How Does A Chest Freezer Work?

Have you often wondered how your chest freezer works? Just how can it maintain temperatures as low as -18 degrees for an average running cost of around 15p per day?

We realised the need for refrigeration back in prehistoric times when people would gather ice in winter and store it in cool, dark caves or insulated dugouts for when the warmer weather arrived.

Luckily things have advanced a bit since then, although the basic principle of keeping items cool in an insulated container remains.

The Basics

Refrigeration works based on the principle of removing heat from the inside of a fridge or freezer to keep the contents cool. It operates using a fluid called refrigerant that can easily change from a liquid to a gas and back again. We can break the process down into 5 steps:

Compression
The process starts with a compressor, which is like the heart of the system. The compressor squeezes the refrigerant gas, raising its temperature and pressure. This high-pressure gas then moves to the next step.

Condensation
The hot, high-pressure gas flows through coils at the back or bottom of the fridge or freezer. These coils release the heat into the surrounding air, causing the refrigerant gas to condense and become a high-pressure liquid.

Expansion
The high-pressure liquid refrigerant then passes through an expansion valve or capillary tube. As it rapidly expands through this valve, it becomes a low-pressure liquid-gas mixture. This process causes the refrigerant to evaporate and cool down significantly.

Evaporation
The low-pressure refrigerant flows inside the coils or pipes located inside the fridge or freezer. When it comes into contact with the warm air inside the compartment, it absorbs the heat, causing it to evaporate and turn back into a low-pressure gas.

Return to the Compressor
The low-pressure gas returns to the compressor, and the cycle starts again. This continuous cycle of compression, condensation, expansion, and evaporation keeps repeating, creating a cooling effect inside the fridge or freezer.

By removing heat from the inside and releasing it outside, the refrigerator maintains a lower temperature inside, keeping your food and drinks fresh and cool.

Read more about the history and workings of refrigeration on this very informative Wikipedia page: