A power cycle operating steadily is shown below. The boiler (a heat exchanger to boil liquid...

 

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A power cycle operating steadily is shown below. The boiler (a heat exchanger to boil liquid water) produces steam at an absolute pressure of 20 MPa and a temperature of 600°C (State 1). Steam leaving the boiler enters a high-pressure turbine (HPT) and expands to an absolute pressure of 4 MPa and temperature of 360°℃ (State 2). A fraction of the steam (y) is extracted at State 2 and the remaining fraction of the steam (1 - y) expands in a low-pressure turbine (LPT) to an absolute pressure of 100 kPa and a quality of 92% (State 3). Steam leaving the LPT is cooled in a condenser and exits as saturated liquid at an absolute pressure of 100 kPa (State 4). Saturated liquid water leaving from the condenser is pumped to an absolute pressure of 4 MPa and a temperature of 100°C (State 5) in a low-pressure pump (LPP). Liquid leaving the LPP (State 5) is mixed with the extracted steam (State 2) in a rigid, insulated mixing chamber. The mixed stream exits the mixing chamber as saturated liquid at an absolute pressure of 4 MPa (State 6). Saturated liquid water leaving from the mixing chamber is pumped to an absolute pressure of 20 MPa and a temperature of 255°C (State 7) in a high-pressure pump (HPP) and is supplied to the boiler to heat it back in the boiler. Assume that both turbines and pumps are adiabatic. P₁ = 20 MPa T₁ = 600°C steam Boiler HPT P, = 20 MPa T7= 255°C Extracted Steam = P₂ = 4 MPa T₂ = 360°C HPP ym steam Mixing Chamber LPT P54 MPa LPP P6= 4 MPa T5 = 100°C sat. liquid Remaining Steam = (1-y)m steam P3= 100 kPa X3 = 0.92 Condenser P4 = 100 kPa sat. liquid (a) Determine the fraction of steam (y) extracted at State 2. (b) Find specific work (per unit mass flow rate leaving the boiler) for the HPT and LPT, in kJ/kg. (c) Calculate specific work (per unit mass flow rate leaving the boiler) for the LPP and HPP, in kJ/kg. (d) Find specific heat transfer for the boiler, in kJ/kg. (e) Calculate specific heat transfer (per unit mass flow rate leaving the boiler) for the condenser, in kJ/kg. A power cycle operating steadily is shown below. The boiler (a heat exchanger to boil liquid water) produces steam at an absolute pressure of 20 MPa and a temperature of 600°C (State 1). Steam leaving the boiler enters a high-pressure turbine (HPT) and expands to an absolute pressure of 4 MPa and temperature of 360°℃ (State 2). A fraction of the steam (y) is extracted at State 2 and the remaining fraction of the steam (1 - y) expands in a low-pressure turbine (LPT) to an absolute pressure of 100 kPa and a quality of 92% (State 3). Steam leaving the LPT is cooled in a condenser and exits as saturated liquid at an absolute pressure of 100 kPa (State 4). Saturated liquid water leaving from the condenser is pumped to an absolute pressure of 4 MPa and a temperature of 100°C (State 5) in a low-pressure pump (LPP). Liquid leaving the LPP (State 5) is mixed with the extracted steam (State 2) in a rigid, insulated mixing chamber. The mixed stream exits the mixing chamber as saturated liquid at an absolute pressure of 4 MPa (State 6). Saturated liquid water leaving from the mixing chamber is pumped to an absolute pressure of 20 MPa and a temperature of 255°C (State 7) in a high-pressure pump (HPP) and is supplied to the boiler to heat it back in the boiler. Assume that both turbines and pumps are adiabatic. P₁ = 20 MPa T₁ = 600°C steam Boiler HPT P, = 20 MPa T7= 255°C Extracted Steam = P₂ = 4 MPa T₂ = 360°C HPP ym steam Mixing Chamber LPT P54 MPa LPP P6= 4 MPa T5 = 100°C sat. liquid Remaining Steam = (1-y)m steam P3= 100 kPa X3 = 0.92 Condenser P4 = 100 kPa sat. liquid (a) Determine the fraction of steam (y) extracted at State 2. (b) Find specific work (per unit mass flow rate leaving the boiler) for the HPT and LPT, in kJ/kg. (c) Calculate specific work (per unit mass flow rate leaving the boiler) for the LPP and HPP, in kJ/kg. (d) Find specific heat transfer for the boiler, in kJ/kg. (e) Calculate specific heat transfer (per unit mass flow rate leaving the boiler) for the condenser, in kJ/kg.

Answer rating: 100% (QA)

a Determine the fraction of steam y extracted at State 2 To determine the fraction of steam y extracted at State 2 we can perform an energy balance on the mixing chamber Since the mixing chamber is ri... View the full answer