A mass of 6 kg of a saturated liquid plus vapor mixture of water exists at 175 k

ID: 1860175 • Letter: A

Question

A mass of 6 kg of a saturated liquid plus vapor mixture of water exists at 175 kPa in a

well-insulated, rigid tank. Initially, the quality is 0:2134. An electric resistance heater is

used to change the quality to 1:0.

(a) What is the electric work of the heater required for this process to occur?

(b) What is the entropy change in the process?

(d) What is the average boundary temperature of the process?

(e) Ignoring that the process is isometric, mathematically determine from the 2nd law of

thermodynamics how much heat would need to be removed in order for the process

to be isentropic given an entropy production of 20 kJ=K and an average boundary

temperature of 150 C?

(f) Can the process in part (e) occur if it is both isentropic and isometric? Explain.

(a) 1742.56 kJ, (b) 7606 kJ, (b) -37.44 kJ

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