The Air Conditioner – A Primer
So How Does An Air Conditioner Work?
The air conditioner – it’s perfect for relief from a hot summer’s day and we are all familiar with the refreshingly cool end result.
While air conditioners come in all shapes and sizes, they all rely on the same principle – the refrigeration cycle. As the name implies, air conditioners are basically open refrigeration systems. The process can get fairly technical, but I’ll break it down so you can easily grasp the concept.
The idea of air conditioning revolves around the liquid to gas phase change. Think of it this way. When you are hot, you sweat (liquid) and when the sweat evaporates (gas), you cool down. This is the basic premise of the air conditioner.
The Parts of the Air Conditioner
To understand how the air conditioner works, we will take a look at the common window air conditioner. This particular unit is made up of six main parts: inside blower, outside fan, the condenser coil, the evaporator coil, the expansion valve and the compressor. There is a constant liquid to gas, gas to liquid phase conversion within these parts that produce the air conditioning effect. Throughout the coils, there is a liquid/gas substance called a refrigerant that is constantly moving around.
The Air Conditioning Process
Pulling Out the Hot Air, Blowing in the Cool
1. A blower pulls out the hot air from the room (into the evaporator coils facing the room) while simultaneously blowing in cool air off the evaporator coils. The evaporator coil, which is usually made of a metal that easily absorbs heat, such as copper, then transfers the heat into the refrigerant liquid (usually a fluorocarbon) which is situated at 35.6 degrees Fahrenheit.
2. As the liquid absorbs more heat, it will turn into a gas. The gas will move up its way in the coil where it then gets processed in the compressor which is the device that is responsible for pushing the refrigerant through the coils in the air conditioner (it also makes the humming noise).
Getting Rid of the Heat
3. The compressor compresses the ‘cool’ low pressure gas at high pressure. As a byproduct of this stage in the process, the gas becomes much hotter reaching a temperature of 150 degrees Fahrenheit. At this point, the refrigerant is pushed through the condenser coils that face the outside air.
4. The gas will ‘meet’ with the ‘cooler’ refrigerant (that’s roughly the temperature of the outside air) in the condenser coils and turn into liquid. The refrigerant will then be passed through the expansion valve (aka metering device and is what controls the flow of the refrigerant) to lower the pressure and further cool the now liquid refrigerant. During this process, the back fan pushes the hot air out.
5. The cooled liquid refrigerant is then circulated back in towards the evaporator coil so the blower can circulate the cool air into the room. Wash, Rinse, and Repeat.
This describes the typical window air conditioner system, but the same basic principle applies to all types of air conditioners whether they are split-system, chilled water or cooling-tower AC units.
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