Thermodynamics HW Solutions 751

# Thermodynamics HW Solutions 751 - Chapter 9 Natural...

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Chapter 9 Natural Convection 9-77 A vertical plate in water is considered. The forced motion velocity above which natural convection heat transfer from the plate is negligible is to be determined. Assumptions 1 Steady operating conditions exist. Properties The properties of water at the film temperature of ( T s + T )/2 = (60+25)/2 = 42.5 ° C are (Table A-15) υ β = 065 10 0 00040 6 . . m/ s K 2 -1 Analysis The characteristic length is the height of the plate L c = L = 5 m. The Grashof and Reynolds numbers are × = × = = × = × = = V V L V L T T g Gr s 6 2 6 13 2 2 6 3 -1 2 2 3 10 6 . 4 /s m 10 65 . 0 ) m 5 ( Re 10 063 . 4 ) /s m 10 65 . 0 ( ) m 5 )( K 25 60 )( K 0004 . 0 )( m/s 81 . 9 ( ) ( Water T = 25 ° C V Plate, T s = 60 ° C L = 5 m and the forced motion velocity above which natural convection heat transfer from this plate is negligible is m/s 2.62 = ⎯→ = × × ⎯→ = V V Gr 1 . 0 ) 10
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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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