A vessel of capacity 3 m3 contains air at a pressure of 2 bar and temperature

Question

300K. Additional air is pumped into the system until the pressure rises to 30 bar and temperature to 330 K. Determine (a) the mass of air pumped (b) heat transferred , and (c) the change in entropy if the air is cooled down to 300 K . Take Cv = 0.718 KJ/kgK.

Answer 1

V1 =  3 m3

P1 = 2 bar

T1 = 300K

V2 =??

P2 = 30 bar

T2 = 330 K

using ideal gas law

P1*V1 /T1 = P2*V2 /T2

V2 = 0.22 M3

PLEASE note this means that air is pumped out of the vessel, not into it.

VOlume of air pumped out = 3 - 0.22 = 2.78 m3

Density of air at 330 K * volume will give the mass of air pumped out

Heat trasferred = m *Cv * del T

Same for change in entropy

Answer 2

OMG, your such a nerd!