Updated: Oct 3, 2019
Evaporative cooling is the oldest, safest, greenest, and most efficient way to cool. We say that a lot but how exactly does evaporative cooling work?
I remember when I was a kid and I used to gather with my friends on a hot summer day to run through the sprinklers. Then the wind would kick up and very quickly we would go from dying of heat to freezing cold.
That is the concept of evaporative cooling. You take water and wind and you get cooling. In ancient days they would put wet cloths over open windows and doors and let the wind blow through to provide cooling on hot days.
The technology has advanced since then but the ideas and the ingredients stay the same. Today we use evaporative cooling systems such as coolers, pre-coolers, swamp coolers, wet decks, etc. to bring us the same cool result. An efficient and green way to to keep cool.
It is simple the hot air moves through the water soaked filter and BAM! Out comes cool air!
Evaporative cooling uses the principle of water evaporation to cool, no environmentally dangerous refrigerants, just cool clean water. Just like that cool feeling felt when running through the sprinklers.
So, now we know how it works overall. Now let us talk a little about the equipment aspect. We have come a long way from hanging wet cloths over open doors. Now we can use different equipment for evaporative cooling to create the wind and water. The wet cloth is now replaced by a special engineered filter or evaporative cooling media.
Water applied to this extensive, corrugated media surface and mixes with air which passes through the media. Energy is required to change the liquid water into a vapor, this process called "Evaporation" absorbs heat from the air stream which decreases the air temperature while increasing the relative humidity.
The media is wetted from either a drip‐type or spray‐type water distribution system to saturate the media. The media is corrugated to maximize the contact area between the air and water.
The hot air is passed through the media and is cooled as it evaporates the water into the air stream. In this process, called direct evaporative cooling, the air’s temperature is lowered but the moisture content is increased. In a typical application in Phoenix, AZ summer design conditions are 108°F with 70°F wet bulb temperature, 16% relative humidity and 48 grains of moisture per pound of dry air.
As the air is passed through traditional portable evaporative coolers the air is cooled to 78°F with 70°F wet bulb temperature, 68% relative humidity, and 96 grains of moisture. Obviously, the temperature is significantly cooler and the humidity level is much higher. All of this cooling is achieved with relatively low energy consumption since the cooling uses only a water pump and a little more horsepower for air movement. Typically, an evaporative cooling system will utilize approximately 80% less energy than a mechanical refrigeration system.
In many areas, the increased humidity levels are a welcome advantage of evaporative cooling as a source of humidification during both summer and winter seasons.
However, in many regions and applications higher ambient humidity levels make direct evaporative cooling less effective and comfortable. Indirect evaporative cooling, a relatively new concept, utilizes the same process of direct evaporative cooling to cool a secondary independent air stream which cools some sort of medium. This medium then cools the primary independent air stream with no moisture addition to that primary air stream. Common processes include utilization of cross flow plate exchangers, heat pipes, and a system involving a cooling tower and a cool water coil.
Here at ATEC/Indirex we specialize in all things evaporative cooling, from the equipment used to the safest evaporative cooling media in the world. Our team is constantly working on improving the world of cooling through new ideas and technologies. We have spent over 20 years as a master distributor of media and are proud of this earth friendly way to cool.
Thanks for reading, here are a few more tidbits about evaporative cooling;
Evaporative cooling has many factors, which are driving interest in this technology. Among these are:
* Environmentally friendly Evaporative Cooling versus environmental concerns of refrigerants used in mechanical refrigeration.
* Improved indoor air quality through the air washing nature of evaporative cooling.
* Low energy usage versus mechanical refrigeration enhances your energy management and saves money.
* Low operational costs makes evaporative cooling a great alternative to traditional ventilation-only systems.
* Transportable Evaporative Cooling can reduce overall cooling requirements on systems which are struggling with capacity due to increased outdoor air or internal load requirements.
Thank you and have a cool day!