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| 1 | |
Saturated water vapor at 150 kPa is condensed to saturated liquid in a steady-flow, isobaric heat exchanger. The released heat is transferred to the surrounding air whose temperature is 20°C. The increase of the entropy associated with this process is |
| | A) | -4.731 kJ/kg-K |
| | B) | -2.366 kJ/kg-K |
| | C) | 2.366 kJ/kg-K |
| | D) | 4.731 kJ/kg-K |
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| 2 | |
Steam at 2 MPa, 300°C is expanded in a steady-flow, adiabatic turbine to 30 kPa. What is the lowest possible temperature at the outlet of this turbine? |
| | A) | 69.1°C |
| | B) | 101.1°C |
| | C) | 150.7°C |
| | D) | 203.2°C |
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| 3 | |
Steam at 2 MPa, 300°C is expanded through a steady-flow, adiabatic turbine to 30 kPa. How much work does this turbine produce? |
| | A) | 478.7 kJ/kg |
| | B) | 523.2 kJ/kg |
| | C) | 639.2 kJ/kg |
| | D) | 741.6 kJ/kg |
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| 4 | |
Which temperature-specific entropy state diagram below correctly represents the isobaric cooling process occurring in a heat exchanger?
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| | A) | a |
| | B) | b |
| | C) | c |
| | D) | d |
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| 5 | |
The total amount of heat added to a closed system executing the reversible, isothermal process shown below is given by:
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| | A) | Qin = T (s2 - s1) |
| | B) | Qin = T (s1 - s2) |
| | C) | Qin = mT (s2 - s1) |
| | D) | Qin = mT (s1 - s2) |
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| 6 | |
According to the Tds equation, the specific entropy change of air when it is heated from T1 to T2 while executing an isobaric process is: |
| | A) | cvln (T2 / T1) |
| | B) | cPln (T2 / T1) |
| | C) | cvln (T2 / T1) - R ln (v2 / v1) |
| | D) | cPln (T2 / T1) - R ln (v2 / v1) |
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| 7 | |
Air at 5 MPa, 967°C is expanded through a steady-flow device to 100 kPa, 27°C. What is the change in the specific entropy of the air? |
| | A) | -1.372 kJ/kg-K |
| | B) | -0.269 kJ/kg-K |
| | C) | 1.742 kJ/kg-K |
| | D) | 2.638 kJ/kg-K |
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| 8 | |
A 0.5-kg steel (C = 0.5 kJ/kg-k) rivet cools from 800 K to 300 K upon being installed in a riveted building structure. The entropy change of this rivet is: |
| | A) | -0.631 kJ/K |
| | B) | -0.245 kJ/K |
| | C) | 0.245kJ/K |
| | D) | 0.631 kJ/K |
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| 9 | |
Oxygen at 100 kPa, 27°C is compressed to 1 MPa in an adiabatic compressor whose isentropic efficiency is 0.80. The oxygen temperature at the compressor outlet is: |
| | A) | 376 K |
| | B) | 421 K |
| | C) | 566 K |
| | D) | 649 K |
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| 10 | |
Water undergoes the reversible process illustrated here as it passes through a steady-flow device that has one outlet and one outlet. How much work does this device produce?
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| | A) | 0 kJ/kg |
| | B) | P (v2 - v1) kJ/kg |
| | C) | R (T2 - T1) kJ/kg |
| | D) | cv (T2 - T1) kJ/kg |
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