Question

A Rankine steam cycle operates between 250°C and 45°C. The steam entering the
turbine is completely vaporised and the turbine is isentropic. Sketch the process on a T-s
diagram. For this cycle with a steam mass flow of 5 kg/s, find the following:
a. The work done by the turbine
b. The work done by the pump
c. The heat exchange rate from the condenser
d. The cycle efficiency

[4428W;-19.95W; -8614.5W; 33.8%]

Answer 1

metcom 5 /sec $ - $ Cisentropie) $1 = og at 350'c SI = 6.071 kg $2= & = 6.041 @ $2 at 45º = SF + x sty = S2 6.071 - 05638 +xx 7.528 x = 0.217 ha = hft a hfg at 45 - ha - 188.4 + 0.72178 2394.9 h₂ = 1916.799 kJ/kg ne = at 250° = ng = 2800.4 kiing work done by twybine, WT = (hi-h2) We = 5*( 2800.4 – 1916.799) WT = 4418 kine work done by pump, hepump = (hy-h3 ) xmi nepump = ns-n.de = mx 2 x (Po-P2) = mx 275 x 3874461 – 9.59439) x 103 39 75.94 = 5* 0.00100991 x ( 3945.9 - 9.594) X10% 06

Wpump -19.95 Ku - 20 kw condensen hehe) 5x (188.4 - 1916.791 Qcondencey = - 8641-9 kW O negere - here in Whet = Wr-wp = + 4418 – 20 Os - Or = Qs – 8641.9 O $ = 13039.9 Khe 4398 13039.9 Nexcre Rcycle = = L 33.7% "cle