When you step into an air-conditioned room on a hot summer day, the difference is striking. But how is the air cooled?
An air-conditioning system functions in the same way as a refrigerator. But where the refrigerator cools only a small, limited space, air conditioning can cool an entire house, shop or office. This is due to the physical principle of evaporation: When a liquid evaporates, it will absorb some of the heat from its surroundings.
A liquid refrigerant is directed into an evaporation system in which the pressure is low. This causes the refrigerant to evaporate into a gas, cooling the large surface area of the coils of the system. The cooler air that is created is sent into the room via a blower.
The process will generate heat, so air conditioning has both a cold and a warm function. Cold air may contain less moisture than warm air, so the system will generate condensation, which is removed. On hot days, an air conditioner may drip.
Our ancestors were subjected to the relentless Middle Eastern heat all year, and they had to find shelter from it. They solved the problem by living in caves cooled by the surrounding earth or rock layers. The cave effect was later copied in multistory houses with thick stone walls and deep basements.
Air Conditioning step by step
1 – A liquid refrigerant is directed through an expansion valve into a pipe, where the pressure is low.
2 – The refrigerant evaporates into a gas. Heat is absorbed from the surroundings, cooling the pipes.
3 – A blower directs the cooled air into the room.
4 – The gas is directed through a compressor, which increases the pressure, making the gas liquid.
5 – In the process, heat is generated; it is blown outside by a fan via pipes on the opposite side.
6 – A thermostat turns off the system when the air inside is sufficiently cooled.