How Modern Air Conditioning Works
Air conditioning a building has actually been in practice for centuries. In Ancient Roman society evidence has been found to show us that the residents would circulate water from the aqueduct throughout the walls in buildings to cool the interior. Modern day air conditioning has come a long way from water circulation in walls although currently we retain the same philosophies.
In 1902 Willis Haviland Carrier invented the first electric air conditioner for large buildings. His namesake would remain on certain models even to this day. The concept behind the operation of air conditioning a room or building is the same, while different models may operate a bit differently. There are window air conditioners that fit inside the window resting on the sill, rooftop units, ground units, geothermal units, and cooling towers just to name a few types.
Depending on the size of the area you wish to cool you may see anywhere from a single unit to multiple units used. When you get down to the bare nuts of the unit, you will find that an a/c works much like a refrigerator within an insulated box. When Freon evaporates it will provide the cooling. The evaporation cycle works like this: the compressor will cool the Freon gas which actually turns the gas hot; the hot gas will run through coils to get rid of the heat and it is condensed into liquid; the Freon liquid goes through an expansion valve while evaporating and the cold gas will go through coils that will let the gas absorb the heat and cool down the air.
Did you get that? In other words, every air conditioning unit will have a compressor to compress gas, an expansion valve so that the gas doesn’t explode, hot and cold coils, fans and of course a controller so you have the ability to turn it on and off. The fans will blow the air over the coils as they assist the coils in dispelling the hot air into the outdoors while helping the cool air spread further indoors. You will usually find the hot portion of an air conditioning unit outside while all things that cool remain inside the building. This holds true for a window, rooftop or ground level air conditioner.
When it comes to cooling towers it’s a bit different. Cooling towers used the chilled water method to cool the air. These are usually found on a roof or behind a building. Water is cooled to 40-45ºF (4.4-7.2ºC) and is then sent along a piping system throughout the building and is connected to air handlers where required. Also be aware of the fact that barometric pressure and relative humidity play a great part in the effectiveness of a cooling tower’s operation.
Portable air conditioning units work by way of cooled water being pumped in front of a fan for cooler air and some units allow for ice to be used as well.
You will find air conditioning units measured in BTUs and EER. The British Thermal Unit refers to the amount of heat needed to raise the temperature of a pound of water. Therefore a 1-ton air conditioner is 12,000 BTU. Window units are usually 10,000 BTU and a 5-ton unit for a decent sized family home is 60,000 BTU. The Energy Efficiency Rating refers to the wattage of the units.
The bottom line in defining air conditioning states that indoor air is cooled and dehumidified through the use of coils, compressors and fans. Now, sit back and enjoy the weather!
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