Question

a) Explain the methods that can be adopted to increase the thermal efficiency of a vapor power cycle. You may use a T-s diagram to explain your reasons. b) A steam regenerative cycle, shown below, is delivering 100 MW of power. Steam from the boiler is supplied to the turbine at 8 MPa, 400°C. After expanding isentropically in the 1st stage turbine to a pressure of 1 MPa, steam is taken to the reheater where its temperature is raised back to 400°C and supplied to the 2nd stage turbine. Expansion in the 2nd stage turbine is also isentropic to a pressure of 400 kPa, where a fraction (y = 10%) of the steam is extracted and fed to the closed FWH as shown. Remaining steam continues to expand isentropically to the condenser pressure of 50 kPa. Steam is saturated liquid at the exit of the condenser. The extracted steam is also saturated liquid at the exit of the FWH. Assume work of both pumps are negligible (i.e., Wpump I = 0, Wpump II = 0). Assume there is no pressure drop in the system. Do the following: i) Draw the corresponding T- s diagram. Your plot must represent correct state corresponding to the steam at each point. Determine: ii) The required steam mass flow rate, kg/s iii) The amount of heat supplied at the boiler, kJ/s iv) The thermal efficiency of the cycle, %

Answer 1