Question

Assume a regenerative feedwater heating steam cycle with two closed feedwater heaters and one open feedwater heater/deaerator. steam enters the turbine at 100 bars, 5400c. overall efficiency of the steam turbine is 0.87. condenser pressure is 0.05 bar. drain from the last closed fwh returns back to the condenser. furthermore, we have the following data known; feed water temperature before entering the boiler is 2000c. temperature at the outlet of the open feedwater heater is 1100c and the pressure is 1.25 times the admission pressure. where the admission pressure is 100 bars as mentioned earlier. the work from the condenser pump can be ignored. the thermal temperature difference (ttd) is taken 20c for both closed fwhs. there is no drain cooling (drain water leaves the closed heaters in saturated condition. find the percentage mass flow rates which goes into each heater. whenever needed, an equal amount of feed water heating can be assumed along the heaters to calculate the unknown temperatures

Answer 1

The problem requires the calculation of percentage mass flow rates in a regenerative feedwater heating steam cycle with known parameters and conditions, including the absence of drain cooling and specific pressures and temperatures. It is solved using thermodynamic principles, notably energy and mass balances.

Step-by-step explanation:

The question pertains to the calculation of percentage mass flow rates in a regenerative feedwater heating steam cycle with specific given parameters such as steam entering the turbine pressure and temperature, the thermal temperature difference (TTD) for the closed feedwater heaters (FWHs), and the overall efficiency of the steam turbine. The absence of drain cooling and the return of the last closed FWH drain back to the condenser are also important conditions to consider. This problem involves applying concepts of thermodynamics, particularly the principles of heat transfer and the conservation of mass and energy within a steam cycle. The use of an energy balance would help to calculate the unknown temperatures and the mass flow rates going into each heater. To solve this problem, one would typically use the First Law of Thermodynamics and create energy balance equations around each component of the cycle such as the turbines, feedwater heaters, and boiler. The aim is to calculate the feedwater heating from the different heaters and determine the corresponding mass flow rates.