Cold production is based on a fairly simple principle. The idea is to compress a steam obtained at low temperatures, in order for it to condense through the rejection of heat into the natural environment.
Practically, a refrigeration system allows to cool down an environment at a lower temperature than its surrounding atmosphere. Since naturally heat always travels from a warm body to a colder one, we can define a refrigeration system as a device that allows you to turn around heat conveyance. Energy then travels from a cold to a warmer environment. This reversed transfer will of course require some energy input.
The objective of a refrigeration system is then to transfer a heat quantity from a low temperature environment (the cold source) to a high temperature environment (the warm source).
The system absorbs heat at the cold source (thus produces cold) and transmits this heat to the warm source (thus produces heat). If the intended result is the production of heat, the device is then called a heat pump.
A heat pump is in fact a cooler that is used backwards. In a refrigerator, the intended effect is the production of cold, in other words the absorption of heat from the food placed inside the refrigerator. The cooling circuit allows this heat transfer. A heat pump works according to exactly the same principle as a refrigerator.
A refrigeration system allows to transfer heat from a cold environment to a warm environment thanks to a compression system. Such a refrigeration system usually consists of four elements: