Unformatted text preview: × Δ = → Δ = − lbf 1 ft/s lbm 2 . 32 ft) s)(80 lbm/ft 10 039 . 1 ( 128 ft) (0.08 ) ( /s ft 0.00201 128 2 3 4 3 4 horiz μ P L D P V & It gives psi 0.0358 = = Δ 2 lbf/ft 16 . 5 P Then the useful pumping power requirement becomes ft/s lbf 0.737 W 1 ) lbf/ft 16 . 5 )( /s ft 00201 . ( 2 3 u pump, W 0.014 = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅ = Δ = P V W & & Checking The flow was assumed to be laminar. To verify this assumption, we determine the Reynolds number: 1922 s lbm/ft 10 039 . 1 ft) ft/s)(0.08 4 . )( lbm/ft 42 . 62 ( Re 3 3 = ⋅ × = = − ρ D m V which is less than 2300. Therefore, the flow is laminar. Discussion Note that the pressure drop across the water pipe and the required power input to maintain flow is negligible. This is due to the very low flow velocity. Such water flows are the exception in practice rather than the rule. 847...
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 Fall '10
 Dr.DanielArenas
 Fluid Dynamics, Thermodynamics, Convection, Force, Mass, Power, horiz, 0.04 ft, 0.8 ft, 0.08 ft, 0.014 W

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