Central Air Conditioner
All air conditioning systems reduce the temperature and adjust the
humidity of the air in the home to levels that provide a level of comfort.
The most common type of system used in the U.S. is the basic, air-cooled
central air conditioning system. Another type of system, found primarily in
the hot and arid areas such as the southwestern U.S., is known as an evaporator
cooler or “swamp cooler”. Other, less common types include the water-cooled systems, gas chillers and geothermal systems.
How They Work
The common, air-cooled central air conditioner removes heat
from the air in the home and moves the heat to the air on the exterior of the home.
Air conditioners accomplish this by taking advantage of the basic physical
law that heat moves to areas that are cooler. Heat from the interior of
the home is transferred to a refrigerant that carries the heat to the
exterior of the home. Currently the most effective refrigerant is
freon. The
warm air in the home is blown over an evaporator
coil that contains cold
(approximately 20 degrees F) freon liquid. The freon absorbs heat from the air in the
house, which cools the
air. The warmer (approximately 50 degrees F) freon, which has boiled and turned into
a gas, is then moved to the exterior of the home where it disperses
the heat.
The question is, "How is the heat dispersed when it is hot
outside?" A gas or liquid, when compressed, will have a higher temperature.
A compressor is used to compress the freon gas,
increasing its temperature by approximately 100 degrees F and causing the freon to become much
hotter than the air outside. The air outside (approximately 85 degrees F) can then
be blown over the condensing coil
that contains the hot freon (approximately 150 degrees F) . The air absorbs the heat from the
compressed freon, in effect cooling it. The cooled, but still compressed freon
(approximately 100 degrees F), is
then returned to the house. To lower the temperature of the freon liquid even more,
the freon is expanded or decompressed (to approximately 20
degrees F). The
freon is then once again ready to absorb the heat from the air in the home.
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