I live in a high humidity (75%) climate.
I wanted to know what happens when you combine a light humidifier with a normal AC set on "dry" mode.
The AC is activity reducing humidity, which helps me "feel" cool since water evaporates better off your body.
However, I wonder if I can reduce my energy bill by running evaporative cooling using "cold" new water ( not the water collected by the AC ).
In dries climate you use swamp cooler to reduce the temperature.
The idea here is ( if laws of thermo is obeyed ) is the water leaving the air con unit has some residual heat.
As the air gets dries it gets less efficient for the AC to reduce the temperature.
Each watt of energy gets rid of fewer BTU as the air gets drier.
It's important to note that as you add normal water mist to your room, it evaporates and absorbs heat itself.
As this vapor moves to the AC, you need very little energy ( dew point ) to turn it back to water.
The water contains extra heat that gets removed through the drain pipe.
Without this extra mist humidity, the AC would pump the heat through its internal refrigerant.
The idea here is not to replace a normal AC – a swamp cooler doesn't help in 80% humidity.
The idea here it to enhance the efficiency of a normal AC, even if it helps by 5% thats huge energy saving.
Best Answer
One does not simply ignore thermodynamics ;)
Latent heat of evaporation works both ways. You need to provide 683 Wh (Watt*hours) of energy to turn 1 kg of water into water vapour... and if you have one kg of water vapour, you need to suck the same amount of energy out of it to turn it back into liquid water. You can view condensation as "pumping heat out of water vapor", or "whater vapor heats whatever it condenses on" but the way to visualize it does not change the physical phenomenon, which involves an amount of energy (heat) corresponding to the latent heat of evaporation.
If you use a mister to evaporate water, it will take the energy from the room, but it will return this energy to the AC unit as the AC unit condenses it back to liquid. From the point of view of the AC unit the only difference would be, maybe, a little bit better heat transfer on the evaporator fins.
So it shouldn't do anything to the electricity bill, but it will make the room moister and less comfortable.