Thermodynamics HW Solutions 837

Thermodynamics HW Solutions 837 - Chapter 10 Boiling and...

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Chapter 10 Boiling and Condensation 10-54 Saturated steam at a pressure of 4.25 kPa and thus at a saturation temperature of T sat = 30 ° C (Table A-9) condenses on the outer surfaces of 100 horizontal tubes arranged in a 10 × 10 square array maintained at 20 ° C by circulating cooling water. The rate of heat transfer to the cooling water and the rate of condensation of steam on the tubes are to be determined. Assumptions 1 Steady operating conditions exist. 2 The tubes are isothermal. Properties The properties of water at the saturation temperature of 30 ° C are h fg = 2431 × 10 3 J/kg and ρ v = 0.030 kg/m 3 . The properties of liquid water at the film temperature of 30 + 20)/2 = 25 ° C are (Table A-9), TT T fs =+ () / sat 2 ( = ρ μ νμ l l ll l pl l k = == × =⋅ ° ° 997 0 0891 10 0894 10 4180 0607 3 3 6 . . /. . kg / m kg / m s m/ s C J / k g C W/m C 2 Analysis ( a ) The modified latent heat of vaporization is n = 100 tubes 20 ° C L = 8 m P = 4.25 kPa Cooling water Saturated steam hh C fg fg pl s * .( ) × °− ° × 068 2431 10 20) 10 33 sat J / kg + 0.68 4180 J / kg C(30 C = 2,459 J / kg The heat transfer coefficient for condensation on a single horizontal tube is
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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