To pull off this frosty feat, a refrigerator uses five major components:
- Compressor
- Heat-exchanging pipes (serpentine or coiled set of pipes outside the unit)
- Expansion valve
- Heat-exchanging pipes (serpentine or coiled set of pipes inside the unit)
- Refrigerant (liquid that evaporates inside the refrigerator to create the cold temperatures)
Alternative cooling methods to common expansion-compression systems; Peltier effect, a thermoelectric effect, to produce cold temperatures.
Absorption | A process in which energy (heat) is taken up by a liquid or solid. |
Compressor | This is a pump which compresses refrigerant gas, and consequently heats the gas. |
Condensation | A change of state from gas or vapour to liquid. |
Evaporation | A change of state from solid or liquid to gas or vapour. It occurs when some molecules of a liquid have enough energy to escape into the gas phase and this has an overall cooling effect on the liquid. |
Expansion | The increase of volume of a sample of substance. |
Refrigerant | A chemical substance used as a fluid in a refrigeration system. There are many different types of fluid used, depending on the system design. |
Refrigeration | This is the transfer of heat from a substance to be cooled to somewhere else. Heat flows naturally from a warm substance to a colder one eg fish can be cooled by surrounding it with packing ice. |
Restrictor | Something that restricts the flow of a gas or liquid. |
Sublimation | This is when a solid turns to vapour without going through the liquid phase. For example, you can see solid carbon dioxide (CO2) turning to vapour when it melts without producing a liquid (dry ice). |
Thermal Insulation | A means of preventing or reducing the transfer of thermal energy (heat). Good insulators are foam, wool, and vacuums. |
Vapour | A substance in a gas state that has reached a temperature at which it could become a liquid just by the application of pressure. It is usually still in contact with the liquid from which it was formed. |
Visit ‘Fantastic Fridges’ for more information, interactive animations and games: Fantastic Fridges
For more technical detail on the science and further learning, Danfoss ‘Basics of Refrigeration’ PDF