Question

Water is the working fluid in a modified Rankine cycle with superheat and reheat. Water as superheated vapor enters the high-pressure stage turbine at 60 bar and 440 C and leaves at 5 bar as liquid-vapor mixture with a quality of xa-0.98. It is then reheated to 400 °C at the same pressure of 5 bar before entering the second stage turbine where it expands to a pressure of 0.1 bar and a mixture quality of x0.96. The condenser pressure is 0.1 bar and water is leaving the condenser as saturated liquid. The pump delivers liquid water at the pressure of 60 bar. It can be assumed that the pump operates without irreversibilities. The cycle runs at steady state conditions with a mass flowrate of 0.1 kg/s. Fill out the specific enthalpy values in the table state provided and determine for the cycle: a) The net power delivered, in kW b) The total rate of heat transfer to the working fluid passing through the steam generator, in kW c) The thermal efficiency d) The back work ratio 1. quality D KJ/kg C bar - 440 60 1 TP2) X-0.98 2 5 400 3 Tdp)x0.96 0.1 4 0.1 T(ps) 5 60 6 T

Answer 1

1 3 Pr 4 Gwen data 60 ban P5 ban = 01bcn T= 440°C CP.K Nag Foom table at 1nlet t tenbinc - P= 6mpa at 400C Te mp at 4500c h=3177.2 Ke S=6.54 h3301 8 14J S=6 72 0 By into palation at T=440°c 3276.8 kT at point 2 2 hi t ht totttt-a 98 - 27 06:5능 640.21 t 0. 38 (9108.5) 8606+0.9O( 4.9606) 6.72

at state-3 p 5 ban T2900c h33270.2 KS) Mg S2=770781/ae at State-4 Isat=45a1'c asume dny ness taoten x G .6492 7.50O assame plcess 3-4 1sentoopic St $3 4 S3=7.7078 11 0.6992 + x75010) = 7.7078 191.81 +0.994 C 2392.8) ha khty xh. ha d4 43.48 State -5 5= 19101 I5 b Pump (6o00 -10) 010010La

-197.86 KI)as 91 1+605 Totel eneng uppered as heat bi-he) = 3276.8 197.8) +(32702- -9706.5) 36 42.64 3642.64 X = 364.264 Ku 1 Ci-ha)(haha) -wp net wark done (32 76.8-270615) + (32702- 2443. 98) 6 05 13 90 .97 FT Net Powen Phct 139.697 Ra ST M ten bine oan (-h) t Chaha) 1397.02 KJ wnet xi00 139.09y100 = 3818y. Qsupperea 364,269 Wp 6.05 bacb coasb natio 13 97.02 4.33 X10-3