Answer:
h1 = 290.16kj/kg
P = 1.2311
Prandil expression at 8
P=p1/p7×pr
=8(1.2311)
=9.85
Enthalpy state at 8 corresponding to 9.85
h1 = 526.13kj/kg
Now prandtl state at 9 that correspond to 1400k.
h9 = 1515.42kj/kg
Pr = 450.5
Prandtl expression at state 10
P= p10/p9×pr
=1/8(450.5)
=56.31
Enthalpy at state 10 corresponding to prandtl 56.31
h10 = 860.39kj/kg
At 520k
h11 = 523.63kj/kg