Discussion (cont.)

• If we assume the system is operated under a Carnot cycle, then h=1-TL/TH, where TL=45.8°C, TH=275.6 °C, both from table A-5. (How?). Therefore, h=0.418. The Rankine efficiency should be less than that.

• Increase pressure to 0.1 MPa, the condensing temperature increases to 99.6 °C. Therefore, the efficiency based on Carnot cycle should decrease to 0.321.

• The percentage change is (0.418-0.321)/0.418=23.2%, a significant drop in thermal efficiency.

• However, the real change of the thermal efficiency is very small. Explain why?

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