Text Exercise 2

Pagina 1

Rankine power cycle Part 1 – Analysis of the real cycle The maximum and minimum operating pressures of a real Rankine power cycle are equal to pmin = 0.2 bar and pmax = 150 bar. The maximum temperature of the cycle is 600°C and the net power is 600 MW and the isentropic efficiency of the steam turbine is taken as 0.9. Assuming that methane combustion is providing the input thermal power to the Rankine cycle, calculate: • the energy exchanges of each single transformation of the cycle • first law and second law efficiencies • the water vapor and fuel mass flow rate, assuming LHVCH4 = 50 MJ/kg • the exergy flows assuming ambient temperature T0 = 300 K Part 2 – Partial load of the real cycle (for individual study, results provided) Repeat all the calculations for the real cycle at 50% load, assuming that the turbine efficiency is reduced by 5%.