16 TRG-TRC003-EN
notes
period two
Refrigerants

Modern Refrigerants

Refrigerants are substances that are used to absorb and transport heat for the
purpose of cooling. When selecting a refrigerant to use for a given application,
in addition to these heat transfer properties the manufacturer considers
efficiency, operating pressures, compatibility with materials, stability, toxicity,
flammability, cost, availability, safety, and environmental impact.
The most common refrigerants used in mechanical refrigeration systems today
are Refrigerant-123 (or R-123), R-134a, and R-22. Ammonia (R-717) and, under
certain operating pressures, even water (R-718) and carbon dioxide (R-744) can
be used as refrigerants.
Refrigerant-22 has been the most widely used refrigerant in residential,
commercial, and industrial applications since the 1940s. For the purposes of
this clinic, it will be used as the refrigerant in the examples.
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Figure 26