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Q11. The free air capacity of a reciprocating air compressor is 20 m³/min. Free air and suction pressure and temperature are respectively 1.1 bar and 31°C. The delivery pressure is 6.875 bar. Compression is carried out in two stages with perfect intercooling. The stage pressure ratios are equal. The index of compression and expansion is 1.30.

(a) Sketch the p-V diagram for the compressor.

(b) Calculate EACH of the following:

(i) The total indicated power

(ii) The rate of intercooling

(iii) The power saved by intercooling.

Note: For air, R = 0.287 kJ/kg K and C_p = 1.005 kJ/kg K.