3. Air is to be compressed from a pressure of 1 bar and a temperature of 20C to a pressure of 15 bar in a two stage compressor with intercooling. After intercooling the air temperature returns to 20C and the polytropic index of compression is 1.28. If the input power per stage of compression is 2 kW, calculate:

(a) The volumetric flow rate of free air (at 1 bar and 20C) in m3 s-1 .

(b) The power required if the same compression was carried out in one stage isothermally.

(c) Represent the isothermal and two stage compressions on a p-V diagram, indicating the work done for each process.