Chapter 10 Boiling and Condensation10-75E Saturated steam at a saturation pressure of 0.95 psia and thus at a saturation temperature of Tsat= 100°F (Table A-9E) condenses on the outer surfaces of 144 horizontal tubes which are maintained at 80°F by circulating cooling water and arranged in a 12 ×12 square array. The rate of heat transfer to the cooling water and the rate of condensation of steam are to be determined. Assumptions1Steady operating conditions exist.2The tubes are isothermal. n= 144 tubes80°F L= 15 ftP= 0.95 psia Cooling water Saturated steam PropertiesThe properties of water at the saturation temperature of 100°F are hfg= 1037 Btu/lbm and ρv= 0.00286 lbm/ft3. The properties of liquid water at the film temperature of 100 + 80)/2 = 90°F are (Table A-9E), TTTfs=+()/sat2(=ρμνμlllllpllk==⋅==°⋅°621218420 02965099903583../...lbm / ftlbm / ft hft / hC Btu/lbmFBtu / h ft F2Analysis(a) The modified latent heat of vaporization is Btu/lbm1051=F)80F)(100Btu/lbm999.0(0.68+Btu/lbm1037)(68.0sat*°−°⋅×=−+=splfgfgTTChhThe heat transfer coefficient for condensation on a single horizontal tube is FftBtu/h1562ft)F(1.2/12
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