Liquid chillers. Ice. Brines. Thermal storage

A building or process having a large number of separated cooling loads could have a refrigeration system for each of these loads. It will usually be more convenient to concentrate the cooling into one plant. 

The cooling effect of a central refrigerating system can be distributed by a heat-transferring liquid or secondary refrigerant. 

Where the working temperatures are always above 0°C, such as in air-conditioning, water is commonly used. At temperatures below this, non-freezing liquids are used. 

The preferred secondar yrefrigerant will be water, if this can possibly satisfy the temperature requirement, i.e. if the load temperature is sufficiently above 0°C that water can be circulated without risk of freezing. 

At water temperatures close to freezing, and with evaporators 

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