Question

A steam turbine has inlet steam pressure p_{1} = 1.4 MPa
absolute. Inlet steam temperature is T_{1} = 400
^{o}C. This corresponds to inlet enthalpy per unit mass of
h1 = 3121 kJ/kg. Exit pressure of the steam is p_{2} = 101
kPa absolute. Exit steam temperature is T_{2} = 100
^{o}C. This corresponds to exit enthalpy per unit mass of
h_{2} = 2676 kJ/kg. Inlet speed of the steam is
V_{1} = 15 m/s and exit speed is V_{2} = 60 m/s.
Axis of the steam turbine is horizontal. Time-rate of heat loss
through the walls of the turbine is Q = 7600 kJ/h. The mass flow
rate of steam through the turbine is 0.5 kg/s.

a) If the power extracted by the turbine is P_{actual} =
200 kW, what is the amount of power loss (expressed in kW) due to
viscous effects?

b) If there would be no viscous losses, what would be the ideal
power, P_{ideal}, extracted by the turbine (in kW)?

c) What is the coefficient of efficiency, ?, of the turbine?

Answer #1

Increasing the temperature of the heat addition (T subscript
H) in any heat engine cycle, with keeping all other parameters
unchanged:
A.
None of the answers.
B.
Decreases the heat added at high temperature.
C.
Increases the thermal efficiency of the cycle.
D.
Decreases the thermal efficiency of the cycle.
1 points
QUESTION 2
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