548 ENGINEERING THERMODYNAMICS
dharm
\M-therm\Th12-1.pm5
Condenser pressure
Efficiency
(c)
Fig. 12.5. Effect of operating conditions on the thermal efficiency of the Rankine cycle.
The thermal efficiency of the Rankine cycle is also improved by the following methods :
(i)By regenerative feed heating.
(ii)By reheating of steam.
(iii)By water extraction.
(iv)By using binary-vapour.
+Example 12.1. The following data refer to a simple steam power plant :
S. No. Location Pressure Quality/temp. Velocity
- Inlet to turbine 6 MPa (= 60 bar) 380°C —
- Exit from turbine 10 kPa (= 0.1 bar) 0.9 200 m/s
inlet to condenser
- Exit from condenser 9 kPa (= 0.09 bar) Saturated —
and inlet to pump liquid
- Exit from pump and 7 MPa (= 70 bar) — —
inlet to boiler
- Exit from boiler 6.5 MPa (= 65 bar) 400°C —
Rate of steam flow = 10000 kg/h.
Calculate :
(i)Power output of the turbine.
(ii)Heat transfer per hour in the boiler and condenser separately.
(iii)Mass of cooling water circulated per hour in the condenser. Choose the inlet tempera-
ture of cooling water 20°C and 30°C at exit from the condenser.
(iv)Diameter of the pipe connecting turbine with condenser.
Solution. Refer Fig. 12.6.
(i)Power output of the turbine, P :
At 60 bar, 380°C : From steam tables,
h 1 = 3043.0 (at 350°C) +
3177 2 3043 0
400 350
..−
bg− × 30 ... By interpolation
= 3123.5 kJ/kg
