Question

In a regenerative ideal Rankine cycle, hot water steam enters the turbine at 10 MPa and 480°C. condenser inlet pressure is 10 kPa. Some steam is taken from the turbine at a pressure of 0.7 MPa, feeds a Closed Feed water heater and is sent to the condenser as a saturated liquid at a pressure of 0.7 MPa at the outlet. The other outlet (cold) is at a pressure of 10 MPa and a saturation temperature of 0.7 MPa. According to this information a) Draw the flow chart of the cycle. b) Calculate the amount of heat transferred to the system per unit mass c) Calculate the ratio of the amount of steam received from the turbine to the closed feed water heater to the entire mass in the system. d) Calculate the thermal efficiency of the cycle.

Answer 1

1 kg/sec TO MPa 480C 0.7mpay 2 1-x) B Qin х © cooling waters 10 MPa Condensen fum Pump Closed feed water Heaten ® ng=ng (throttling 0-7 Sat Flow Chart of the bankine cycle. from superheated steam table h,= 3321•4 KJ/kg and si = 6.5282 kg/kgk at 10 mpa, 485c. - and B ② isentropic process. s sis₂ = 53 = 6.5282 kJ/kg k... State is within vapour dome. 30, S₂ = Sf (at 0.7MPa) + J Spoog (at on 7 MPa). >> 6-5282 = 1.9922 + 72x4.7158 -) Z2 = 0.9619 12 = (1 - 0.9619)x 697.22 + 0-9619 x 2763-5 2699.8 kJ/kg similarly for state point ③ 33 = Sf (at 10 kPa) + Ja Espg (ut lokea) 6.5282 = 0-6492 + Y 37.5010 IJz = 0.7837 I nz= 191.81+ 0.7837 x 2392.8 2067.196 kr/kg ha= f(at lokPa) = 191.8 nga hat vfx (10x103 - 10) kJ 1kg = 191-81 +001010 x (10000-10) 201.899 K3/kg ks/ kg

(3321.4 - 2094-8) +1-. 253) 2091-8-2067-196) hy he (at 0.7 MPa) = 697.20 Ks kes/rg he = hz + 6 (0.7 MPa) (10-0.7) x16 3. ,, thos = 707.50 kilky let assume x traction of Steam extracted at 0.7 MPa from turbine 30, X- ho-h5 707.50 - 201-899 2694.8 - 697.20 = 0.2531 hahz heat thansfered the system (hinho) (33214 - 767.50) Ks/ky (Qiu) - - 2613.9 K3/kg (3) thermal efficiency we - WP Qin (haha) + (1-x) (mg-hy) - (ng-ha) (hi-he (201-89-191-81) 2613.9 - 0.4152 41-52. (A) bor olol