HW07_solns[1]

HW07_solns[1] - refrigerant-134a vapor.” The problem on...

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San Francisco State University ENGR 303: Engineering Thermodynamics School of Engineering Prof. Ed Cheng, Spring 2011 Homework 7 solutions NOTE : Solutions for HW problems that are based upon textbook problems reflect numerical values from the text. Numerical values may differ for these problems when they appear on iLearn. In such cases, the solution presented below provides the appropriate solution method . 1. The correct choice is (c): zero or positive. 2. For an irreversible process, Sgen must be positive. Therefore, the entropy change of the system can only be zero if entropy is transferred out of the system. This can only occur if heat is transferred out of the system (entropy transfer accompanies heat transfer). The correct choice is (c).
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San Francisco State University ENGR 303: Engineering Thermodynamics School of Engineering Prof. Ed Cheng, Spring 2011 HW 7 solutions 2 3: The problem statement should have stated “3 kg of saturated
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Unformatted text preview: refrigerant-134a vapor.” The problem on iLearn differs from that solved below in that the mass was directly given (rather than the volume, which is used in the below solution to calculate the mass using the specific volume). San Francisco State University ENGR 303: Engineering Thermodynamics School of Engineering Prof. Ed Cheng, Spring 2011 HW 7 solutions 3 4 Properties The gas constant of air is R = 0.287 kJ/kg-K (Table A-1). The specific heat ratio of air is k = 1.4 and C v = 0.718 (at 300K). (0.718 kJ/kg-K)(525.3 – 290)K = 168.9 kJ/kg San Francisco State University ENGR 303: Engineering Thermodynamics School of Engineering Prof. Ed Cheng, Spring 2011 HW 7 solutions 4 5: San Francisco State University ENGR 303: Engineering Thermodynamics School of Engineering Prof. Ed Cheng, Spring 2011 HW 7 solutions 5 6:...
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HW07_solns[1] - refrigerant-134a vapor.” The problem on...

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