How Misting Fans Work: The “Cool” Science Behind Misting Fans

Do you get tired of being forced to stay indoors during the hot summer days? Do you wish your children could break away from video screens and play outside? The need to stay near an air conditioner during summertime can make you feel like a prisoner in your own home, with all the windows and doors tightly closed.

Similarly, if you manage a warehouse or garage, your workers may run the risk of heat exhaustion or heat stroke simply by doing their jobs during summer weather. Many industrial environments involve hazardous high temperatures, making it difficult for workers to concentrate. The United Steel Workers has published guidelines for employers, pointing out the health and safety hazards of excessively hot workplaces.

Mist Fans Offer New Freedom

Whether you’re at home or at work, misting fans let you move around freely and focus on what you’re doing. Using three different thermodynamic methods of cooling, these versatile tools provide outdoor comfort in the hottest weather. Now you can throw open your doors and invite friends over for pool parties and backyard barbecues. Everyone will enjoy the cooler air created by your patio misting, and they’ll want to linger on into the evening.

In commercial and industrial settings, a few portable misting fans can make an enormous difference in the morale and health of your workers. Increased humidity also results in less static electricity, while the tiny water droplets reduce particulate matter in the air. The fine mist from just one fan will lower the temperature by as much as 30 degrees F in areas up to 1,000 square feet. Outdoor festivals, sporting events and other summertime gatherings can offer cool comfort anywhere that has a 120-volt electrical outlet. Plugs and cords on portable misting fans are waterproof for safe operation, and the fans themselves are made from stainless steel and other outdoor-compatible materials.

How Misting Fans Work

Mist systems come in various configurations, but portable fans offer the greatest versatility. These appliances combine a powerful blower fan with a high-pressure water pump. The water is blown through misting nozzles or a centrifugal misting system, producing a fog of water droplets so fine they can barely be seen. This fog is so fine that your skin and clothing won’t feel wet; instead, you’ll simply experience a fresh coolness. You need a water source for your misting fan. The NewAir fans have a connector for your garden hose, while the Luma Comfort models include a built-in water tank that you fill ahead of time. These closed water tanks allow your fan to be used indoors with no risk of leakage. When you use this type of misting fan indoors, you are not activating the water function — it just becomes a regular electric fan like any other.

Every Feature Is Adjustable

Misting fans are made with flexibility in mind. They include easy adjustments for height, speed, tilt, oscillation, amount of mist and more, so that you can match the cooling function to your precise needs. The fans come in sizes to provide outdoor cooling for areas from 500 to 1,000 square feet.

More Energy-Efficient Than Air Conditioners

While misting systems are used in outdoor settings where air conditioners aren’t appropriate, it’s still interesting to note the comparative energy efficiency of the two methods of cooling. A very compact portable air conditioner uses over 900 watts of power, while the largest misting fan we offer consumes less than 300 watts. Furthermore, one gallon of water has the cooling power of 7,776 BTUs per hour. This efficiency keeps your electric bills low, while you enjoy the luxury of cooling the outdoors without any worry about wasting energy.

How Misting Fans Work to Keep You Cool

The science of thermodynamics identifies three ways in which your body can lose heat, or cool off: conduction, evaporation and convection. Misting fans make use of all of three methods.

  • • Convection is the removal of heat from a surface by currents of air or water. When you stand in a breeze, the cool air flowing along your skin carries off some of your body heat. All fans work by convection, and they are helpful as long as the air is cooler than about 98 degrees (your body temperature). If a fan blows dry air warmer than 98 degrees onto dry skin, however, convection will work in the opposite direction and the breeze will actually heat you up. This is why wind in very hot desert environments adds to the heat hazard.

