A Refresher Course: What is Evaporative Cooling?

Posted by Melodie Elliott on Thu, May 26, 2016 @ 03:55 PM

Ah, the sultry days of summer are just around the corner. Depending on where you live, the mercury may already be rising. It is helpful to know your cooling options. Today, many people are familiar with traditional cooling methods ranging from air-conditioning (AC) to fans. AC works in closed spaces where the recirculated cool air can be maximized with use of refrigerant and a compressor. Fans – both oscillating and ceiling options - generate air but it is not chilled in any capacity.   

What about evaporative cooling? What is it exactly? Evaporative cooling is, quite simply, cooling with water.  A few relatable examples of evaporative cooling at work is the cooling sensation felt when climbing out of a swimming pool, perspiration as a form of natural cooling to the body or feeling the cool breeze blowing across a lake. By evaporating water, the temperature of the air in contact with the liquid water will lower as an endothermic reaction takes place.  During this reaction, the liquid water changes to a gas and the temperature of the air lowers. 

A portable evaporative cooler essentially works off this principle by acting as a cooling fan that uses water, a pump and a wetted surface to create the naturally occurring process of evaporation to cool warm air and drop temperatures.  By pulling air across water, the temperature of the air will lower.  A control system within the evaporative cooler operates the pump to assist in creating this effect and the fan distributes the cool air.



One unique aspect of the evaporative cooler is that it actually works best with a supply of outside ambient air to deliver a temperature reduction and cooling effects.  While evaporative coolers achieve significant temperature drops in more arid climates and drier spaces, they provide relief from the heat in any climate.  For example, in regions where relative humidity reaches 70% at midday with temperatures over 90 degrees Fahrenheit, evaporative coolers have been shown to offer noteworthy relief. Given that relative humidity is lowest in the afternoon when the temperature is at its highest, an effective evaporative cooling scenario is achievable.

Example: Evaporative coolers have been proven to deliver a temperature reduction from 8 to 10 degrees in the morning in the highest humidity regions (Miami, New Orleans, or Boston), and  up to 12 to 15 degrees later in the day when the  relative humidity goes down as the temperature goes up.

The technology at the center of an evaporative cooling system is the evaporative media (e.g. the surface) that collects water. Air passes through the media and is cooled as the water evaporates. The evaporative media is specially treated to prevent deterioration and ensure a long service life.  A special water distribution system spreads water over the surface of the media within the cooling unit to ensure a uniform water supply.  This keeps the entire air to contact surface thoroughly wet. A control system operates the water pump and distributes the cool air.  What difference does this evaporative media make? We’ll take a deeper look at that in next week’s post. Stay tuned.


Topics: evaporative cooling, evaporative cooler vs air conditioner, air cooler, evaporative cooling media

Subscribe to Email Updates

Recent Posts

Posts by Topic

see all