What is Evaporative Cooling?

People began toying around with the concept of evaporative cooling during the early 20th century, filing for US patents as early as 1906. Thermal comfort was, after all, a concern back in the day as well so that’s why people were just as interested in evaporative coolers as they are today. But what is evaporative cooling to begin with? It is the process by which air is cooled through evaporation. When it comes to air cooling though, most people will be familiar though instead with vapor compression refrigeration, or the process by which air-conditioning units cool air.

How Evaporative Coolers Work

An evaporative cooler essentially involves the use of a large fan that is fitted in front of water-moistened pads. These pads may be made out of different absorbent materials but they are typically made from wood shavings. The only criteria when it comes to materials for these pads is that they must be able to resist mildew and yet absorb a lot of moisture at the same time. The large fan works by drawing warm air from the outside and directing the air towards the pads. As the air passes through the pads, heat is absorbed and so cooled air is blown out. Temperatures may vary but the temperature at which the resulting cooled air is at is usually around 20 degrees F. Since the pads have to be perennially moistened, this is taken care of by a network of small pipes that distribute water. Since there will be water constantly making its way through the pads, not all the water will be absorbed by the air so whatever extra will pool at the bottom. Water that has been collected at the bottom though will be pumped back into the water reservoir for use in soaking the pads again. The water reservoir for evaporative cooling has an indicator level though to guide you when it’s time to refill it.

How is it different from vapor compression refrigeration?

Evaporative cooling employs a much simpler process of cooling compared to vapor compression refrigeration although the two both require evaporation in order to work. Their difference lies in that evaporation in vapor compression refrigeration happens within the system, with the resulting gas further processed by cooling and compression. After this, the gas returns to its liquid state where it is pushed into a space-cooling unit where cooled air passes. In evaporative coolers, evaporation happens outside the system when hot air passes through water-moistened pads. As the water evaporates from the air, heat is absorbed so cooling ensues. In terms of liquids being evaporated, evaporative coolers use water, while vapor compression refrigeration makes use of a refrigerant.

The benefits of using evaporative coolers

There are a number of reasons why evaporative cooling trumps vapor compression refrigeration. They are as follows:

Evaporative coolers blow in air continuously so there’s no chance at all for air to go stale, with air being actually being renewed every three minutes or so. This is highly ideal in promoting good health because you always breathe in fresh air. Because air is always being refreshed, meaning pollutants, smoke, and odors are constantly being driven out, this can be very good for those suffering from asthma and other respiratory conditions.
Since air around you doesn’t dry out as well, you also don’t have to deal with dry skin when you use evaporative coolers. Moisture is zapped from your skin alongside humidity in the air so it is normal for many people to suffer from dry, flaky skin when the weather is cold where humidity is low.
While evaporative cooling lets you breathe in fresh air continuously, evaporative coolers also let Mother Nature breathe easier because they emit less carbon dioxide than air-conditioning units. This way, you and Mother Nature both enjoy thermal comfort. Carbon dioxide is bad for the environment because it causes global warming.
In terms of costs, evaporative coolers cost about half of what it would take to install an air-conditioning system, while they also cost about only a quarter of what it would take to operate an air-conditioning system. In just one year, you could be looking at saving $150 in electrical costs when you use evaporative cooling.
Since there’s just the water pump and the fan motor working in evaporative coolers, they operate quite quietly compared to air-conditioning units. This is great not only for your home but for your neighbors as well because you both don’t have to contend with noise pollution. The fact that it has less components running is also the reason why evaporative coolers are cheaper to use.
Evaporative coolers are available either as portable models or fixed models like you would have set up in your home. This means that evaporative coolers are more flexible to use than air-conditioning units as you can use them for a wider range of needs.

Where evaporative cooling is best used

You can pretty much take advantage of evaporative coolers wherever you are but they work best in areas where the climate is hot and low on humidity. In the United States for instance, these would be the western parts of the country like Denver, Salt Lake City, Fresno, El Paso, Tucson, and Albuquerque. Conditions simulating hot and dry weather like what you would normally find in commercial kitchens, Laundromats, garages, dry cleaners, and poultry farms are also excellent venues for taking advantage of evaporative cooling.

Using the right evaporative coolers

Like any kind of equipment, evaporative coolers have certain capacities. It would make sense then that to take full advantage of evaporative coolers would mean to use them at the capacities they are capable of. Check ratings on evaporative coolers to guide you if you are using the right capacity. To compute for what you need, simply convert the measurement of the space you need to cool into cubic feet and then divide that number by two. This is the CFM (cubic feet per minute) capacity you need. The evaporative coolers you choose should at least carry the CFM rating you have computed to ensure optimum evaporative cooling is enjoyed.