Evaporation is the process of liquid turning to gas. It takes heat energy to produce evaporation, like the heat energy of a gas flame when you boil away the water in a saucepan. Don’t leave the house when you do!
If you force the evaporation by another method, the heat “debt” still has to be paid. It’s extracted from the surrounding area.
Methods of forcing evaporation than by direct heat include:
- Pressure reduction, used in the refrigeration cycle,
- Moving air over a liquid surface.
Evaporative coolers use the second principle, drawing air over damp pads to cool a building.
While air conditioners work in sealed indoor environments and repeatedly re-circulate the same air, evaporative coolers work in non-sealed environments. Instead of recirculating the same air, they continually pull in fresh outside air.
Parts of a Swamp Cooler
An evaporative cooler has four main components:
- A water tank
- A pump
- Cooling pads
- A ventilator motor attached to a fan
The pump saturates the cooling pads with water. The fan draws outdoor air over the saturated cooling pads, triggering evaporation and reducing temperatures in the building.
More sophisticated coolers come equipped with a filter to block dust and other particles.
Sometimes, evaporative coolers are attached to ductwork like a central air conditioner. But most coolers circulate air directly into a room.