 A compressor, in delivering compressed air to power tools, compresses air from an initial
pressure and temperature of P 1 = 120 kPa, and T 1 = 20 o
C, up to a final pressure and
temperature of P 2 = 1.0 MPa, and T 2 = 300 o
C. The volumetric flow rate of air into the
compressor is 0.01 m 3
/sec. Find:

o The mass flow rate of air through the compressor.
o The power drawn by the compressor.
Solution
P*V=mRT
R for air=286.9 J/kgK
T=20=273+20=293K
so m=120*10^3*0.01/(286.9*293)
=0.014 kg/s
for adiabatic gas relation is
T1/P1^(n-1)/n=T2/P2^(n-1)/n

so T1/T2=(P1/P2)^(n-1)/n
so n=1.46
P=mR(T2-T1)/(n-1)=0.014*286.9*(573-293)/(1.46-1)
=2444.88 W