TRG-TRC003-EN 17
notes
period three
Refrigeration Cycle
The frozen display case example used in the last period demonstrates that, at a
given pressure, refrigerants absorb heat and change phase at a fixed
temperature. It also shows how these refrigerants are “consumed” in the
cooling process, either melting into a liquid or evaporating into a vapor.
This period discusses how the refrigerant can be recovered and reused to
continue the refrigeration cycle.
A rudimentary refrigeration system could hypothetically be constructed using a
drum of liquid refrigerant at atmospheric pressure, a coil, a collecting drum,
and a valve to regulate the flow of refrigerant into the coil. Opening the valve
allows the liquid refrigerant to flow into the coil by gravity. As warm air is
blown over the surface of the coil, the liquid refrigerant inside the coil will
absorb heat from the air, eventually causing the refrigerant to boil while the air
is cooled. Adjustment of the valve makes it possible to supply just enough

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