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between the two states. The integral of dQ/T along an irreversible path is not
a property, and in general, different values will be obtained when the integration is carried out along different irreversible paths. Therefore, even for irreversible processes, the entropy change should be determined by carrying out
this integration along some convenient imaginary internally reversible path
between the specified states. T 0.3 S2 S, kJ/K FIGURE 7–3
The entropy change between two
specified states is the same whether
the process is reversible or
irreversible. A Special Case: Internally Reversible
Isothermal Heat Transfer Processes
Recall that isothermal heat transfer processes are internally reversible. Therefore, the entropy change of a system during an internally reversible isothermal cen54261_ch07.qxd 11/18/03 9:57 AM Page 277 277
CHAPTER 7 heat transfer process can be determined by performing the integration in
Eq. 7–5:
2 S
1 Q
T 2
int rev 1 Q
T0 int rev 1
T0 2
1 (dQ)int rev which reduces to
S Q
T0 (kJ/K) (7–6) where T0 is the constant absolute temperature of the system and Q is the heat
transfer for the internally reversib...
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This document was uploaded on 11/28/2012.
 Spring '09

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