Components of Refrigeration Systems

Refrigeration compressor

The refrigeration process is, as implied, a closed
circuit. The refrigerant is not allowed to expand to
free air.
When the refrigerant coming from the evaporator
is fed to a tank the pressure in the tank will
rise until it equals the pressure in the evaporator.
Therefore, refrigerant flow will cease and the temperature
in both tank and evaporator will gradually
rise to ambient.
To maintain a lower pressure, and, with it a lower
temperature it is necessary to remove vapour.
This is done by the compressor, which sucks vapour
away from the evaporator. In simple terms,
the compressor can be compared to a pump that
conveys vapour in the refrigeration circuit.
In a closed circuit a condition of equilibrium will
always prevail. To illustrate this, if the compressor
sucks vapour away faster than it can be formed in
the evaporator the pressure will fall and with it
the temperature in the evaporator. Conversely, if
the load on the evaporator rises and the refrigerant
evaporates quicker, the pressure and with it
the temperature in the evaporator will rise.