What is the ideal work for the compression process of Ex. 7.9? What is the thermodynamic efficiency of the process? What are SG and Wlost? Take Tσ = 293.15 K.
Air at 1(atm) and 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
35°C and the maximum allowable outlet temperature is 200°C. Mechanical power is
the same for all stages, and isentropic efficiency is 65% for each stage. The volumetric
flow rate 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 25°C and leaves at 45°C.
What is the cooling-water rate per intercooler?
Assume air is an ideal gas with CP = (7/2)R.