evaporation cooling

Evaporative cooling – physical phenomenon as air cooling solution

Have you ever noticed how perspiration or sweat cool our body? It’s a natural occurrence of cooling through evaporation. As perspiration evaporates it absorbs heat to cool our skin. Evaporative cooling is based on this principle and is well suited for climates where the air is hot and humidity is low. They combine the natural cooling properties of water with a steady breeze to lower indoor temperatures.  

What is evaporative cooling?

Evaporative cooling is a physical phenomenon in which evaporation of a liquid, typically into surrounding air, cools an object or a liquid in contact with it. Latent heat describes the amount of heat that is needed to evaporate the liquid; this heat comes from the liquid itself and the surrounding gas and surfaces. 

How does evaporative coolers work

evaporative cooling

When considering water evaporating into air, the wet-bulb temperature, as compared to the air’s dry-bulb temperature, is a measure of the potential for cooling. The greater the difference between the two temperatures, the greater the effect. When the temperatures are the same, no net evaporation of water in air occurs, thus there is no cooling effect. An evaporative cooler produces effective cooling by combining a natural process – water evaporation – with a simple, reliable air-moving system. Fresh outside air is pulled through moist pads where it is cooled by evaporation and circulated through a house or building by a large blower. As this happens, the temperature of the outside air can be lowered as much as 30 degrees.

Evaporative cooling is quite energy-efficient and most effective in areas of low humidity and hot temperatures.

Applications

So, how we can use evaporative cooling? This technology is especially well suited for climates where the air is hot and humidity is low. In the United States, the western/mountain states are good locations, with evaporative coolers prevalent in cities like Denver, Salt Lake City, Albuquerque, El Paso, Tucson and Fresno. Evaporative air conditioning is also popular and well-suited to the southern (temperate) part of Australia. In dry, arid climates, the installation and operating cost of an evaporative cooler can be much lower than that of refrigerative air conditioning, often by 80% or so. However, evaporative cooling and vapor-compression air conditioning are sometimes used in combination to yield optimal cooling results. Some evaporative coolers may also serve as humidifiers in the heating season.

Evaporative cooling vs air conditioning

Evaporative coolers can be used as the sole cooling system, or to complement existing air conditioning systems. However, they should never be used at the same time, as one adds humidity while the other removes it. Evaporative coolers offer several benefits over air conditioning, including:

  • Low installation and maintenance costs
  • 75% less electricity usage
  • Powered by a standard 120 volt outlet
  • No ozone damaging refrigerants
  • Fresh air flow pushes out warm air, smoke and pollution
  • Breeze makes effective room temperature feel 4 to 6 degrees cooler

If you are in the process of choosing among avaporative cooling and air conditioning, feel free to ask any additional questions below.  Or join my private Facebook group here, and ask the entire community about finding a right answer.

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