A steam at 3 MPa and 5 kg/s is entering into an isentropic steam turbine and leave with 100 kPa and 200°C (see Figure Q1). 7% steam at 500 kPa is diverted to a heat exchanger to preheat the feed water with the second outlet from the turbine. (a) Considering the necessary assumptions determine the power output of the turbine in kW. (b) Discuss the conditions for a turbine to operate in an isentropic condition. Compare intuitively the power output of a real turbine and isentropic turbine. (c) The entropy of an actual turbine process increases as a result of irreversibility. To maintain the entropy of the seam at the exit at lower value, it is recommended to use cold water and circulate in the turbine so that the entropy and enthalpy remain at low value when it leaves the turbine, and hence the work output will increase. How do you evaluate this recommendation in improving the efficiency of the turbine?
A steam at 3 MPa and 5 kg/s is entering into an isentropic steam turbine and leave with 100 kPa and 200°C (see Figure Q1). 7% steam at 500 kPa is diverted to a heat exchanger to preheat the feed water with the second outlet from the turbine.
(a) Considering the necessary assumptions determine the power output of the turbine in kW.
(b) Discuss the conditions for a turbine to operate in an isentropic condition. Compare intuitively the power output of a real turbine and isentropic turbine.
(c) The entropy of an actual turbine process increases as a result of irreversibility. To maintain the entropy of the seam at the exit at lower value, it is recommended to use cold water and circulate in the turbine so that the entropy and enthalpy remain at low value when it leaves the turbine, and hence the work output will increase. How do you evaluate this
recommendation in improving the efficiency of the turbine?
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