Question
Question:
A 125 MW power plant operates on a modified Rankine cycle with water as the working fluid. Superheated steam enters the turbine (State 3) at a pressure of 15 MPa and a temperature of 650 degree C. Subcooled water leaves the condenser (State 1) at a pressure of 30 kPa and a temperature of 60 degree C. The turbine is adiabatic but not reversible and has an isentropic efficiency of 88 %, The pump is adiabatic and internally reversible, The heat transfer in both the condenser and the boiler take place at constant pressure. Complete the table below. Sketch the cycle on a T-s diagram. Use a dashed line to show isentropic processes and a solid line to show actual processes. Label all points and processes. Find: The net work output of the cycle, in kJ/kg. The percent error in the net work if the work of the pump is neglected, The mass flow rate of the water, in kg/hr and The thermal efficiency of the cycle.
Explanation / Answer
state1
v1=0.001022m^3/kg
h1=289.3kj/kg
s1=.944kj/kg-k
state2
v2=0.001658
h2=1610.9
s2=3.689
state3
v3=0.026735
h=3707.6
s=6.815
state4
v4=5.2293
h4=2625.4
s4=7.769
STEP;
a)net work output=(h3-h4)-(h2-h1)
b)%error=(h3-h4)/((h3-h4(-(h2-h1))*100
c)mass flow rate=125000/(net work output)
effeciency=net work output/(h3-h2)