TRG-TRC003-EN 25
period three
Refrigeration Cycle
notes
The high-pressure liquid refrigerant (') flows through the expansion device,
causing a large pressure drop. This pressure drop reduces the refrigerant
pressure, and, therefore, its temperature, to that of the evaporator. At the lower
pressure, the temperature of the refrigerant is higher than its boiling point. This
causes a small portion of the liquid to boil, or flash. Because heat is required to
boil this small portion of refrigerant, the boiling refrigerant absorbs heat from
the remaining liquid refrigerant, cooling it to the desired evaporator
temperature.
The cool mixture of liquid and vapor refrigerant then enters the evaporator ($)
to repeat the cycle.
Placing each component in its proper sequence within the system, the
compressor and expansion device maintain a pressure difference between the
high-pressure side of the system (condenser) and the low-pressure side of the
system (evaporator).
This pressure difference allows two things to happen simultaneously. The
evaporator can be at a pressure and temperature low enough to absorb heat
from the air or water to be cooled, and the condenser can be at a temperature
high enough to permit heat rejection to ambient air or water that is at normally
available temperatures.
These major components are discussed in further detail in the “Refrigeration
Compressors” and “Refrigeration System Components” clinics.
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Figure 39
