Friday, 16 January 2015


How your refrigerator cools the food you put inside it ?

This is a good practical example of the gas laws in action.Temperature , Pressure and Volume all have a part to play in the cooling process.

Firstly , Gas ( generally Ammonia ( NH3 ) ) is drawn at low pressure and low temperature through a line.

The gas is compressed using electricity to a higher pressure and its temperature rises  ( just like a bicycle pump which gets warmer when you are pumping up a tyre.

It is then transferred to a condenser where the heat is removed and the gas begins to condense into a liquid.

The heat is released via cooling fins on the back of the refrigerator unit.

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 vapours.

This change of state has a cooling effect.Now the cold vapour and vapours are able to cool the air in the cabinet of the refrigerator through an evaporator.

The cold liquid absorbs the warmth or heat 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.

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