How Does a Fridge Work?


Have you ever wondered how your fridge works to keep things cold?

Refrigerators use the principles of pressure, condensing and evaporation of a fluid in a closed circuit to remove heat and reduce the temperature inside the fridge.  

The fluid is called the refrigerant and the picture shows how it is moved around the circuit to cool the space in the fridge.

You can see in the diagram opposite the different components that make a fridge work and how they fit into the cabinet.

Compressor: Gas at low pressure and low temperature enters the compressor. The gas is compressed to a higher pressure and its temperature rises (just like a bicycle pump which gets warmer pumping up a tyre).This uses electricity.

Condenser: The hot gas is then transferred to a condenser where the heat is removed and the gas begins to condense into a liquid.

Ventilation fins: The heat is released via cooling fins on the back of the fridge unit

Expansion valve: The liquid then goes through an expansion device where its pressure is suddenly lowered, it expands and some of the liquid turns very quickly into a vapour. This change of state has a cooling effect.

Evaporator: The cold liquid absorbs the warmth from the air inside the refrigerator and turns back into a low temperature gas, at low pressure. It now starts its journey again through the compressor.

Think you've got all that? Why not try our refrigeration circuit test game 


Fridge Circuit Diagram

Pressure, temperature, volume

Fridge circuit test

Young Learners Overview