Answer to Question #253006 in Mechanical Engineering for lorenz

Question

A reheat-regenerative engine receives steam at 207 bar and 59.3 °C, expanding it to 38.6 bar, 343°C. At this point the steam passes through a reheater and reenters the turbine at 34.5 bar. 593°C, hence expands to 9 bar, 492°C, at which point the steam is bled for feedwater heating. Exhaust occurs at 0.07 bar. Beginning at the throttle (point 1) enthalpies are known (in kJ/kg). 

Answer 1

For an ideal engine, for one kg of throttle steam,find the mass of bled steam.

From the steam tables;

At P=207 bar , T=59.3°C

h₁=5810kJ/kg, s₁=6.40kJ/kg

s₁=s₂, h₂=2980kJ/kg

h₃=3663.9kJ/kg, s₃=7.31kJ/kg

By energy balance,

mh₃+(1-m)h₂=h₃

m*3663.9+(1-m)*2980=3663.5

Calculate to get:

683.9m=683.5

m=0.99942kg