Question 4 (15 marks) A steam power plant operates between a high (boiler) pressure of 3.0...

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Question 4 (15 marks) A steam power plant operates between a high (boiler) pressure of 3.0 MPa and a low (condenser) pressure of 10 kPa. 4.1 To increase the thermal efficiency and also to reduce the moisture component in the exhaust steam at the end of the expansion, the steam in the boiler is superheated to 400 °C. Calculate the thermal efficiency of the steam power plant if it operates on a Rankine cycle. Boiler Pump Feedwater heater 1kg 4.2 To further increase the thermal efficiency with regeneration, an open-style feedwater heater is inserted into the cycle with an extraction pressure of 800 kPa, as shown in Fig. Q4.2. Show the cycle on a T-s diagram and find the mass ratio of the steam extracted, m,. Given: h6=2891.6 kJ/kg, superheated vapour at state 6. Turbine Pump ₁kg (1-m₁) kg Condenser Figure Q4.2 for Question 4.2 Boiler Pump (1-m₁) kg Turbine Condenser Figure Q4.1 for Question 4.1 Question 4 (15 marks) A steam power plant operates between a high (boiler) pressure of 3.0 MPa and a low (condenser) pressure of 10 kPa. 4.1 To increase the thermal efficiency and also to reduce the moisture component in the exhaust steam at the end of the expansion, the steam in the boiler is superheated to 400 °C. Calculate the thermal efficiency of the steam power plant if it operates on a Rankine cycle. Boiler Pump Feedwater heater 1kg 4.2 To further increase the thermal efficiency with regeneration, an open-style feedwater heater is inserted into the cycle with an extraction pressure of 800 kPa, as shown in Fig. Q4.2. Show the cycle on a T-s diagram and find the mass ratio of the steam extracted, m,. Given: h6=2891.6 kJ/kg, superheated vapour at state 6. Turbine Pump ₁kg (1-m₁) kg Condenser Figure Q4.2 for Question 4.2 Boiler Pump (1-m₁) kg Turbine Condenser Figure Q4.1 for Question 4.1

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