Question 9.CSGP.134: Find the isentropic efficiency for the compressor in Problem......
Find the isentropic efficiency for the compressor in Problem 6.57.
A compressor in an air-conditioner receives saturated vapor R-410a at 400 kPa and brings it to 1.8 MPa, 60°C in an adiabatic compression. Find the flow rate for a compressor work of 2 kW?
C.V. Actual Compressor, assume adiabatic and neglect kinetic energies.
Energy Eq.6.13: w = h _1- h _2
Entropy Eq.9.9: s _2= s _1+ s _{ gen }
States: 1: B.4.2 h _1=271.9\, kJ / kg , \quad s _1=1.0779 \,kJ / kg – K
2: B.4.2 h _2=323.92 \,kJ / kg
– w _{ C }= h _2- h _1=323.92-271.9=52.02 \,kJ / kg
Ideal compressor. We find the exit state from (P,s).
State 2s: P _2, s _{2 s }= s _1=1.0779 \,kJ / kg – K \Rightarrow h _{2 s }=314.33 \,kJ / kg
– w _{ Cs }= h _{2 s }- h _1=314.33-271.9=42.43\,kJ / kg
\eta_{ C }=- w _{ C s } /- w _{ C }=\frac{42.43}{52.02}= 0 . 8 1 6