Unformatted text preview: W 9 . 276 ) C 150 250 )( C J/kg. 1023 )( kg/s 002708 . ( ) ( = ° − ° = − = e i p T T C m Q & & The logarithmic mean temperature difference and the surface area are C 82 . 79 250 110 150 110 ln 250 150 ln ln ° = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − − − = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − − − = Δ i s e s i e T T T T T T T 2 2 ln ln m 0.02891 ) C 82 . 79 )( C . W/m 120 ( W 9 . 276 = ° ° = Δ = ⎯→ ⎯ Δ = T h Q A T hA Q s s & & Then the tube length becomes cm 30.7 = = = = ⎯→ ⎯ = m 3067 . m) 03 . ( m 0.02891 2 ππ π D A L DL A s s The rate of evaporation of water is determined from kg/h 0.442 = kg/s 0001227 . kJ/kg) 2257 ( kW) 2769 . ( = = = ⎯→ ⎯ = fg evap fg evap h Q m h m Q & & & & 86...
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 Fall '10
 Dr.DanielArenas
 Thermodynamics, Convection, Force, Mass

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