The power output produced from the turbine, and the overall isentropic efficiency of turbine.
Answer to Problem 197RP
The power output produced from the turbine is
The overall isentropic efficiency of turbine is
Explanation of Solution
Write the formula to calculate the specific entropy of steam from tables
Here, specific entropy of saturated liquid is
Write the formula to calculate the specific enthalpy of steam from tables
Here, specific entropy of saturated liquid is
Draw the
Write the formula for isentropic efficiency of the turbine
Here, specific enthalpy at the turbine inlet is
Write the formula for isentropic efficiency of the turbine
Here, specific enthalpy at the actual turbine exit is
Write the expression for the energy balance Equation for a closed system.
Here, net energy rate transfer into the control volume is
Write the general expression to calculate the isentropic efficiency of turbine
Here, actual work output is
Conclusion:
The rate of change in energy of the system is zero at steady state.
Substitute
Substitute
Re-write the Equation (VIII) for the isentropic work output
Here, mass flow rate of steam at inlet is
From the Table A-6 “Superheated water”, obtain the specific enthalpy
From the Table A-5 “Saturated water - Pressure”, obtain the following properties of water at pressure of
Substitute
Substitute
Equation (II).
Substitute 0.97 for
Equation (III).
Substitute
Substitute
From the Table A-5 “Saturated water - Pressure”, obtain the following properties of water at pressure of
Substitute
Substitute
Substitute
Substitute
Thus, the power output produced from the turbine is
Substitute
Substitute
Thus, the overall isentropic efficiency of turbine is
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Chapter 7 Solutions
Thermodynamics: An Engineering Approach
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