30 TRG-TRC003-EN
notes
period four
Pressure–Enthalpy Chart
The compressor draws in the superheated refrigerant vapor (&) and
compresses it to a pressure and temperature (') high enough that it can reject
heat to another fluid. As the volume of the refrigerant is reduced by the
compressor, its pressure is increased. Additionally, the mechanical energy used
by the compressor to accomplish this task is converted to heat energy. This
causes the temperature of the refrigerant to also rise as its pressure is
increased.
When the refrigerant vapor is discharged from the compressor, its temperature
is substantially higher than its saturation temperature (the temperature at
which the refrigerant would condense). The increase in enthalpy from & to ' is
due to heat added by the compressor, or the heat of compression.
In this example, the refrigerant leaves the compressor at 280 psia [1.93 MPa]
and 191.5°F [88.6°C]. At this higher pressure, the corresponding saturation
'
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Figure 46
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Figure 47