Water is the working fluid in a regenerative Rankine cycle with one closed feedwater heater. Steam enters the turbine at 1400 lbf/in.2 and 1000°F and expands to 120 lbf/in.2, where some of the steam is extracted and diverted to the closed feedwater heater. The remaining steam expands through the second-stage turbine to the condenser pressure of 5 lbf/in.2 Each turbine stage and the pump have isentropic efficiencies of 80%. Flow through the condenser, closed feedwater heater, and steam generator is at constant pressure. Condensate exiting the feedwater heater as saturated liquid at 120 lbf/in.2 undergoes a throttling process as it passes through a trap into the condenser. The feedwater leaves the heater at 1400 lbf/in.2 and a temperature equal to the saturation temperature at 120 lbf/in.2 The net power output of the cycle is 1 x 109 Btu/h. Determine for the cycle: (a) the mass flow rate of steam entering the first stage of the turbine, in lb/h. (b) the rate of heat transfer, in Btu/h, to the working fluid passing through the steam generator. (c) the percent thermal efficiency.
Water is the working fluid in a regenerative Rankine cycle with one closed feedwater heater. Steam enters the turbine at 1400 lbf/in.2 and 1000°F and expands to 120 lbf/in.2, where some of the steam is extracted and diverted to the closed feedwater heater. The remaining steam expands through the second-stage turbine to the condenser pressure of 5 lbf/in.2 Each turbine stage and the pump have isentropic efficiencies of 80%. Flow through the condenser, closed feedwater heater, and steam generator is at constant pressure. Condensate exiting the feedwater heater as saturated liquid at 120 lbf/in.2 undergoes a throttling process as it passes through a trap into the condenser. The feedwater leaves the heater at 1400 lbf/in.2 and a temperature equal to the saturation temperature at 120 lbf/in.2 The net power output of the cycle is 1 x 109 Btu/h.
Determine for the cycle:
(a) the mass flow rate of steam entering the first stage of the turbine, in lb/h.
(b) the rate of heat transfer, in Btu/h, to the working fluid passing through the steam generator.
(c) the percent thermal efficiency.
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