Thermodynamics HW Solutions 853

Thermodynamics HW Solutions 853 - Chapter 10 Boiling and...

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Chapter 10 Boiling and Condensation 10-76E Saturated steam at a saturation pressure of 0.95 psia and thus at a saturation temperature of T sat = 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. Assumptions 1 Steady operating conditions exist. 2 The tubes are isothermal. n = 144 tubes 80 ° F L = 15 ft P = 0.95 psia Cooling water Saturated steam Properties The properties of water at the saturation temperature of 10 ° F are h fg = 1037 Btu/lbm and ρ v = 0.00286 lbm/ft 3 . The properties of liquid water at the film temperature of 100 + 80)/2 = 90 ° F are (Table A-9E), TT T fs =+ () / sat 2 ( = ρ μ νμ l l ll l pl l k = =⋅ == ° ° 6212 1842 0 02965 0999 0358 3 . . /. . . lbm / ft lbm / ft h ft / h C B t u / l b m F Btu / h ft F 2 Analysis ( a ) The modified latent heat of vaporization is Btu/lbm 1051 = F ) 80 F)(100 Btu/lbm 999 . 0 ( 0.68 + Btu/lbm 1037 ) ( 68 . 0 sat * ° ° × = + = s pl fg fg T T C h h The heat transfer coefficient for condensation on a single horizontal tube is F ft Btu/h 1374 ft) F(2.0/12
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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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