Conclu

Termodinámica Aplicada Sem 2013-I
Ciclos de vapor
Fecha de entrega: 8 de octubre.
In all these problems use the International Steam Tables and draw the T-s diagram and the
squematic diagram ofthe cycle.
1. A smaller power plant produces steam at 18 MPa, 600 C in the boiler. It keeps the
condenser at 43 C by transfer of 18 MW out as heat transfer. Find the optimal pressure
at which thesteam should be reheated, consider that the moisture content of the steam
at the exit of the low–
pressure turbine is 9% and the same maximum temperature in
the two stages. For this cycle …nd thetotal turbine power output, the boiler heat
transfer, the e¢ ciency and the mass ‡
ow.
2. Consider the Problem 1 assuming an isentropic e¢ ciency of 86 percent for the pump,
and an isentropic e¢ciency of 89 percent for the turbine. Calculate the same data.
3. A steam power plant has high and low pressures of 20 MPa and 10 kPa, and one open
feedwater heater operating at 1 MPa with the exit assaturated liquid. The maximum
temperature is 700 C and the turbine has a total power output of 5 MW. Find the
fraction of the ‡ for extraction to the feedwater and the total condenser heat transferow
rate.
4. Consider the Problem 3 assuming an isentropic e¢ ciency of 85 percent for the pump,
and an isentropic e¢ ciency of 90 percent for the turbine. Calculate the same data,
5. Steam leaves apower plant steam generator at 3.5 MPa, 400 C, and enters the turbine
at 3.4 MPa, 375 C. The isentropic turbine e¢ ciency is 88%, and the turbine exhaust
pressure is 10 kPa. Condensate leaves thecondenser and enters the pump at 35 C, 10
kPa. The isentropic pump e¢ ciency is 80%, and the discharge pressure is 3.7 MPa.
The feedwater enters the steam generator at 3.6 MPa, 30 C. Calculate thethermal
e¢ ciency of the cycle and the entropy generation for the process in the line between
the steam generator exit and the turbine inlet, assuming an ambient temperature of
25 C.
6. A steam...