The presence of fine water droplets right on your skin adds two additional cooling mechanisms to the convection action of an ordinary fan, and allows misting fans to provide comfort in temperatures over 98 degrees. Here’s how:

  • • Conduction is the direct temperature transfer that happens when you’re in contact with something (like water) that’s a good conductor. When you use a misting fan, each tiny drop of water is cooler than your body temperature, and it will transfer its coolness to the area of your skin that it touches. The water droplets will be cool even on very hot days because they begin to evaporate as they move through the air, and this cools them off before they reach your skin. Water conducts temperature 25 times more effectively than air, so it cools your skin much faster. Here’s an example of water’s excellent conductivity: If you walk outside when it’s 70 degrees, the air will feel quite comfortable even though it’s almost 30 degrees lower than your body temperature. You may be fine in short sleeves. However, if you jump into a 70 degree pool, it will certainly be a cold plunge, and surfers in 70-degree water often wear wetsuits to keep from getting chilled.
  • • Evaporation is the wondrously simple physical reaction that is at the heart of misting fans’ effectiveness. It cools the air as well as your body. Have you ever wondered exactly what happens when water evaporates or why it’s so effective at cooling things off? When water evaporates, what’s happening is that individual H2O molecules are breaking free of the connected mass of liquid and drifting off into the air. In order for the molecules to perform this break-away trick, they need quite a lot of heat energy, and they take that heat from whatever is nearest. (One cube of water that’s less than half an inch on a side requires more than 600 calories of heat energy to vaporize.) When there is moisture on your skin, those molecules will use some of your body heat to transform themselves into water vapor. As they remove that heat from your skin, it gives you a sensation of coolness.

Portable misting systems cool the air through evaporation in the same way. As the fine mist shoots out from the fan, some of it simply disappears. The mist that disappears has evaporated. Since this transformation requires heat, the molecules pull the heat they need from the air around them, leaving the air cooler. Furthermore, the smaller the water drop, the faster it will evaporate, because more of its molecules are on the surface. The ultra-fine fog produced by a misting fan evaporates rapidly, maximizing the effectiveness of the process.

Moving Air Speeds Up Evaporation

If your skin is moist, it feels cool. However, if you stand in the breeze from a fan, that coolness noticeably increases. This is because in motionless air, the water molecules tend to hang around right above the place they evaporated from. This makes the air next to your skin more humid, so there’s less room for any more vapor. Wind blows away the vaporized water molecules, leaving the air near your skin drier, so there’s more room for new molecules to turn into vapor and float away.

Do You Live in a Good Region for a Misting Fan?

Evaporative cooling is most effective in less humid environments, such as the western part of the United States. If you live in a city like Phoenix, you know how dry the air feels on a summer day. If water spills, it evaporates almost instantly, because the hot, dry air can hold so much water. The drier and hotter your air, the more efficiently you can cool off by harnessing the power of evaporation. If you live in the east, however, your summer days typically have high humidity. An air conditioning unit will give you greater comfort than a misting fan will, because everything feels damp already.

Relative Humidity Changes Throughout the Day

If the early morning weather report predicts a hot summer day and the relative humidity is already somewhat high, you may figure that the air will be too moist to use your misting fan. However, relative humidity is a way of saying how much of the air’s capacity to hold moisture is already filled up. Warmer air has a larger capacity for holding water vapor, so its relative humidity (or filled-up-ness) is lower. By mid afternoon, when it’s much warmer than it was in the morning, the air has more room for new water vapor and your misting fan will be able cool you more efficiently.

Make Your Summer Environment Healthier

Mist is so effective at cleaning smog and contaminants from the air we breathe that China actually deploys “mist cannons” in its most polluted cities as a way of eliminating particulates and smog! You and your employees, friends and family members will all benefit from the improved air quality and cool comfort that a portable misting system offers.

 


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NewAir Portable Misting Fans

  • • Refreshing mist significantly decreases outdoor temperature
  • • Three fan speeds cool up to 600 sq. ft. of patio space
  • • Compatible with any standard garden hose

 

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The post How Misting Fans Work: The “Cool” Science Behind Misting Fans appeared first on NewAir.com Knowledge Base.

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