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Q8. A two-stage single acting reciprocating air compressor is designed for minimum work and perfect intercooling. The inlet pressure and temperature are 0.9 bar and 25℃ respectively, the delivery pressure is 32.4 bar.

The free air capacity of the compressor is 8.5 m³/min at a speed of 360 rev/min and a pressure and temperature of 1.013 bar and 0℃ respectively. The clearance ratio of each stage is 0.05 and polytropic index for all compression and expansion processes is 1.28.

(a) Sketch the cycle on a Pressure -Volume diagram indicating the work saved by intercooling. (3)

(b) Calculate EACH of the following:

(i) The total volume of the low-pressure cylinder; (5)

(ii) The indicated power of the machine; (3)

(iii) The power saved by intercooling.(5)