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Q3. In a two-stage, single acting reciprocating air compressor, the LP suction pressure is 1.05 bar, the inter-stage pressure is 3.15 bar and the HP delivery pressure is 10.2 bar. The LP suction temperature is 298 K and the HP suction temperature is 311 K. The index of compression and expansion for both stages is 1.29.

(a) Sketch the process on a p-V diagram indicating the areas which represent work saved by intercooling and the isothermal curve.

(b) Calculate EACH of the following per kg of induced air:

(i) The indicated work

(ii) The heat removed in the intercooler

(iii) The work saved by intercooling.

(c) Calculate the isothermal efficiencies with and without intercooling.

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