uperheated steam generated in a power plant at a pressure of 8,600 kPa and a temperature of 500 ℃ is fed to a turbine. Exhaust from the turbine enters a condenser at 15 kPa, where it is condensed to saturated liquid, which is then pumped to the boiler. (a) What is the thermal efficiency of a Rankine cycle operating at these conditions? (b) What is the thermal efficiency of a practical cycle operating at these conditions if the turbine efficiency and pump efficiency are both 75%?
Superheated steam generated in a power plant at a pressure of 8,600 kPa and
a temperature of 500 ℃ is fed to a turbine. Exhaust from the turbine enters a
condenser at 15 kPa, where it is condensed to saturated liquid, which is then
pumped to the boiler.
(a) What is the thermal efficiency of a Rankine cycle operating at these
conditions?
(b) What is the thermal efficiency of a practical cycle operating at these
conditions if the turbine efficiency and pump efficiency are both 75%?
Which of the two efficiencies has greater impact on the thermal efficiency?
(c) Sketch both cycles in the same T-s diagram.
(d)If the power output of the turbine is 80,000 kW in case (b), calculate the
mass flow rate of the working fluid.
(e) Calculate the heat transfer rates in the boiler and the condenser. Double
check the result for the condenser.
(f) For both cases (a) and (b), make a comment about the operation of turbine
(issue of cavitation). [one sentence is fine]
(g) How you would operate the condenser of a practical cycle (issue of
cavitation in the pump)? [one sentence is fine].
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