An adiabatic cooling system takes advantage of the difference between the dry bulb temperature and the wet bulb temperature of the air. This difference can vary in practice between 0 and 9 °C, depending on the relative humidity of the air and the atmospheric pressure. Consequently, the greater this difference, the more feasible the effective use of adiabatic cooling in industrial and commercial air conditioning systems.
How is adiabatic cooling done?
Normally, the air has an affinity for water. Therefore, the drier the air, the more moisture it can absorb. In this way, air at 30 °C, with 60% relative humidity, can lose up to 4.5 °C if it is saturated with water up to 85%. However, when the air already has 85% relative humidity, it can only absorb water up to 95%. In such a case, you will hardly be able to lose 1.5°C or so.
To add moisture to the air, it is passed through moistened cellulose panels. In addition, water can also be sprayed directly into the air stream. This is how an adiabatic cooler works to lower the temperature of the air.
What is the adiabatic cooling system made of?
The adiabatic cooling system is composed of a box or closed metal structure. Inside the box, an electric fan forces air through moistened cellulose panels, then blows it where it’s needed. In this sense, the cooled air can go directly to a living space or to a heat exchanger coil.
In the lower part of the adiabatic cooler, there is a water tank, which is driven by a pump toward atomizing nozzles. These nozzles keep the cellulose panels moist.
On the other hand, frequency inverter equipment is responsible for controlling the speed of the fan, to regulate the airflow. The latter is very important because the air should not pass through the panels so quickly, in order to absorb as much water as possible.
Differences between evaporative cooling and an adiabatic refrigerator
It is common to confuse an adiabatic cooling system with another by evaporation. However, these have very different working principles. That is, in evaporative cooling, water is sprayed directly onto the object to be cooled. Consequently, the water changes from liquid to vapor phase on said object, which accelerates the absorption of heat in it. Finally, forced air from a fan removes said vapor, completing the cooling.
However, in adiabatic cooling, the air is cooled first, due to the increase in relative humidity in the air. The cooled air is then forced against the coil into the living room or other room to be cooled.
When is it convenient to use an adiabatic cooling system?
Normally, an adiabatic cooling system is used in places with an ambient temperature equal to or greater than 30 °C. However, the relative humidity of the air must be considered, if it is greater than 75%, it is not feasible to use this cooling system. On the other hand, when the humidity is below 65%, this cooling system is possible.
It should be noted that adiabatic cooling does not replace or compete with evaporative cooling, but rather is a complementary system. On the other hand, in industrial air conditioning above 1 MW, evaporative cooling systems cannot be replaced by merely adiabatic equipment.
It is common in industrial refrigeration to find mixed cooling systems. That is equipment where the air receives a previous adiabatic cooling, before passing to the evaporative cooling section. These teams reach high levels of efficiency, although they have a significantly higher price.
Advantages of an adiabatic cooling system
When compared to a conventional cooling tower or evaporative system, the adiabatic cooling system has very low water consumption. This is particularly important in areas with scarce water resources. In addition, this system requires less maintenance than any other system that uses water.
On the other hand, an adiabatic refrigerator consumes little energy, which is important in industrial air conditioning to increase energy efficiency. In addition, these equipment are designed to work only in ventilation mode, during night hours. Therefore, this helps to further reduce water consumption, also reducing equipment maintenance.
Adiabatic cooling systems have helped to extend the use of CO2 refrigeration in geographical areas with hot climates. Normally, in warm areas, CO2 works in a transcritical way, since the critical temperature of CO2 is relatively low (32 °C). However, with the reduction in air temperature due to the adiabatic effect, it is possible to make CO2 work subcritical, in warm regions.
Do you need an adiabatic air cooler for your industrial refrigeration or air conditioning system?
If you want to take advantage of the benefits of an adiabatic cooling system, at Intersam we offer you all our experience in the design and construction of adiabatic air coolers. We guarantee long-lasting equipment tailored to your needs, thanks to the fact that we use the highest quality materials. Therefore, in case of doubt, you can contact us whenever you want, since we are specialists in industrial refrigeration and we have more than 25 years of experience.