They add moisture and air flow for the most part the evaporative coolers, swamp coolers, and waterwalls do. Of course you have to create enough and have enough air flow for the exchange of fresh air by pulling in the hot air from outside and exhausting it out the other side. Air in air out. The hot air being pulled across the wet pads is cooled.
Air Conditioned air can use fresh air via a vent but usually uses recirculated air from within the room. They use mechanical means to create cooling. Thats why conditioned air is drier bec its all over the coil in the form of water and why window units drip. That water is pure water too and good for your plants by the way.
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. Your rooms humidity gets transferred by the displacement of the heat being blown across a cold coil in the unit. An AC rooms pressure is usually positive and you dont get as much fresh air exchanges. And there's that word Entropy again.
Entropy has been reached when there is no more work to be done
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