An air conditioner and a refrigerator work based on the same fundamental physical principle, which is the principle of thermodynamics. Specifically, they rely on the process of refrigeration to transfer heat from a colder region (inside the refrigerator or conditioned space) to a warmer region (outside the refrigerator or conditioned space).
The primary components involved in the operation of an air conditioner or refrigerator are a refrigerant, a compressor, a condenser, an expansion valve (or throttle valve), and an evaporator.
Refrigerant: The refrigerant is a substance that has a low boiling point and can change between liquid and gaseous states easily. Commonly used refrigerants are hydrofluorocarbons (HFCs) like R-134a or R-410A. In the past, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were used, but due to their environmental impact, they are now largely phased out.
Compression: The process starts with the compressor, which is responsible for pressurizing the low-pressure, low-temperature gaseous refrigerant. By compressing the gas, its temperature and pressure increase significantly.
Condensation: The high-pressure, high-temperature gas then flows into the condenser coils, usually located outside the refrigerator or air conditioner. Here, the hot gas releases heat to the surrounding environment and condenses into a high-pressure liquid.
Expansion: The high-pressure liquid passes through the expansion valve (or throttle valve), which restricts its flow and reduces its pressure suddenly. As the pressure drops, the refrigerant's temperature also decreases.
Evaporation: The low-pressure, low-temperature liquid refrigerant now enters the evaporator coils, typically located inside the refrigerator or air conditioner. As it evaporates, it absorbs heat from the surrounding air, causing the air to cool down.
Circulation: The cycle repeats as the low-pressure, low-temperature gaseous refrigerant returns to the compressor to start the process again.
By continuously cycling the refrigerant through these stages, the air conditioner or refrigerator can remove heat from the conditioned space (inside) and release it to the external environment (outside). This process of heat transfer is what keeps the inside of the refrigerator cold and the conditioned space comfortable in the case of an air conditioner.