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steve2510
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Homework Statement
The power output of an adiabatic steam turbine is 5 MW. If the device can be assumed
to operate as a steady flow device with isentropic expansion, determine the
following:
i) The dryness fraction, x, at the exit from the turbine;
ii) The work output per unit mass of steam flowing through the device;
Intital state : 20 BAR, 400°C C=50M/S Z=10M
Final State : 16 KPA, c = 180m/s z = 6m
Homework Equations
Q+W+h1+c12/2 + z1g = H2+c22/2 + z2g
The Attempt at a Solution
I looked up the following in steam tables
@20 Bar
Ts= 212.4
vg=0.1511
hg=3248
@16kpa
Ts = 55.3
Hf = 232
hfg= 2369
So if its dry i know that h=hf + xhfg
Im confused is it hasnt given a value of γ so I'm not sure if i am supposed to use the fact that:
(P2/P1)γ-1/γ = T2/T1
If i do use that and take a value of gamma to be 1.4 i get :
(16x10^3/2x10^6)^2/7 = T2/T1 Thefore T2= 169.4 ° K but that's actually below 0°C, so surely this isn't correct. Could anyone point me int he right direction please