Question

Water is the working fluid in an ideal Rankine cycle with reheat. Superheated vapor enters the turbine at 8 MPa, 480℃, and the condenser pressure is 8 kPa. Steam expands through the first stage turbine to 700 kPa and then is reheated to 480℃. Assumptions: see problem 1 . Determine for the cycle

(a) the rate of heat addition, in kJ per kg to the working fluid in the steam generator.

(b) the thermal efficiency.

(c) the rate of heat transfer from the working fluid passing through the condenser to the cooling water.

Assumptions/Engineering Model:

1. Each component of the cycle is analyzed as a control volume at steady state.

2. All processes of the working fluid are internally reversible.

3. The turbine and pump operate adiabatically.

4. Kinetic and potential energy effects are negligible.

5. Condensate exits the condenser as saturated liquid.

Answer 1

2 A P, 8MPA PaO.7MPA 6 Peond =s Pa 4 P, = 8MPa T,-480c ha3233.3 P T4 50e Sx =. 6.559 KIKk S E rSy 3399. S hy - 6.7266 T-TA hi-ha S1-Sn hy-hx Ty -Ta Sy-Sn 3349.02E3 hi P O. MPa = 700 EPa ha =ha263.8 Pa0.MPa, Ta 4goc Pa o.6 MPa T 400 c ha 320. 9 SA=1.309 T 48 C S = TY 3483, 4 Sy .0041 .k At 480'c 3440.86 S- 7.94 52 Y

For PE .8 MPa Si 7.5.3 3 h Sy7.8692 3 481.3 hy KS/re. k S = 7.81 P o Me PE o.6 MPa ha = 3440:88 = 7.9 4S2 S h32 P 0. MPa hy =3 438.S8 Sy= 7.8 Py = o.8 MPa h3 3439. 73 S2 =7.879 6 n).at 8 k Pa 10 3x(8000 -8)s 7.992 Krg Wp hihë h 168.75 3.363#7,192 hy= 1918 - he 173.362 P7g

Saz Sq = 732年6 7g k Sf S4 = Seg Sp こ0-6492 7.8776= 0:59088 t 久KG6389 6 子,63894 73.362 t 0ASXQ40 2.66 h 688'SSヤで

(h,-he ths-h a2 3349.02-181. sa) + (3439.33 -2762.8) 3%44.596 KT/ka. hi h th3- he) (3349. 02-27 62 8) + ( 3 4 39.73 -24sr 8 84) 1S70 06 -5/*g . S70.06t 7.993 100 3844 59 6 4 o.63 h4 - ho 2455. B89-173.3 62 2288,522