Chapter 10 Boiling and Condensation10-47E Saturated steam at a saturation temperature of Tsat= 95°F condenses on the outer surfaces of horizontal pipes which are maintained at 85°F by circulating cooling water. The rate of heat transfer to the cooling water and the rate of condensation per unit length of a single horizontal pipe are to be determined.Assumptions1Steady operating conditions exist.2The pipe is isothermal. 3 There is no interference between the pipes (no drip of the condensate from one tube to another). PropertiesThe properties of water at the saturation temperature of 95°F are hfg= 1040 Btu/lbm and ρv= 0.0025 lbm/ft3. The properties of liquid water at the film temperature of TTTfs=+=()/sat2(95 + 85)/2 = 90°F are (Table A-9E), ρμνμlllllpllk==⋅==°⋅°621218420 02965099903583../...lbm / ftlbm / ft hft / hC Btu/lbmFBtu / h ft F2Steam95°F...................85°FCondensate flow AnalysisThe modified latent heat of vaporization is Btu/lbm1047=F)85F)(95Btu/lbm999.0(0.68+Btu/lbm1040)(68.0sat*°−°⋅×=−+=splfgfgTTChhNoting that we have condensation on a horizontal tube, the heat transfer coefficient is determined from
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