Refrigerators are one of the most vital household appliances, keeping food cool and fresh. But how do they work?
To achieve their cooling effect fridges rely on the simple notion of evaporation, absorbing heat when a liquid changes its state. This evaporation is the central principle of the refrigeration cycle, a perpetual loop in which a refrigerant is forced to change state in order to invoke heat absorption.
The cycle begins with the refrigerant in a vapour state, which is then pressurized in an internal compressor. This compression forces the refrigerant to heat up before being sent outside the fridge into a condenser and expelled into the surrounding area, cooling the refrigerant vapour in the process and condensing it into a highly pressurized liquid state.
This liquid is then sucked through an expansion valve and back into the low-pressure fridge compartment causing the refrigerant to boil (refrigerants have low boiling points), vaporize and drop in temperature, cooling the compartment in the process. The cycle then begins again, with the low-pressure refrigerant vapour being sucked up into the compressor.
1. Vapour – At the beginning of the cooling cycle, the refrigerant is in vapour state.
2. Compressor – An internal compressor then pressurizes the vapour, heating it up massively in the process.
3. Condenser – Once hot and highly pressurized the vapour is channeled outside the fridge into a condenser, cooling it into a high-pressure liquid.
4. Expansion valve – Once condensed, the liquid refrigerant is sucked into an expansion valve and back into the low-pressure fridge compartment, causing it to boil.
5. Compartment – As it boils (refrigerants have low boiling points) the refrigerant vaporizes and cools the main compartment of the fridge before being sucked back into the compressor to begin the cycle again.