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Unformatted text preview: process can serve as an appropriate model
for actual processes. Also, isentropic processes enable us to define efficiencies
for processes to compare the actual performance of these devices to the performance under idealized conditions.
It should be recognized that a reversible adiabatic process is necessarily
isentropic (s2 s1), but an isentropic process is not necessarily a reversible
adiabatic process. (The entropy increase of a substance during a process as a
result of irreversibilities may be offset by a decrease in entropy as a result of
heat losses, for example.) However, the term isentropic process is customarily used in thermodynamics to imply an internally reversible, adiabatic
EXAMPLE 7–5 No irreversibilities
(internally reversible) No heat transfer
(adiabatic) s2 = s1 FIGURE 7–14
During an internally reversible,
adiabatic (isentropic) process, the
entropy remains constant. T Isentropic Expansion of Steam in a Turbine 1 Pa 5M Steam enters an adiabatic turbine at 5 MPa and 450°C and leaves at a pressure
of 1.4 MPa. Determine the work o...
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- Spring '09