What is evaporative cooling and why is it good?

Evaporative cooling is the use of evaporated water to cool hot air. It is what happens when you get out of a swimming pool on hot day. The wind hitting your wet body feels chill until you dry. This is because of the evaporating water.

Evaporative cooling in history

The ancient Greeks, Romans and Egyptians used evaporative cooling by simply hanging wet mats in front of window and tent openings. The hot air blowing through the mats then helped keep inside air at a reasonable temperature. These mats were an early version of our modern-day cooling pads.

The invention of the first mechanical ventilation fans in the 15th century and later on entire evaporative cooling systems combining cooling towers and fans for British textile manufacturers in the 18th century, laid the keel of the evaporative cooling systems we know and use today.

How modern evaporative cooling systems work

The heart of the modern evaporative cooling system is the cooling pad where water evaporates and air passing through is then cooled. The cooling pads are manufactured from fluted cellulose sheets that are glued together. The material is impregnated with special compounds to prevent rot and ensure a long service life and minimal maintenance.

A special water distribution system spreads water over the cooling pads, ensuring a uniform supply of water that keeps the entire surface wet to maximize cooling capability. Fans create a negative pressure, causing air to be drawn through the pads. Evaporation results from contact between air and water. A control system operates the water pump and the fan distributes the cool air in the area.

The benefits of evaporative cooling:

• Clean air that reduces the risk of bacteria and virus
• No chemicals or refrigerants
• Low energy consumption
• Virtually maintenance-free equipment

Evaporative cooling and bacteria and virus

Our evaporative cooling solutions all deliver a very clean air quality because they come with air pre-filtering. Combined with the slight humidity resulting from using evaporative cooling, this removes bacteria and slows down the spread of viruses in the air.

Evaporative cooling and humidity

A given volume of air at a certain temperature and pressure can absorb and hold a certain amount of water vapor. If that volume of air contains 65% of its moisture capacity, it is said to be at 65% relative humidity.

The hotter the day, the drier the air, the more cooling can be done by means of evaporation. In other words, the cooling effect is best when you need it most.

Our evaporative coolers are developed to work well in high-humidity environments too, however, and will remain much more efficient than a simple fan that just circulates warm air. Our coolers will increase humidity by 2 to 5%, depending on temperature and humidity in the environment you want to cool. The slight increase is not noticeable in ventilated areas where the air produced by the unit is exhausted.

Cooling capability

The below table illustrates the theoretical outgoing air temperature of an evaporative cooler at a given relative humidity and incoming air temperature. As illustrated, an incoming air temperature of 35°C at 30% relative humidity makes it possible for the evaporative cooler to generate an outgoing air temperature of 26°C.