Unformatted text preview: ated system. Surroundings ∆Ssys = –2 kJ/K
∆ Ssurr = 3 kJ/K
Sgen = ∆ Stotal = ∆ Ssys + ∆ Ssurr = 1 kJ/K Some Remarks about Entropy
In light of the preceding discussions, we can draw these conclusions: FIGURE 7–8
The entropy change of a
system can be negative, but
the entropy generation cannot. cen54261_ch07.qxd 11/18/03 9:57 AM Page 280 280
FUNDAMENTALS OF THERMAL-FLUID SCIENCES 1. Processes can occur in a certain direction only, not in any direction.
A process must proceed in the direction that complies with the increase
of entropy principle, that is, Sgen 0. A process that violates this
principle is impossible. This principle often forces chemical reactions
to come to a halt before reaching completion.
2. Entropy is a nonconserved property, and there is no such thing as
the conservation of entropy principle. Entropy is conserved during the
idealized reversible processes only and increases during all actual
processes. Therefore, the entropy of the universe is cont...
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