Page 79 - Handbook of Energy Engineering Calculations

exhaust if in the actual turbine combined efficiency is 72 percent, generator
efficiency is 94 percent, and actual extraction is the same as the ideal.

Calculation Procedure:

1. Assemble the key enthalpies, entropies, and pressures for the cycle
Using the steam tables and a Mollier chart, list the following pressures,

temperatures, enthalpies, and entropies for the cycle, Fig. 13a: P = 600 lb/in 2
t
2
(abs) (4134 kPa); t = 740°F (393°C); P = 100 lb/in (abs) (689 kPa); t =
3
1
2
2
2
700°F (371°C); P = 30 lb/in (abs) (207 kPa); p = 1 lb/in (abs) (6.89 kPa);
x
c
H = 1372 Btu/lb (3197 kJ/kg); S = entropy = 1.605; H = 1188 Btu/lb (2768
1
1
2
kJ/kg); H = 1377 Btu/lb (3208 kJ/kg); S = 1.802; H = 1245 Btu/lb (2901
x
3
3
kJ/kg); H = 1007 Btu/lb (2346 kJ/kg); H = 70 Btu/lb (163 kJ/kg); H = 219
fx
c
f
Btu/lb (510 kJ/kg). Plot Fig. 13b as a skeleton Mollier chart to show the cycle
processes.