1. Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of 45 MW. Steam enters the turbine at 7 MPa and 500°C and is cooled in the condenser at a pressure of 10 kPa by running cooling water from a lake through the tubes of the condenser at a rate of 2000 kg/s. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the thermal efficiency of the cycle, (b) the mass flow rate of the steam, and (c) the temperature rise of the cooling water. Answers: (a) 38.9 percent, (b) 36 kg/s, (c) 8.4°C
1. Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of
45 MW. Steam enters the turbine at 7 MPa and 500°C and is
cooled in the condenser at a pressure of 10 kPa by running
cooling water from a lake through the tubes of the condenser
at a rate of 2000 kg/s. Show the cycle on a T-s diagram with
respect to saturation lines, and determine (a) the thermal efficiency of the cycle, (b) the mass flow rate of the steam, and
(c) the temperature rise of the cooling water.
Answers:
(a) 38.9 percent, (b) 36 kg/s, (c) 8.4°C
2. Consider a 210-MW steam power plant that operates
on a simple ideal Rankine cycle. Steam enters the turbine at
10 MPa and 500°C and is cooled in the condenser at a pressure of 10 kPa. Show the cycle on a T-s diagram with respect
to saturation lines, and determine (a) the quality of the steam
at the turbine exit, (b) the thermal efficiency of the cycle,
and (c) the mass flow rate of the steam.
Answers: (a) 0.793,
(b) 40.2 percent, (c) 165 kg/s
3. Is it possible to maintain a pressure of 10 kPa in a condenser that is being cooled by river water entering at 20°C?
4. Consider a steam power plant operating on the simple ideal Rankine cycle. Steam enters the turbine at 3 MPa and 350°C and is condensed in the condenser at a pressure of 75 kPa. Determine the thermal efficiency of this cycle.
5. A steam power plant operates on a simple ideal Rankine cycle between the pressure limits of 3 MPa and 50 kPa. The temperature of the steam at the turbine inlet is 300°C, and the mass flow rate of steam through the cycle is 35 kg/s. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the thermal efficiency of the cycle and (b) the net power output of the power plant.
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