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Q6. A volume of 1 m³ of air at a pressure and temperature of 4 bar and 150ºC respectively expands isentropically to 1 bar, after which 120 kJ of heat is added at constant pressure.

The two processes can be replaced with a single polytropic process operating between the same initial and final states.

(a) Sketch the processes on Pressure-Volume and Temperature-specific entropy diagrams.

(b) Calculate EACH of the following:

(i) The original total work done

(ii) The index of expansion for the single polytropic process

(iii) The total change in entropy.

Note: For air C_p= 1.005 kJ/kgK, R = 0.287 kJ/kgK and γ = 1.4