How do fridges use gas behaviour to cool food?

Fridges use the behaviour of gases to cool food by compressing and expanding a refrigerant gas in a closed system.

In more detail, the cooling process in a fridge is based on the principles of gas behaviour, specifically the principles of pressure, temperature, and volume, which are described by the ideal gas law. This law states that the pressure of a gas is directly proportional to its temperature if the volume is kept constant, and inversely proportional to its volume if the temperature is kept constant.

The fridge operates using a refrigeration cycle, which involves a refrigerant gas circulating through a series of tubes and components. The cycle begins with the refrigerant gas being compressed by the compressor. This increases the pressure and temperature of the gas, turning it into a high-pressure, high-temperature gas.

This hot gas then flows into the condenser coils located at the back of the fridge. Here, the gas releases its heat to the surrounding environment, causing it to cool down and condense into a high-pressure liquid.

The high-pressure liquid refrigerant then passes through an expansion valve, which reduces its pressure. This sudden drop in pressure causes the refrigerant to evaporate and become a low-pressure gas, a process that absorbs heat and cools the surrounding area.

This low-pressure, cold gas then enters the evaporator coils inside the fridge. As it flows through these coils, it absorbs heat from the food and other items in the fridge, cooling them down. The gas then returns to the compressor, and the cycle begins again.

In this way, fridges use the behaviour of gases to transfer heat from inside the fridge to the outside environment, effectively cooling the food and other items inside.