Air at 1 atm and 308.15 K (35°C) is compressed in a staged reciprocating compressor (with intercooling) to a final pressure of 50 atm. For each stage, the inlet gas temperature is 308.15 K (35°C) and the maximum allowable outlet temperature is 473.15 K (200°C). Mechanical power is the same for all stages, and isentropic efficiency is 65% for each stage. The volumetric flowrate of air is 0.5 m3 s-1 at the inlet to the first stage.
(a) How many stages are required?
(b) What is the mechanical-power requirement per stage?
(c) What is the heat duty for each intercooler?
(d) Water is the coolant for the intercoolers. It enters at 298.15 K (25°C) and leaves at 318.15 K (45°C). What is the cooling-water rate per intercooler?
Assume air is an ideal gas with Cp = (7/2)R.