ME 3333 Chapter : Homework 10 Solutions Fall 2012
Document Summary
A small turbine delivers 150 kw and is supplied with steam at 700 c, 2 mpa. The exhaust passes through a heat exchanger where the pressure is 10 kpa and exits as saturated liquid. Find the specific turbine work, and the heat transfer in the heat exchanger. Turbine: energy eq. 6. 13: wt = h1 h2. Entropy eq. 9. 8: s2 = s1 + st gen. Inlet state: table b. 1. 3 h1 = 3917. 45 kj/kg, s1 = 7. 9487 kj/kg k. Ideal turbine st gen = 0, s2 = s1 = 7. 9487 = sf2 + x sfg2. State 3: p = 10 kpa, s2 < sg => saturated 2-phase in table b. 1. 2. X2,s = (s1 - sf2)/sfg2 = (7. 9487 - 0. 6492)/7. 501 = 0. 9731. H2,s = hf2 + x hfg2 = 191. 8 + 0. 9731 2392. 8 = 2520. 35 kj/kg wt,s = h1 h2,s = 1397. 05 kj/kg m. / wt,s = 150 / 1397 = 0. 1074 kg/s.
