, or controlled-opening windows useful for facilitating the expulsion of hot air.

For greater efficiency of adiabatic cooling systems, it is necessary to create conditions that facilitate the entry of fresh air and the simultaneous expulsion of hot air. In this regard, it is possible to exploit openings such as windows, doors, and large gates to improve overall performance and also favor the cooling of the roof, with a consequent reduction of the radiant component.

Sometimes it is necessary to use the system even during night hours, during which it is difficult if not impossible to keep the premises open. In these cases, it is advisable to install passive overpressure systems or specific devices for forced air extraction.

The coolers are designed to operate very simply. Starting from a basic system that only provides for the switching on and off of each individual cooler via ON/OFF switches, it is possible to achieve remote management of the entire system through a centralized interface and the relative wired network.

When your system is equipped with a centralized control system, your task is simply to configure the user interface: you can independently set parameters such as set-points and time slots for weekly programming. Furthermore, thanks to our network of Technical Assistance Centers, you have the possibility to further customize management: from the cleaning cycles of the evaporative panels to the timing of the tank water replacement, and other parameters that allow you to maximize efficiency and reduce consumption.

Yes! When we define the most suitable system solution for your needs together, we always take into account the centralized management methods of the system. If you already have a general or higher-order supervision system, we can seamlessly integrate the management of your adiabatic coolers as well.

Absolutely. The performance of adiabatic cooling systems depends largely on the thermo-hygrometric conditions of the external air, and in particular on its relative humidity rate. High humidity reduces the amount of heat that can be removed in the air-water exchange.

It is often thought that on summer days the relative humidity is always high, but this is not the case: as the air temperature increases, the relative humidity tends to decrease. Hourly data collected by the CTI (Italian Thermotechnical Committee) confirms this: during the hottest hours of summer days, humidity values generally remain low, guaranteeing favorable conditions for system operation.

On the rare days when humidity remains high even during the day, performance may be reduced and the temperature drop of the treated air may be limited to a few degrees. Despite this, the system continues to offer a perceptible benefit: even a lowering of 2–3°C leads to a clear improvement in comfort.

In the evening and at night, however, when the relative humidity increases, the system works in free-cooling mode: it directly utilizes the cooler external air without the need for further treatment and without water consumption.

In an industrial building, adiabatic cooling works by introducing large volumes of treated air into the environment, equal to approximately 10–15 air changes per hour. This guarantees a homogeneous and constant distribution of coolness. Naturally, considering the dynamics of air diffusion, temperatures very close to the supply temperatures are recorded in the areas directly hit by the flow, while in the surrounding areas the temperature is slightly higher, accompanied by a lower relative humidity level. This phenomenon is also due to the thermal loads present, such as operating machinery, lighting, and other internal heat sources.

To determine the correct temperature drop, it is important to take into account that it is influenced by the percentage of humidity present in the incoming air. The hotter and drier the day (therefore with a low percentage of humidity), the higher the performance of the cooling system will be. Conversely, as the humidity rate increases, efficiency will decrease.

Let's take a practical example: external air at 32°C with a humidity level of 45% can cool down by as much as 8-10°C, entering the work environment at a temperature of approximately 24°C.

During the system sizing phase, the hourly climatic data of the installation site are analyzed to define the average working conditions and estimate the expected performance of the cooling units. Simultaneously, the thermal load of the rooms to be treated is calculated, determined mainly by solar radiation (on roofs, walls, and glazed elements) and by the heat generated internally by the operating machines. Based on these evaluations, the number of units required is defined and the air distribution system is sized, also taking into account micro-localized conditions and relative tolerances.

During the winter season, when the internal temperature is higher than the external one, it can happen that the distribution ducts convey warm air towards the cooling units, resulting in heat loss. To avoid this, it is possible to apply a dedicated cover which, in addition to sealing the air passage, protects the unit from atmospheric agents.

If, on the other hand, the system must remain in operation even in winter to guarantee the minimum fresh air flow rate required by Legislative Decree 81/08, it will operate in ventilation-only mode. In this case, the water circuit is emptied to prevent the risk of water freezing.

To ensure correct and effective maintenance, the cooling units must undergo at least one cleaning per year. In the presence of water with high hardness, it is advisable to check the condition of the evaporative panels more frequently to prevent the formation of limescale and maintain the efficiency of the air-water exchange.

In general, it is good practice to schedule two interventions per year: one at the time of the first seasonal start-up to remove the protective cover, and one at the winter decommissioning to reposition it.

A further advantage of this system is that it does not use refrigerant fluids: consequently, it does not require any F-Gas certification from the maintenance technician.

The water tank empties automatically every 4 hours with a self-cleaning cycle to ensure the cleanliness of the evaporative panels and the cooling circuit. Furthermore, when the cooler turns off, an additional cleaning cycle is performed to prevent water stagnation. This repetitive process prevents the crystallization of minerals and ensures a long life and high efficiency of the cooling system.

To ensure the best performance of the air coolers, it is advisable to use potable water with a low mineral content to reduce limescale formation. Absolutely avoid the use of salt water or water with chemicals, as they could damage the internal components of the cooler. In case of high water hardness, the installation of a softener at the water inlet is recommended.

The anti-dust filters of the cooler can be cleaned with a rubber water hose, without detergents. This procedure is recommended before and after the summer season. During the summer, more frequent cleaning can be carried out with an air compressor.

For their operation, evaporative coolers exploit the natural principle of water evaporation. The latter acts as a natural refrigerant.

The individual units draw in hot air from the outside which, once filtered, passes through honeycomb panels soaked in water. The air, pushed by the fan, gives up part of its heat to the water contained in the evaporative packs, thus lowering its temperature.

The air is then introduced into the work environment at more comfortable temperatures.

The evaporative cooler can be installed on the roof or on the wall. Roof-mounted units are installed on the building's roof. Ideal for industrial, commercial, sports, railway environments, and livestock farms up to 6 meters in height, they offer uniform and efficient cooling without dispersion. Wall-mounted coolers are perfect for industrial and commercial environments with heights exceeding 6-8 meters. They allow for installation with air distribution at an optimal height without creating internal thermal discomfort, are versatile, and only require a window for the exhaust air outlet.

In the case of a large building with frequent door openings, the cooler uses only 4.85 kW of electrical energy. The water required for its operation is not wasted, as it evaporates during the cooling process and naturally returns to the environment through the hydrological cycle.

The frequency of replacement of the evaporative packs depends on multiple factors: the hardness of the water used for the evaporative process, the presence of external elements in the air being drawn in that could settle inside the panels, the hours of system use, and the maintenance performed. Usually, evaporative panels last from two to four years; if some time has passed, it is advisable to replace them even if they do not show obvious signs of dirt.

Evaporative cooling significantly improves air quality in work environments thanks to the continuous introduction of fresh replacement air. Unlike traditional systems, industrial coolers work best with doors and windows open, thus facilitating the expulsion of stale air and ensuring a fresh and clean environment throughout the day.