The first steam power plant operates on an ideal reheat Rankine cycle. Steam enters the first turbine at 8 MPa and 500 C and leaves at 3 MPa. Steam is then reheated at a constant pressure to 500 C before it expands to 20 kPa in the low-pressure turbine. Assuming that heat is being added to the boiler from a high temperature source at 1800 K and the condenser is transferring heat to a temperature sink at 300 K. Task 1 1. Draw a TS diagram showing all the states and processes 2. Determine the total work output from the turbines 3. Determine the thermal efficiency of the cycle
The first steam power plant operates on an ideal reheat Rankine cycle. Steam enters the first turbine
at 8 MPa and 500 C and leaves at 3 MPa. Steam is then reheated at a constant pressure to 500 C
before it expands to 20 kPa in the low-pressure turbine. Assuming that heat is being added to the
boiler from a high temperature source at 1800 K and the condenser is transferring heat to a
temperature sink at 300 K.
Task 1
1. Draw a TS diagram showing all the states and processes
2. Determine the total work output from the turbines
3. Determine the thermal efficiency of the cycle
Task 2
4. Investigate the effect of changing turbine efficiency on the overall thermal efficiency of the
thermodynamic cycle. (Hint: You will assume different values for the isentropic turbine
efficiency such as: 70%, 80%, 90%, 95%, and 100%, then observe how it will change the
thermal efficiency of the cycle). Representing the results in a plot is recommended.
5. Investigate the effect of changing pump efficiency on the overall thermal efficiency of the
efficiency such as: 70%, 80%, 90%, 95%, and 100%, then observe how it will change the
thermal efficiency of the cycle). Representing the results in a plot is recommended.
6. Investigate the effect of changing high and low pressures in the cycle described in scenario 1
on the overall performance (i.e., thermal efficiency). (Hint: First you will have to change the
high-pressure value then observe how it will affect the efficiency, then change the low
pressure and observe how the efficiency of the cycle will change).
Task 3
7. Discuss the need for superheated steam in a power generating plant (Provide a T-S diagram
and show the difference in the amount of Wnet in the cycle)
8. What limitations prevent the turbine inlet temperature to be superheated above 650º C?.
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