Question

How does a window air conditioner (AC) cool the room using only outside air and no water, like a refrigerator or dehumidifier?

Answer 1

A window air conditioner (AC) cools a room using a process called refrigeration, which is the same principle used in a refrigerator or a dehumidifier. Unlike evaporative coolers or swamp coolers, which use water to cool the air, window air conditioners do not rely on water for the cooling process.

Here's a simplified explanation of how a window air conditioner cools the room without using water:

1. Compression: The window AC unit contains a refrigerant, a chemical that easily changes from a gas to a liquid and vice versa. The cooling process begins with the compressor compressing the refrigerant gas, which causes it to become hot and high-pressure.

2. Condensation: The hot, high-pressure refrigerant gas then flows to the condenser coils located on the back or side of the AC unit. These coils release the heat from the refrigerant into the outside air, and as a result, the refrigerant condenses into a high-pressure liquid.

3. Expansion: The high-pressure liquid refrigerant is forced through an expansion valve, where it undergoes a rapid decrease in pressure. This causes the refrigerant to expand and turn into a low-pressure, cool mist-like liquid/gas mixture.

4. Evaporation: The cool mist-like refrigerant then flows through the evaporator coils located on the front of the AC unit, which are exposed to the indoor air. As the warm indoor air blows over the evaporator coils, the refrigerant absorbs heat from the air, causing the refrigerant to evaporate and turn back into a low-pressure gas.

5. Cooling effect: During the evaporation process, the refrigerant absorbs a significant amount of heat from the indoor air, effectively cooling it down. The now-cooled air is then blown back into the room, while the warm refrigerant gas is cycled back to the compressor to start the process again.

This continuous cycle of compression, condensation, expansion, and evaporation allows the window air conditioner to remove heat from the indoor air, cooling down the room without using water. The process remains enclosed within the AC unit and does not require any water to function. The heat extracted from the indoor air is transferred to the outside environment through the condenser coils, which is why the back or side of the window AC unit may feel warm when it's running.