Eli5 how does a dehumidifier suck water out of the air?
In: Technology
Depends what kind there are a few varieties
One uses the hot air on to cold surface
I think the second is silica based and uses gravity
It sucks air into an area with a cold surface, which causes the moisture in the air to condense onto it (like your mirror after a shower), before dripping down into the collection pot.
Air’s ability to hold evaporated water decreases as it gets colder.
When reducing the temperature of air, there comes a point where air as at maximum water capacity. When it’s like this, it is said to be “saturated”. Make the air colder than this and it will be “supersaturated”. Supersaturated air will begin to deposit liquid water on cool surfaces, as the air can no longer hold it.
A dehumidifier works by cooling down a piece of itself and blowing air across it. This cools down the air to the point of supersaturation and forces water to condense on the cold part. It drips down into a collection pan or gets pumped out, depending on your device.
FYI, the temperature where air becomes saturated is what the “dew point” is, if you’ve ever seen that on a weather forecast. It’s the temperature where, if the air gets any colder, water will condense onto random objects, such as blades of grass. That’s where dew comes from. Dew tends to appear in the morning because the air cools down over night, bringing the air temperature below its dew point and causing water to deposit everywhere. You could think of a dehumidifier as a “dew-making machine”, I guess, since it does the same thing.
Also FYI, a dehumidifier is essentially the same exact machine as an air conditioner. An air conditioner works by making a piece of itself cold and blowing air across it as well. The only real difference is that an air conditioner takes the heat it sucked out of the cold part and pumps it into a hot part, which is placed outside of the space you’re trying to cool down. Any water it collects is simply dumped into a pan and left to evaporate back into the air, or it’s slowly bled out through a drain. A dehumidifier doesn’t care about pumping heat out of a space, so it just pumps the heat straight back into the room it stole the heat from and tosses out the water instead.
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