1- Determine the efficiency of a Rankine cycle using steam as the working fluid in which the condenser pressure is 10 kPa. The boiler pressure is 2 MPa. The steam leaves the boiler as saturated vapour. (? = 30.3 %)
2- In Rankine cycle steam leaves the boiler and enters the turbine at 4 MPa, 400 °C. The condenser pressure is 10 kPa. Determine the cycle efficiency. (? = 35.3 %)
3- A steam power plant operates on a Rankine cycle. The steam leaves the boiler at 4 MPa and 400 °C. The condenser pressure is 10 kPa. The efficiency of the turbine is 86%. Determine the thermal efficiency of the cycle.
4- Consider a reheat cycle utilizing steam. Steam leaves the boiler and enters the turbine at 4 MPa, 400 °C. After expansion in the turbine to 400 kPa, the steam is reheated to 400 °C and then expanded in the low pressure turbine to 10 kPa. Determine the cycle efficiency. (? = 35.9 %)
5- Consider a regenerative cycle using steam as working fluid. Steam leaves the boiler and enters the turbine at 4 MPa, 400 °C. After expansion to 400 kPa, some of the steam is extracted from the turbine for the purpose of heating the feedwater in an open feedwater heater. The pressure in the feedwater heater is 400 kPa and the water leaving it is saturated liquid at 400 kPa. The steam not extracted expands to 10 kPa. Determine the cycle efficiency. (? = 37.5 %)
6- Consider a simple steam power plant with water mass flow rate of 109 kg/s. Steam enters the turbine at 520 °C, 100 bars and leaves at 0.08 bar, 90 % quality. Steam leaves the condenser as saturated liquid at 0.08 bar. Cooling water from cooling tower enters the condenser at 20 °C and leaves at 35 °C. Determine the plant thermal efficiency and the mass flow rate of the cooling water passing through the condenser.
7- Steam is the working fluid in power plant follows an ideal Rankine cycle. Saturated vapor enters the turbine at 8.0 MPa and saturated liquid exits from the condenser at a pressure of 0.008 MPa. The net power output of the cycle is 100 MW. Determine: the cycle thermal efficiency, the mass flow rate of the steam, the rate of heat transfer in the steam generator, the rate of heat transfer, from the condensing steam in the condenser, the mass flow rate of the condenser cooling water from the cooling tower, if cooling water enters the condenser at 15 °C and exits at 35 °C.
(37.1%, 3.77 *105 kg/h, 269.77 MW, 169.75 MW, 7.3 *106 kg/h)
