Air is to be compressed from 120 kPa and 310 K to 700 kPa and 430 K. A heat loss of 20 kj/kg occurs during the compression process. For air: cv=0.7165 kj/kg.K and R=0.287 kj/kg.K .
A) Neglecting kinetic energy changes determine the power input required for a mass flow rate of 90 kg/min.
The Attempt at a Solution
m = 90 kg/min = 1.5kg/s
Apply 1st law of thermodynamics - energy conservation
Ein = Eout
Win + Mh1 = Qout + mh2
Win + mCpT1 = Qout + mCpT2
Cp = 1.005 Kj/Kg.K
Win + 1.5kg X 1.005 KJ/Kg.K X 310K = 20KJ/Kg/K + 1.5Kg/s X 1.005 KJ/Kg.K X 430K=
Win = 201Kw.
Is this correct?