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Fridges are lined with pipes which contain a refrigerant gas built into the insulation, or, on a plate at the rear wall of the fridge interior.They also have pipes on the outside of the back wall of the fridge which works as a heat exchanger, normally called the condenser.
The basic mechanism of a refrigerator works by transforming the refrigerant gas into a liquid and back into a gas to create repeated evaporation of the refrigerant every time the compressor runs, this cycle occurs. It is this evaporation process that produces low temperatures & therefore cools the fridge interior. All fridges have a compressor, it is this small engine that you can hear as the fridge cycles on and off. The compressor creates a pressurized environment in part of the fridge. Under pressure the refrigerant warms up – the condenser heats up - & the pressure increases. The heat exchanging pipes outside the fridge allow the heat to be dissipated and as it cools the gas turns to liquid form and runs through into the coils inside the fridge which is a comparatively low-pressure area.
As the refrigerant expands it evaporates thus absorbing heat and cooling the inside the fridge before repeating the cycle. Freezers also work on the same principle as above, except there is more piping & therefore, lower temperatures are achieved. |