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Unformatted text preview: entropy of a
system (always, sometimes, never) increases.
7–21C Is it possible for the entropy change of a closed
system to be zero during an irreversible process? Explain. cen54261_ch07.qxd 11/18/03 9:58 AM Page 335 335
CHAPTER 7 7–22C What three different mechanisms can cause the entropy of a control volume to change?
7–23C Steam is accelerated as it flows through an actual
adiabatic nozzle. The entropy of the steam at the nozzle exit
will be (greater than, equal to, less than) the entropy at the
7–24 A rigid tank contains an ideal gas at 40°C that is being
stirred by a paddle wheel. The paddle wheel does 200 kJ of
work on the ideal gas. It is observed that the temperature of the
ideal gas remains constant during this process as a result of
heat transfer between the system and the surroundings at 30°C.
Determine the entropy change of the ideal gas. determine (a) the amount of heat transfer, (b) the entropy
change of the sink, and (c) the total entropy change for this
process. Answers: (a) 388.5 Btu, (b) 0.7 Btu/R, (c) 0
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This document was uploaded on 11/28/2012.
- Spring '09