Superheated steam enters a turbine (10 MPa, 480 C) of an ideal Rankine cycle with reheat and exits at 6 kPa. Steam expands through the first-stage turbine to 0.7 MPa and then is reheated to 480 C. Express all answers with 3 significant digits. Without using special software (Excel and calculators are acceptable), perform the following tasks:

1. Calculate the total heat addition, net work of the cycle, heat extraction through condenser, and thermal efficiency of this ideal Rankine cycle with reheat. [20]

2. From scratch, calculate the same quantities assuming that the pump and each turbine stage have an isentropic efficiency of 80%. [20]

3. Draw the T-s diagrams for both cycles on the same plot. [20]

4. Draw the p-v diagrams for both cycles on the same plot. [19]

5. For a pressure of 7 bar right after the first stage turbine in the ideal Rankine cycle, create two plots: thermal efficiency as a function of the reheat temperature from 200 C to 500 C; and the net work, heat addition, and heat extraction on the same graph as a function of the reheat temperature from 200 C to 500 C. [14]

6. Is there a local maximum or minimum thermal efficiency for 200 C < Treheat < 500 C? Explain why or why not? If so, what is it, at what reheat temperature does it occur, and how does one determine such an efficiency? [4]

7. What did you learn from this exercise? [1]

Just numbers 5 and 6 please