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Q8. A four stage reciprocating air compressor is designed for minimum work and has perfect intercooling. The inlet pressure and temperature are 0.958 bar and 17℃ respectively.

The discharge pressure is 245.28 bar.

The index of expansion and compression in all stages is 1.22.

The air delivery is 2 m³/s at free air conditions of 1.015 bar and 15℃.

The mechanical efficiency of the compressor is 82 %.

(a) Calculate EACH of the following.

(i) The inter stage pressures; (3)

(ii) The air delivery temperature; (2)

(iii) The power input; (4)

(iv) The total heat removed by the inter coolers. (4)

(b) Sketch the cycle on a pressure-Volume diagram indicating the intermediate pressures (3)

Note: For air R = 287 J⁄(kg K), γ = 1.4.