Steam enters a two-stage adiabatic turbine at 8 MPa and 550ºC (State 1) and is expanded to 2 MPa (State 2) in the first stage of expansion. This steam is reheated at constant pressure to 550ºC (State 3) before entering the second stage of expansion. Steam leaves the second turbine stage at 150 kPa (State 4). The power output of the two-stage turbine is 80 MW and isentropic efficiency of each turbine stage is 84%.
a) Calculate the mass flow rate (kg/s) through the two-stage turbine.
b) Determine the temperature (ºC) at the exit of each turbine.
c) Calculate the rate of entropy generation (kW/K) for the two-stage turbine.
d) Show the two-stage expansion process on T-s diagram. Label states, show property values, and indicate appropriate lines of constant pressure.