An air conditioning unit cools the air in a room using a process called refrigeration. The basic principles of how an air conditioner works are similar to those of a refrigerator. The main components of an air conditioning system are the compressor, condenser, expansion valve, and evaporator. Let's walk through the cooling process step by step:
Compression: The process begins with the compressor, which is typically located in the outdoor unit of the air conditioner. The compressor's role is to compress the refrigerant gas (often a hydrofluorocarbon or HFC) to increase its pressure and temperature. As the refrigerant is compressed, its molecules gain energy and become a high-pressure, high-temperature gas.
Condensation: The high-pressure, high-temperature gas from the compressor then moves to the condenser coil, which is also part of the outdoor unit. The condenser coil dissipates the heat from the refrigerant to the outside environment. As the refrigerant releases heat, it undergoes a phase change, transforming from a gas into a high-pressure liquid.
Expansion: The high-pressure liquid refrigerant now moves into the expansion valve or metering device, which is a small opening that restricts the flow of the refrigerant. This sudden reduction in pressure causes the refrigerant to expand rapidly, leading to a drop in temperature.
Evaporation: The cold, low-pressure liquid refrigerant now enters the indoor unit of the air conditioner, where it passes through the evaporator coil. The indoor unit is the part of the air conditioner that blows air into the room. As warm air from the room passes over the cold evaporator coil, heat from the air is absorbed by the refrigerant. This heat exchange causes the refrigerant to evaporate and turn back into a low-pressure gas.
Air Circulation: The now-cooled air is blown back into the room by the indoor unit's fan. At the same time, the heated refrigerant gas is carried back to the compressor through a closed-loop system to repeat the cycle.
By continuously circulating the refrigerant through this cycle, an air conditioning unit can maintain a cool and comfortable indoor environment. The process of removing heat from the room and transferring it outside is what allows the air conditioner to cool the air effectively. The thermostat in the air conditioner regulates when the compressor turns on and off to maintain the desired temperature in the room.