Steam enters the turbine of a steam power plant that operates on a simple ideal
ID: 1843482 • Letter: S
Question
Steam enters the turbine of a steam power plant that operates on a simple ideal Rankine cycle at a pressure of 6 MPa, and it leaves as a saturated vapor at 7.5 kPa. Steam is cooled in the condenser by the cooling water from a nearby river, which enters the condenser at 15 degree C The previous steam power plant is modified with closed and open feedwater heaters and reheating systems. The high pressure turbine remains at 6 MPa and the low pressure turbine is at 1.60 MPa The inlet temperature of the high pressure turbine remains constant at 1089.18 degree C. Unlike ideal Rankine cycle, the temperature at the inlet of the low pressure turbine is 900 degree C. The condenser pressure is 10 KPa. Steam is extracted from the low pressure turbine at 0.8 MPa for the closed feedwater and at 0.4 MPa for the open feedwater heater. In the closed feedwater heater, the feedwater is heated to 170.41oC The extracted steam leaves the closed feedwater heater as a saturated liquid, which is subsequently throttled to the open feedwater heater. Show the cycle on a T s diagram. Determine (a) the fraction of steam extracted from the turbine for the open feedwater heater, (b) the thermal efficiency of the cycle, (c) the net power output for a mass flow rate of 8.35 kg/s And discuss 1) What would happen if the condenser pressure drops to 2.5 KPa? 2.) Find the state of the new conditions if the pressure at the condenser drops to 2.5 KPa 3.)If Qin remains constant and the pressure at the condenser is 2.5 KPa, how does the work net change and why? 4) Imagine that you bypass the closed feedwater heater, meaning that the feedwater is only heated by the open feedwater heater. This is usually done in Cogeneration processes. Using engineering analysis speculate about the effect (possitive or negative) of the closed feedwater heater on the overall thermal efficiency if the heat provided by the closed feedwater heater is now used for another process, the heat for the process is 3324.11. will the thermal efficiency increase or decrease by implementing the by- pass? How much will it change?Explanation / Answer
The answer of following question is as follows.
The efficiency of cycle decreases because when feed water heater is installed in cycle the work done increases. So when work done increases,the efficiency decreases.