How does a refrigerator work? Understandable explanation

Nowadays, a refrigerator belongs in every kitchen to make perishable foods such as meat and sausages more enjoyable. This article explains how the device works.

How does a refrigerator work?

In refrigerators and freezers, the refrigerated goods (i.e. perishable food or medication) are stored in a heat-insulated room, far below the ambient temperature. The average temperature in refrigerators is 4 - 8 ° C, in freezers it is -16 ° to -20 ° C. So-called compressor refrigerators are mainly used as household appliances:

• Since heat always flows from the warmer to the colder object, a heat transfer medium (refrigerant) is required. This is cooled below the desired cooling temperature and can thus absorb and remove the heat from the goods to be cooled. So that the refrigerant can give off heat to the environment, it is heated outside the cold room and the heat flows to the ambient air. Therefore, a cooling device must always be well ventilated (even in a fitted kitchen).
• The refrigerant is cooled by evaporation (transition from the liquid to the gaseous state), the heating by compression. Liquids are used as refrigerants that quickly change from gaseous to liquid and vice versa. These processes are only possible in a closed coolant circuit. Both forms of coolant are separated in this circuit by the compressor on the one hand and by a so-called throttling in the transition from the inside to the outside. Evaporation therefore takes place in the interior of the refrigerator, the very cold, liquid refrigerant changing into the gaseous state via the heat absorbed. On the outside, the compressor increases the density of the gas and thereby heats it. When the heat is released, the refrigerant can condense again (liquefy). The throttling causes a sudden reduction in the pressure in the liquid phase and thus the desired cooling.
• Since warmer air always rises, a distinction should be made between certain cold zones in the refrigerator despite setting a certain cooling temperature: after that, it is the coldest in the vegetable compartment and significantly warmer at the top. The correct storage location for meat and sausage products is above the vegetable compartment, and dairy products are stored above. The vegetable compartment below is tempered a few degrees higher; Butter, eggs and drinks can be stored in the door.