Last edited 04 Mar 2021

Compression refrigeration

Refrigerants are used in buildings:

For heating, ventilation and air conditioning (HVAC) systems.
To provide cooling for refrigeration.
To provide cooling for industrial processes.

They provide cooling in a process that is essentially the same as that used in domestic fridges, based on either compression or absorption. Compression refrigeration is more common than absorption refrigeration.

In absorption refrigeration systems, a refrigerant that boils at low temperature and pressure is absorbed in a solution which is then heated in a ‘generator’ so that the refrigerant evaporates again, but this time at a higher pressure and temperature. The gas is then condensed, releasing its latent heat which is rejected. The process then repeats. See absorption refrigeration for more information.

In compression refrigeration, a circulating liquid refrigerant (such as a hydrofluorocarbon HFC) with a low boiling point absorbs heat from the body that is being cooled and boils in an evaporator to form a gas. The resulting gas is then compressed, which increases its temperature further. The gas is then condensed, releasing its latent heat which is rejected. The process then repeats.

The four primary components of a compression refrigeration system are:

The compressor.
The condenser.
The metering device (which maintains the refrigerant in its condensed state and feeds it to the evaporator).
The evaporator.

Typically in heating, ventilation and air conditioning systems, compression refrigeration takes place in chiller units which supply chilled water to the building that is in turn used to cool ventilation air in air handling units. Heat recovery can be used to allow the rejected heat from chiller units to be re-used for space heating or to provide hot water.