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The refrigeration cycle
In a typical refrigerator, heat is absorbed from the chilled space into a liquid (the refrigerant or coolant) by the evaporator.
This heat turns the coolant into a low-pressure gas that flows away from the evaporator to the compressor where it is pressurised. The gas gives up its stored heat (releasing it to the outside air) and condenses back to a liquid. It flows through to an expansion valve where pressure is released, cooling the liquid.
The compressor also pumps liquid and gas around the system. Usually the condenser, expansion valve and compressor are outside the refrigerated space. Key to effective, energy-efficient operation is ensuring that as much heat as possible enters through the evaporator and escapes from the condenser, and that the refrigerant flows efficiently around the system.
Types of systems
There are many different types of refrigeration system to suit the wide range of cooling needs in commerce and industry. For example:
- Many small businesses
will find a regular domestic refrigerator or freezer to be sufficient.
- Retail businesses often have chiller cabinets, or display fridges/freezers.
- Larger catering/food & drink operations may have ‘industrial’ chillers, or even cold rooms.
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