Refrigerators work based on the principles of thermodynamics and the circulation of refrigerant gases to remove heat from the inside of the fridge, thereby keeping the contents cool without the need for ice or external sources of coldness. The key components and processes involved in the operation of a refrigerator are as follows:
Refrigerant: The refrigerant is a special chemical compound that can change from a gas to a liquid and back again at specific temperatures. Common refrigerants used today include hydrofluorocarbons (HFCs) or hydrochlorofluorocarbons (HCFCs).
Compressor: The compressor is the heart of the refrigeration system. It is a motor-driven pump that compresses the refrigerant gas, increasing its pressure and temperature. This compressed hot gas is then sent to the condenser.
Condenser: The hot, high-pressure refrigerant gas flows into the condenser, usually a set of coils located on the back or bottom of the refrigerator. As the gas cools down, it condenses into a high-pressure liquid.
Expansion valve: The high-pressure liquid refrigerant now passes through an expansion valve, also known as a throttle valve. The valve restricts the flow, causing the refrigerant to rapidly expand. This expansion lowers the pressure and temperature of the refrigerant, turning it into a low-pressure, cold gas.
Evaporator: The cold refrigerant gas enters the evaporator, another set of coils typically located inside the refrigerator's main compartment. As the warm air from the fridge interior comes into contact with the cold evaporator coils, heat is transferred from the air to the refrigerant, causing the refrigerant to evaporate into a low-pressure gas once again.
Absorption of heat: The evaporation of the refrigerant in the evaporator absorbs heat from the surrounding air, cooling the inside of the refrigerator. This is similar to how sweat evaporating from our skin cools us down.
Compressor re-compression: The low-pressure gas now returns to the compressor to begin the cycle again. The process repeats continuously, maintaining a cool temperature inside the refrigerator.
By repeatedly circulating the refrigerant through the compressor, condenser, expansion valve, and evaporator, a refrigerator can remove heat from its interior, keeping the contents cool.
It's important to note that refrigerators do generate some heat in the process of removing heat from the inside. This is why you might notice the area around the refrigerator feels warmer. The overall result, however, is a net reduction in the temperature inside the refrigerator, preserving food and keeping it fresh for longer periods without the need for ice or other external cooling sources.