A constant-pressure vessel initially contains 7.5 kg saturated steam at P = 0.2 MPa. Heat is removed until the vessel contents have a quality of q = 0.8. The heat removed is transferred to a heat reservoir at a constant T = 373.15 K. Determine the change in entropy of the heat reservoir.
A. 8.40 kJ/K
B. 8.85 kJ/K
C. 8.31 kJ/K
D. -8.31 kJ/K
E. Insufficient information to solve
A. Incorrect. The definition of entropy must be applied at the boundary temperature for the system which is gaining entropy. This is given in the problem statement.
B. Correct. Use the energy balance and then the definition of entropy.
C. Incorrect. You cannot assume constant volume; therefore there may be WEC involved.
D. Incorrect. The heat is negative while leaving the system, but positive while entering the reservoir. Also there is a mistake in your energy balance simplification.
E. Incorrect. There is enough information here to solve the problem.
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