In: Mechanical Engineering
An ideal Rankine cycle operates without superheat (wet cycle) as shown in the following T-s diagram. If saturated steam is expanded from 450 psia to steam with 5 % moisture, use the Mollier diagram and steam tables, as necessary, to determine the pump inlet temperature, in oF. State your answer to one decimal place.
Given that saturated steam (state 4) is expanded from 450 psia to steam with 5 % moisture (state 5).
• First mark a point (marked as yellow point in the figure) corresponding to constant pressure 450 psia in the saturation line.
• Draw a horizontal line from yellow point to the enthalpy axis. It gives the turbine inlet enthalpy.
Turbine inlet enthalpy, h4 =1205 Btu/lbm
• Draw a vertical line from that point (yellow) to the entropy axis.
• Now mark a point (marked as red in the figure) corresponding to 5% moisture on that vertical line.
• Draw a horizontal line from red point to the enthalpy axis . It gives the required turbine outlet enthalpy.
Turbine outlet enthalpy, h5 = 1165 Btu/lbm
Pressure at turbine outlet, P5 = 250 psia
From steam tables corresponding to pressure 250 psia,
Temperature, T5= 406.04oF
Pump inlet temperature, T1 = T5 = 406.04oF