Question 11.CSGP.61: A steam power plant operates with with a high pressure of 5 ......
A steam power plant operates with with a high pressure of 5 MPa and has a boiler exit temperature of of 600°C receiving heat from a 700°C source. The ambient at 20°C provides cooling for the condenser so it can maintain 45°C inside. All the components are ideal except for the turbine which has an exit state with a quality of 97%. Find the work and heat transfer in all components per kg water and the turbine isentropic efficiency. Find the rate of entropy generation per kg water in the boiler/heat source setup.
Take CV around each component steady state in standard Rankine Cycle.
1: v = 0.00101; h = 188.42, s = 0.6386 (saturated liquid at 45°C).
3: h = 3666.5 kJ/kg, s = 7.2588 kJ/kg K superheated vapor
CV Turbine: no heat transfer q = 0
w _{ ac }= h _3- h _{4 ac }=3666.5-2511.4= 1 1 5 5 . 1 ~ k J / k g
Ideal turbine: s _4= s _3=7.2588 \Rightarrow x _{4 s }=0.88, \quad h _{4 s }=2295\, kJ / kg
CV Condenser: no shaft work w = 0
q _{\text {out }}= h _{4 ac }- h _1=2511.4-188.42= 2 3 2 3 ~ k J / k g
CV Pump: no heat transfer, q = 0 incompressible flow so v = constant
w = v \left( P _2- P _1\right)=0.00101(5000-9.59)= 5 . 0 4 ~ k J / k g
CV Boiler: no shaft work, w = 0
s _{\text {gen }}=7.2588-0.6386-\frac{3473}{700+273}= 3 . 0 5 ~ k J / k g ~ K