In hot places, it becomes necessary to cool the inside of buildings. Modern buildings have refrigeration systems, commonly کولر گازی گری referred to as air cooling or AC for short. An alternate system of cooling is a swamp cooler. Although it sounds primitive, a swamp cooler can be effective, and is almost always much cooler to run than an air conditioning unit.
Swamp refridgerators were developed, not in swampy areas, but in the desert. Trent Goettl, in the early the twentieth century, improved home cooling in the southwestern desert of Arizona. Although the company would later move to become a major Phoenix air cooling supplier, they started with swamp refridgerators. These worked well in the hot, dry air in ways that they would never have worked in the Midwest or Deep South.
Swamp refridgerators work by the principle of evaporation. When water evaporates it uses heat energy to change state from liquid to gas. Much like boiling water requires heat, evaporating require heat. This heat is drawn from the surrounding air. A swamp cooler is a large box with sponge-like pads lining three sides and the top. A large fan forms the fourth side. A floor of the cooler is a catch container for water, which is introduced at the top of the pads. Water runs down the walls, keeping the pads saturated. Air flows through the walls of the cooler, through the wet pads, and out through the fan, into the room. On a dry day, the water in the pads evaporates quickly, keeping the pads and air quite cold. On a humid day, the water in the pads does not evaporate well, and the result is that the cooler only brings down the temperature slightly, while humidifying the room.
Air cooling works on a totally different scientific principle, that of Boyle’s gas law. Increasing the pressure of gas in a chamber will improve the temperature, if the volume of the chamber stays the same or decreases. Decreasing the pressure will decrease the temperature. This is why a child’s balloon feels cold immediately after it is deflated, and why a bike pump will get warm if the tire is inflated quickly.
An air conditioning unit uses a fluid such as Freon that has a boiling point near the ambient temperature of a room. A compressor pressurizes Freon gas, raising the temperature. The hot gas then runs by having a condenser, which is like a radiator, and allows heat to escape into the surrounding air (this perhaps the unit is beyond your building). As the pressurized gas cools, it condenses back to a liquid. Now, it is at questionable, but room temperature. The liquid passes by using an expansion valve, which brings down the pressure, providing a cold blend of liquid and gas. This cold mixture runs by using an evaporator, which is like a radiator, but working in reverse. As hot air from the room blows over the cold coils, the fluid in the coils turns to warm gas, and the air is cooled and returned to the room via a duct. The warm Freon then returns to the compressor, and the cycle starts over.
In addition to cooling the air in a room, an air conditioning unit also brings down the moisture content. This is because as hot air from the room runs at night cold evaporator coils, moisture from the air condenses on the coils, much like water condenses on a cold glass on a hot day.
The Freon compressor requires a lot of power, in addition to the power necessary to run the fans that blow air over the evaporator and condenser. This means that an air conditioning unit is much more expensive to operate over a swamp cooler. But an air conditioning unit can operate and cool a place even when the air is humid, while a swamp cooler relies upon dry air to operate effectively.