Question

Refer to Figure 3 (below), depicting a regenerative Rankine cycle with a closed feedwater heater (CFWH) when considering the following system description. Saturated liquid water at a pressure of P before entering the CFWH. 12 kPa is pumped to a pressure of Pi-5 MPa After leaving the CFWH as a saturated liquid, the water continues to a Steam Generator which heats the water to a temperature of Ts 600°C. This superheated steam is used to drive a Turbine. A quantity of steam is bled from the Turbine at the point where the steam expands to a pressure of 1.2 MPa. This stream of steam is directed into the CFWH. The remainder of the steam within the Turbine expands to a pressure of 12 kPa. The bleed from the Turbine is turned into saturated water in the CFWH and this drain cascades through a throttle to the condenser Assume ideal conditions: that the isentropic efficiency of the turbine and the pump are 100%, and that there is no pressure loss through the heat exchanger, steam generator or condenser rm Turbine 5 (1 - a) m, Steam Generator Condenser Closed 1 Pump Heater Figure 3 - Rankine Cycle with a Closed Feedwater Heater (Figure 7.22 Reisel 2015) Calculate the enthalpy and the entropy of the water/steam at each state and use this information to fill out a table like that shown in Table 3 in your answer booklets. You may include other properties in your table. State h (kJk s (kJ/kg.K) Table 3-Enth entropy of described system Using these, give the appropriate equation for and calculate i) The energy transferred as heat in the steam generator in kJ/kg. ii) The flow of water bled from the turbine which is directed to the closed feedwater heater expressed as a fraction of the total flow rate through the steam generator iii) The energy transferred as heat in the condenser in kJ per kg output water iv) The total work output of the turbine in kJ per kg input steam. v) The total work required to drive the pump in kJ/kg. vi) The net work of the cycle in kJ per kg into the turbine vii) The thermal efficiency of the entire cycle viii) Draw the cycle on a T-s diagram.

Answer 1

% @ 12kP9 6 isentsopte compressto ih Pump 5 0.001012( 5xto-12 205-462-t 2l0.SI kJ| c T8-33 kk 7 2-2159 Kg lkgk balante the tonduns hs-h - 798 33-205462 2326 -23-205.412

0.781 (3150-798-33) = ha-210.5) 2 2047.164 3666.-2047-14+ (i-0-1H)(292023-205.4)+013-205 46) 926.16 kJlk, (u。Thal work output of tasuw -Cb66 . 9-3150)HU-c าย) (3150-2320-23)

the 210-9-205.442. 25:04 8 RS 619-62- S.08 Wrok 0 693.572 16i9-73 0282 42.82