PRINCIPLE OF COMPRESSION CYCLES FOR REFRIGERATION OR HEAT-PUMPING

Such a refrigerator consists of:

* a COMPRESSOR, most often electrically powered,

* an EVAPORATOR (the "freezer") enclosed in an insulated cold box,

* a CONDENSER (the "grid" behind your refrigerator),

* and a Expansion VALVE.

Up to the recent regulations, the usual refrigerants were R 134a or

R 404a ..etc.. However, because of the ozone layer depletion and global warming problems, more and more substitutes are under development.
In the cycle, the refrigerant follows four steps:

1: Compression
The vapour is compressed and its temperature increases

2: Condensation
The fluid at "high pressure" is cooled by ambient air, which induces its condensation

3: Expansion
The liquid is depressurised and its temperature decreases

4: Evaporation
The fluid at "low pressure" receives heat at low temperature, which induces its vaporisation.

Typically, for domestic refrigeration, the coefficient of performance (COP) of compression cycles lies around 3.