Chapter 10.9, Problem 130FEP

Pressurized feedwater in a steam power plant is to be heated in an ideal open feedwater heater that operates at a pressure of 2 MPa with steam extracted from the turbine. If the enthalpy of the feedwater is 252 kJ/kg and the enthalpy of the extracted steam is 2810 kJ/kg, the mass fraction of steam extracted from the turbine is

1. (a)   10 percent
2. (b)   14 percent
3. (c)   26 percent
4. (d)   36 percent
5. (e)    50 percent