The Evaporative Air Cooler is combine with a fan blower and water tank, compare with the normal cooling fan, it can make extra cooling by using the water to take away the hot when the hot air coming into the machine, as you can see the picture as below,:

The pump will pump up the cold water from the tank, and the cold water go through the cooling pads ( honeycomb filter),so the hot air temperature will be absorbed by the cold water, then the cool air will blow out by the fan blower, it is quite smart method to cool down the room temperature, compare with Portable air conditioner, it is much cheaper for electric bills, and no need to do any installation, the only way is just filling the tank by cold water and put the ice into it regularly, the air cooler is a good partner to trust in the summer time.