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Direction: The inlet and the outlet conditions of steam for an adiabatic steam turbine are as indicated in the notations are as usually followed.

  1. If mass flow rate of steam through the turbine is 20 kg/s, the power output of the turbine (in MW) is
    1. 12.157
    2. 12.941
    3. 168.001
    4. 168.785
Correct Option: A

SFEE h1 + z1g +
1
+ Q = h2 + z2g +
2
+ W
22

For adiabatic process, Q = 0
∴ h2 + z1g +
1
= h2 + z2g +
2
+ W
22

Or 3200 × 10³ + 10 × 9.81 +
160 × 160
2

= 2600 × 10³ + 6 × 9.81 +
100 × 100
+ W
2

⇒ W = 600 × 10³ + 39.24 +
2600 - 1000
+ W
2

= 607839.24 × 20 J/s = 12.156 MW

Applying S.F.E.E
w1h1 +
1
+ gz1 +
dQ
w2h2 +
2
+ gz2 +
δw
22

Here, w1 = mass flow rate
dQ
= 0 for insulated turbine

∴ 203200 +
160²
× 9.81 × 10
2 × 10³

= 202600 +
160²
+
9.81 × 6
+
dw
2 × 10³10³

Or
dw
= 20(3200 - 2600) +
1
160²
-
100²
+
9.81(10 - 6)
10³2210³

= 20 × {600 + 7.8 + 0.03924}
= 20 × 607.83924 kW
= 12156.7848 kW ≃ 12.157MW



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