The boiler in a power plant heats water to a temperature near 600 8 C before it enters the turbine. The water is preheated by mixing it with superheated steam extracted from the turbine before it enters the boiler, resulting in less fuel used by the boiler. The insulated preheater is shown in Fig. 6.57. Determine the entropy production if all pressures are at 600 kPa and
a) m1 = 2 kg/s of steam at 250° C
m2 = 20 kg/s of water at 45° C
b) m1 = 2.4 kg/s of steam at 200° C
m2 = 24 kg/s of water at 40° C
c) m1 = 2.8 kg/s of steam at 180° C
m2 = 30 kg/s of water at 50° C
Figure 6.57

Transcribed Image Text:

Mixture of steam and water