How Does a Fridge Work?

Take a look inside your Fridge...


Let’s take a look behind the scenes at the main mechanical parts that make sure your fridge keeps its cool.



To cool the food space we provide a very cold panel called the evaporator. It’s very cold because inside the evaporator coils is a liquid called a refrigerant. This liquid has a very low boiling point at the pressure in the coils. For more on boiling points and pressure see the pages on Boiling. The cold liquid absorbs the warmth from the air inside the refrigerator and turns into a low temperature gas, at low pressure. It now starts its journey to the compressor (Blue lines).



The pressure is kept low by pumping out the gas using the compressor. That’s what you can hear as it does its job. Just as air becomes warm when a tyre is pumped, so the high pressure refrigerant is warm when it leaves the compressor – indicated by the red lines.



It enters condenser coils at the back of the unit where it loses heat to the surroundings. The gas begins to condense into a liquid.


Ventilation fins

The cooling fins on the back of the fridge unit help to dissipate the heat.


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. More liquid boils as heat arrives from the cooled space. We are back to the beginning of the cycle.


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The diagram below shows the basic fridge components:


In this video you can see more about how a fridge works:

Circuit Diagram

Engineering or circuit diagrams are used to represent visually how these components work together in a schematic way.  The symbols used are standard across all engineering diagrams.

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