When we talk about air conditioners we generally talk in terms of a device which is going to cool the surrounding air and provide us comfort. Some may also think dehumidifying as an additional function of the device. Although this may be true for a great extent of air conditioners, it must be remembered that dehumidifying is not always the best option. For example, in the dry climates of Arizona having an air conditioner which also dehumidifies to an extent would be foolish. Good news is all air conditioners are not dehumidifiers and some function in the exactly opposite manner. They actually increase the humidity of the air inside the room. They are also popularly known as 'evaporative' or 'swamp' coolers.

These are meant to provide comfort in places where the climate is not only hot but dry too. These devices actually suck in air from the outside through a wet pad. This ensures that the sensible heat of the air is reduced. However, it must be remembered that the total heat content of the air that has been sucked in remains unchanged as the sum of the sensible and latent heat remains constant. The sensible heat of the air that is reduced is actually converted to latent heat as the water from the wet cooler pads is evaporated absorbing heat from the air. The drier the air that enters the device, the better are the results. the good thing about these devices is that they are relatively cheaper than the regular air conditioners and the maintenance is also hassle free.

We also have the devices which are based on the technology of absorptive refrigeration. What this process basically does is to absorb heat to produce cooling. There are three stages to the entire process. First of all, the air is dehumidified by the cooler. This is done by a spray of salt-water or brine. It is through osmosis that the brine absorbs water vapor from the air. During the second stage water is sprayed in the air. This cools the air because of the evaporation that follows. To conclude, the air passes again through another brine spray so that the humidity of the air is controlled. Distillation ensures that the brine remains concentrated. This system has been used in some hospitals.

Such Evaporative air conditioners are separate from what we come across regularly and can actually provide a solution to those staying in hot, dry climates.