Consider the following combined cycle. The mass flow rate of airis 73 kg/s. Air enters the compressor at state 1 with Patm =1 atmand Tamb = 20°C. The compressor has a pressure ratio of 7.5 and anefficiency ?c = 0.85. Air enters the combustor and is heated to atemperature TH = 1250°C. The turbine has an efficiency of ?t,1 =0.87. The air leaving the turbine enters the steam boiler where ittransfers heat to the water in the Rankine cycle. The ratio of themass flow rate of water in the Rankine cycle to air in the Braytoncycle is 0.1. The water leaving the boiler achieves temperature of550°C. After boiling the water in the Rankine cycle, the remainingheat left in the Brayton cycle will be used to produce steam forindustrial processes. The air enters the steam generator afterleaving the boiler and is used to heat water from the inlet stateof 5 atm, 20°C to saturated vapor. The temperature of the airleaving the steam generator is 180°C. In the Rankine cycle, thewater enters the pump as saturated liquid at 55°C. The pumpefficiency is ?p = 0.65 and the exit pressure of the pump isPboiler = 8.0 MPa. The water enters the heat exchanger (boiler)where it is converted to steam by the heat transfer from the air.The steam turbine has an efficiency of ?t,2 = 0.84. The condensertransfers heat from the water to a river cooling water entering thecondenser at Tamb = 20°C. Due to EPA regulations the temperature ofthe river water at the exit of the condenser cannot be more than5°C higher than at the inlet.
a.) [20 points] Draw the T-S diagram and the line/componentdiagram for this combined cycle.
b.) [20 points] Determine all of the state points for thiscombined cycle. You may consider creating a table including allrelevant points with at least the pressure, temperature, entropyand enthalpy.
c.) [10 points] Determine the mass flow rate of steam forindustrial purposes produced in the steam generator.
d.) [10 points] Determine the efficiency of the Brayton cycle,the efficiency of the Rankine cycle, and the efficiency of thecombined cycle (relative to producing power - do not include thevalue of the industrial steam that is produced).
e.) [10 points] What is the net power produced by the cycle?
f.) [10 points] If natural gas is used to energize the cycle andthe cost of natural gas is NGc = 8$/million Btu determine theyearly fuel cost required to run the plant.
g.) [10 points] Determine the cost associated with producing thesame amount of power using a conventional natural gas fired plantwith efficiency ?conv = 0.34 and the same amount of steam using anatural gas fired boiler. What are the savings per year associatedwith using the combined cycle?
h.) [10 points] If natural gas produces 100 lbm of CO2 permillion Btu, what is the environmental impact of using the combinedcycle versus the conventional natural gas power plant (includepower and industrial steam generated).
