Applying the Exergy Balance: Closed SystemsAs shown in Fig. P7.29, 1.11 kg of Refrigerant...

Applying the Exergy Balance: Closed Systems

As shown in Fig. P7.29, 1.11 kg of Refrigerant 134a is contained in a rigid, insulated vessel. The refrigerant is initially saturated vapor at −28°C. The vessel is fitted with a paddle wheel from which a mass is suspended. As the mass descends a certain distance, the refrigerant is stirred until it attains a final equilibrium state at a pressure of 1.4 bar. The only significant changes in state are experienced by the refrigerant and the suspended mass. Determine, in kJ,

(a) the change in exergy of the refrigerant.

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(b) the change in exergy of the suspended mass.

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(c) the change in exergy of an isolated system of the vessel and pulley-mass assembly.

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(d) the destruction of exergy within the isolated system.

Let T0 = 293 K(20°C), p0 = 1 bar.

Fig. P7.29