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Unformatted text preview: during the process. We note that the temperature of the system remains constant at 300 K during this process since the temperature of a pure
substance remains constant at the saturation value during a phase-change
process at constant pressure.
Assumptions No irreversibilities occur within the system boundaries during the
Analysis The system undergoes an internally reversible, isothermal process,
and thus its entropy change can be determined directly from Eq. 7–6 to be Ssys, isothermal Q
Tsys 750 kJ
300 K I Q = 750 kJ FIGURE 7–4
Schematic for Example 7–1. 2.5 kJ/K Discussion Note that the entropy change of the system is positive, as expected, since heat transfer is to the system. 7–2 Q
= 2.5 kJ
T Process 1-2
irreversible) 2 THE INCREASE OF ENTROPY PRINCIPLE Consider a cycle that is made up of two processes: process 1-2, which is
arbitrary (reversible or irreversible), and process 2-1, which is internally
reversible, as shown in Fig. 7–5. From the Clausius inequality,
T 0 1 Process 2-1
reversible) FIGURE 7–5
A cycle composed of a reversible
and an i...
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- Spring '09