Prove me wrong, please?
edit: thanks for all the great comments, this is really helpful. My main take-away is that it does work, but requires dry air. In humid conditions it doesn’t really do anything.
Spouse bought this thing that claims to cool the air by blowing across some moist pads. It’s about as large as a toaster, and it has a small water tank on the side. The water drips onto the bottom of the device, where it is soaked up by a sort of filter. A fan blows air through the filter.
- Spouse insists that the AIR gets cooled by evaporation.
- I say the FILTER gets cooled by evaporation.
- Spouse says the cooled filter then cools the air, so it works.
- I say the evaporation pulls heat (and water) from the filter, so the output is actually air that is both warmer and wetter than the input air. That’s not A/C, that’s a sauna. (Let’s ignore the microscopic amount of heat generated by the cheap Chinese fan.)
By my reckoning, the only way to cool a ROOM is to transport the heat outside. This does not do that.
We can cool OURSELVES by letting a regular fan blow on us = WE are the moist filter, and the evaporation of our sweat cools us. One could argue that the slightly more humid air from this device has a better heat transfer capacity than drier air, but still, it is easier to sweat away heat in dry air than in humid air.
Am I crazy? I welcome your judgment!
https://en.wikipedia.org/wiki/Evaporative_cooler
You do do the same thing.
However, I have a small evaporative cooler which can evaporate 5 gallons of water a day. You aren’t gonna do that yourself, and it’d drench you in sweat.
They’re a couple of times more energy-efficient than air conditioners, though more maintenance heavy and require being in a dry climate. They also (normally) require outside air coming in, which is nice in that it keeps carbon dioxide levels down but means pollen or whatever too unless you filter that.
If you’re using an evaporative cooler correctly, you have to keep (dry) outside air coming in so that it doesn’t just act like a giant humidifier.
FWIW, you can actually use what’s called an “indirect” evaporative cooler. That has outside air come in, go through an evaporative cooler to cool it, then sends that through a heat exchangerthat dumps heat from inside air into the heat exchanger, then sends the moist air outside without increasing inside humidity.
You can even extend that to use the cooled, humid air as the input to the “outside” side of an air conditioner’s heat exchanger that dumps best to the outdoors. That is basically an indirect evaporative cooler plus a heat pump, a “hybrid” air conditioner, which will boost the air conditioner’s efficiency.
Unfortunately, I don’t see much by way of small indirect evaporative coolers or small “hybrid” air conditioners on the market, though it’s not technically-complicated to build one. Seems to be done by large commercial installations.