Initial conditions of steam:
From steam table
initial state specific volume (v1)= vf+X(vg-vf)
Now heat is supplied at constant volume such that temperature of system becomes
Temperature T=4000C,specific volume (v2)=(v1)=0.7529 m3/kg
From steam table the critical temperature Tc=373.94
Since T2=400C >Tc, Steam is super heated ,
From superheated steam table at T=400c and v=0.7530m3/kg,
we get following value of P and v at T=400C
therefore pressure (p) at v=0.7539 m3/kg is given by linear interpolation
Temperature T=140C, The specific volume of saturated steam(vg)=0.50845 m3/kg
The specific volume of system(v2)=v1=0.7529 m3/kg is more than that of saturatred steam at 140 C.
therefore steam is superheated .
From superheated steam table at T=140C
herefore pressure (P2) at v=0.7539 m3/kg is given by linear interpolation