How Does Air Conditioning Work?

How often do you drive past a home or other building and notice the air conditioner? Probably never, unless it is a window air conditioner that looks like it doesn't belong there. True air conditioning means not only controlling the temperature, but reducing the humidity and purifying the air. Air-cooling is simply forcing cool or cold air into a room, space or building. For the purpose of this article, the terms will be interchangeable. The simplest way to describe it works is the same way your refrigerator keeps food cold.

That would be a fair enough explanation, if you know how a refrigerator keeps things cool. You do know that almost everyone has a refrigerator. You know they make a very quiet noise every few minutes. You know things stay cold and fresh longer. The refrigerator isn't that complex. It circulates a refrigerant through a system of coils. The noise you hear is a compressor. The compressor compresses the gas refrigerant into a liquid. The liquid then moves through the coils and absorbs heat. We will go into greater detail shortly.

Many homes have air conditioner units in the back or side yard. Some have the window air conditioner, which is effective for cooling a smaller area. Office buildings and other larger buildings have the units on the roof or in large metal structures containing a system.

No matter what the size or the shape, most all air conditioners function the same way. As we said, it works essentially the same as your refrigerator. The principal is evaporation. Both the refrigerator and the air conditioner unit use a refrigerant that, in its normal state, is a gas. The gas may be one of several types or composition, but it is commonly referred to as Freon. The process of cooling the inside of a refrigerator, or for an air conditioner to cool a building space, is a cycle.

The first piece of the air conditioning system is the compressor. The compressor does just that, it compresses the refrigerant gas. The process makes the refrigerant become hot and, of course, under pressure. The now hot gas circulates through coils on the outside of the refrigerator or building and dissipates the heat. The heat dissipating cools the refrigerant gas back into a liquid. After the refrigerant becomes a liquid it goes through another piece of the system called an expansion valve. Running through the expansion valve produces evaporation and the refrigerant becomes cold and at low pressure. The cold gas continues through the interior of the refrigerator or building via coils. The cold, low-pressure refrigerant attracts and absorbs heat inside a refrigerator. In an air conditioner, a fan propels the cold air throughout the area or building. The cycle starts then all over again.

There is little doubt that most people look at air conditioning and air cooling as a welcome miracle. It is a simple process of converting a refrigerant gas to a hot liquid under pressure, then changing it to a low pressure-cooling agent to absorb heat; keeping us and our food cool.