Full exam for Energy Systems LM in the Mechanical Engineering degree programme at Politecnico di Milano. The document covers: PROBLEM 1: Data Ambient temperature, °C 15 net GT efficiency 0.35 Net GT electric power, kW 30000 mass flow rate of GT flue gases, kg/s 97 GT exhaust temperature, °C 540 Cp of flue gases, kJ/kgK 1.09 steam mass flow rate of HRSG,kg/s 10 Steam temperature at turbine inlet, °C 525
Full exam for Energy Systems LM in the Mechanical Engineering degree programme at Politecnico di Milano. The document covers: PROBLEM 1: Data Ambient temperature, °C 15 net GT efficiency 0.35 Net GT electric power, kW 30000 mass flow rate of GT flue gases, kg/s 97 GT exhaust temperature, °C 540 Cp of flue gases, kJ/kgK 1.09 steam mass flow rate of HRSG,kg/s 10 Steam temperature at turbine inlet, °C 525
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PROBLEM 1: Data Ambient temperature, °C 15 net GT efficiency 0.35 Net GT electric power, kW 30000 mass flow rate of GT flue gases, kg/s 97 GT exhaust temperature, °C 540 Cp of flue gases, kJ/kgK 1.09 steam mass flow rate of HRSG,kg/s 10 Steam temperature at turbine inlet, °C 525 pressure of steam at turbine inlet, bar 35 pressure drop of superheater, bar 5 water temperature at economizer outlet, °C 240 water pressure at ECO inlet, bar 45 HRSG heat losses, % of heat of flue gases 0.5 condenser pressure, bar 0.07 isentropic turbine efficiency, % 91 efficiency el-mech steam turbine, % 98 efficiency el-mech pump, % 97 hydraulic efficiency pumo 0.82 Results 2) Fuel input (LHV basis) to combustor 85714 kW net GT power/net GT efficiency mass flow rate of GT exhausts 97.00 kg/s from problem data pressure of water at evaporator inlet 40.00 bar turbine inlet pressure + pressure drop of superheater entalpy of water at evaporator inlet 1037.6 kJ/kg knowing p = 45 bar and T = 240 °C, it is possible to use the equations for subcooled water enthaply of steam at turbine inlet 3508.2 kJ/kg knowing p =35 bar and T = 525 °C, it is possible to use the Mollier diagram evaporation temperature 250.4 °C knowjng p = 40 bar, it is possible to use the saturated water property tables DTpinch point 54.80 °C from the energy balance of the HRSG from the hot side to the EVA inlet: mgas*cpgas*(Tgas-Teva-DTpp)*(1-heat_losses) = msteam*(h_in_turbine - h_exit_ECO) stack temperature 223 °C from the energy balance of the overall HRSG: mgas*cpgas*(Tgas-Tstack)*(1-heat_losses) = msteam*(h_in_turbine - hout_pump) 3) turbine inlet entropy 7.23 kJ/kg/K from the mollier diagram knowing p and T isentropic turbine outlet enthalpy 2246.07 kJ/kg from the mollier diagram following the isentropic expansion till pcond…
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