Chapter 7

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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 nozzle inlet. 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 7–29 Refrigerant-134...
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This document was uploaded on 11/28/2012.

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