Air conditioners work on the principle of refrigeration, which involves the circulation and phase change of a refrigerant, usually in the form of a liquid and a gas. The refrigerant used in most modern air conditioners is a chemical compound with properties that allow it to absorb heat from one place and release it in another. The process of cooling down a space with an air conditioner can be summarized in these steps:
Compressor: The air conditioning process starts with the compressor. The compressor is responsible for pressurizing the low-pressure, low-temperature gaseous refrigerant coming from the evaporator coil. As the refrigerant is compressed, its temperature and pressure increase significantly.
Condenser Coil: The hot, high-pressure gas refrigerant then flows into the condenser coil located on the outside of the air conditioning unit or the back of a window unit. The condenser coil helps to dissipate the heat from the refrigerant, causing it to condense and transform back into a high-pressure liquid.
Expansion Valve: From the condenser, the high-pressure liquid refrigerant moves into the expansion valve (also known as the throttling valve). The expansion valve is a small opening that allows the high-pressure liquid refrigerant to suddenly expand, leading to a drop in pressure. This rapid pressure drop causes the refrigerant to become a low-pressure, low-temperature mixture of liquid and vapor.
Evaporator Coil: The low-pressure, low-temperature refrigerant then enters the evaporator coil located inside the indoor unit of the air conditioner. The warm indoor air from the room is blown over the evaporator coil by a fan, and as the air passes over the cold coil, heat is transferred from the air to the refrigerant. This heat transfer process cools down the air, and the refrigerant absorbs the heat, causing it to evaporate and turn into a low-pressure gas.
Blower Fan: The cooled air is then blown back into the room, reducing the room's temperature.
Refrigerant Cycle: The gaseous refrigerant now returns to the compressor, and the cycle continues as long as the air conditioner is running. The refrigerant continuously absorbs heat from the indoor air and releases it to the outdoor environment through the condenser coil.
This continuous cycle of compression, condensation, expansion, and evaporation enables the air conditioner to cool down indoor spaces effectively. The liquid-gas phase change of the refrigerant is a crucial part of the process, as it allows the air conditioner to absorb heat from the indoor air and transfer it outside, thereby cooling the indoor environment.