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The increase of entropy principle does not imply that the entropy of a system cannot decrease. The entropy change of a system can be negative during
a process (Fig. 7–8), but entropy generation cannot. The increase of entropy
principle can be summarized as follows:
Sgen (Isolated) 0 Irreversible process
0 Reversible process
0 Impossible process This relation serves as a criterion in determining whether a process is reversible, irreversible, or impossible.
Things in nature have a tendency to change until they attain a state of equilibrium. The increase of entropy principle dictates that the entropy of an isolated system will increase until the entropy of the system reaches a maximum
value. At that point, the system is said to have reached an equilibrium state
since the increase of entropy principle prohibits the system from undergoing
any change of state that will result in a decrease in entropy. System
Q, W m Surroundings FIGURE 7–7
A system and its surroundings
form an isol...
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This document was uploaded on 11/28/2012.
- Spring '09