(Solved): Problem 1: Exergy analysis of a heat exchanger In a counterflow heat exchange ...

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Problem 1: Exergy analysis of a heat exchanger In a counterflow heat exchanger $$\mathrm{R}134\mathrm{a}$$ flowa in (State 1 ) at a temperature of $$?20^{?}\mathrm{C}$$, saturated with a vapour quality of $$35\%$$, and flows out (State 2) as saturated vapour at $$?20^{?}\mathrm{C}$$. This stream exchange heat with air flowing in (State 3 ) at a temperature of $$300\mathrm{K}$$ and out (State 4) at $$260\mathrm{K}$$. The air stream has a constant pressure of 2 bar and a mass flow rate of $$4\mathrm{kg}/\mathrm{s}$$. Heat exchange with the surroundings can be neglected, and also changes in kinetic and potential energy. The flows are steady (unchanged with time). The surroundings has state $$T_0=300\mathrm{K}$$ and $$p_0=1$$ bar a) Sketch $$T?s$$ diagrams for the two streams. Include lines for $$T_0$$ and $$p_0$$ in the sketch. b) Determine the rate of exergy destruction $$(\mathrm{kW})$$ in the heat exchanger. c) Express and calculate an exergy efficiency of the heat exchanger. What about energy efficiency?