A steam power plant operates on an ideal reheat regenerative Rankine cycle with one reheater and two feedwater heaters, one open and one closed. Steam enters the high-pressure turbine at 15 MPa and 6008C and the low- pressure turbine at 1 MPa and 5008C. The condenser pressure is 5 kPa. Steam is extracted from the turbine at 0.6 MPa for the closed feedwater heater and at 0.2 MPa for the open feedwater heater. In the closed feedwater heater, the feedwater is heated to the condensation temperature of the extracted steam. The extracted steam leaves the closed feedwater heater as a saturated liquid, which is subsequently throttled to the open feedwater heater. Show the cycle on a T-s diagram with respect to saturation lines. Determine (a) the fraction of steam extracted from the turbine for the open feedwater heater, (b) the thermal efficiency of the cycle, and (c) the net power output for a mass flow rate of 42 kg/s through the boiler

ME 3350 Notes – Week 6 7 – Energy Equation Stored Energy: Associated with given mass (kinetic→motion, potential→position, internal) Energy in transition: Moving between systems (heat→temperature difference, work→external forces) Consider a system: Work done by fluid on surroundings, heat to system from surroundings dE ∆ E=E −2 =Q1W =Q−W ´ RTT: dt δ ρedV + ρev∙dA=Q−W ´ ´ δt CV CS Physical Interpretation: Time rate of change (RoC) of stored energy in CV @ t + Net efflux of stored energy through CS @ t = Rate of heat addition to fluid in CV @ t – Rate of work done by fluid in CV @ t, 1 2