Things You May Not Know About Evaporative Cooling

March 17 2017

James Patten


Evaporative cooling has been a popular method of air conditioning for centuries. The earliest example of this evaporative cooling can be found in Ancient Egypt, where they used reeds soaked in water hanged throughout the house to cool the air inside when wind blew through the windows.

Now it is one of the most popular forms of cooling around the world, but you may not know everything about it. Here are some things you may not know about evaporative cooling.

Physical Processes

Evaporative cooling features a process known as the adiabatic process; this occurs when the energy needed to evaporate the water is taken from the air and is then converted into latent heat. An adiabatic process is one where there is no transfer of heat or matter between a system and its surroundings. This means that there is a temperature drop without changing the amount of heat in the room.

Humidity Can Change Everything

Humidity represents the amount of water vapour present in the air. However, humidity can greatly alter the effectiveness of evaporative cooling. For example, if the humidity is at its maximum (i.e. 100%) then the dew point is equal to the current temperature of the room. With this in mind, it means that clouds can actually form at ground level due to the amount of water vapour present.

View of white clouds in blue sky and lands under clouds

This doesn’t happen regularly, but the main issue is that if the humidity is very high, the rate of evaporation decreases. The result of which isn’t effective for evaporative cooling systems. Therefore, it is more likely to find evaporative cooling systems in hot countries as opposed to humid ones.

Evaporation is a Sensitive Process

The following factors can greatly influence the rate of evaporation:

  • Pressure
  • Temperature
  • Intermolecular forces
  • Rate of flow of air
  • Concentration of substances in the air – i.e. humidity

Because of these factors, it is important to make sure that the right conditions are met so that the evaporative cooling process is as efficient as possible.

If the pressure is too high, then the evaporation rate decreases because there is a greater exertion acting on the material where the evaporation must take place. If the rate of flow of air is consistent, then evaporation will also be consistent, but it greatly depends on the concentration of particles in the air.

If the air is dry, this will encourage faster evaporation, and if the air is more humid than previously anticipated, this will greatly affect the evaporative cooling process.

Building with an evaporative cooling system

Understanding the importance of each aspect of evaporative cooling means that, if you are thinking of implementing an evaporative cooling system in your warehouse or office space, you know the benefits and limitations of the evaporation process.

At Heritage Heating and Cooling, we are able to supply the highest quality evaporative cooling systems for your warehouse, office, or any other business-related establishment.

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