A multistage compressor has to be designed to supply air at 135 bar, while atmospheric condition is 1.03 bar and 15° C. The value of compression index may be assumed as 1.35. Due to practical reasons the intercoolers are not able to cool the air below 45° C, while the maximum temperature allowable in the system is 120° C. Calculate the number of stages that are necessary in the compression and the rate of cooling water circulated per kg of air
(Cp = 1 kJ/kg C).