problem4-29 - PROBLEM 4.29 KNOWN: Dimensions and thermal...

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PROBLEM 4.29 KNOWN: Dimensions and thermal conductivity of concrete duct. Convection conditions of ambient ir. Inlet temperature of water flow through the duct. a FIND: (a) Heat loss per duct length near inlet, (b) Minimum allowable flow rate corresponding to aximum allowable temperature rise of water. m SCHEMATIC: ASSUMPTIONS: (1) Steady state, (2) Negligible water-side convection resistance, pipe wall conduction resistance, and pipe/concrete contact resistance (temperature at inner surface of concrete corresponds to that of water), (3) Constant properties, (4) Negligible flow work and kinetic and otential energy changes. p A NALYSIS: (a) From the thermal circuit, the heat loss per unit length near the entrance is () ii conv cond 2D TT q ln 1.08w / D RR 1 2k h4 w π ∞∞ −− == ′′ + + where
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This note was uploaded on 12/07/2010 for the course MAE Heat Trans taught by Professor Lee,j.s. during the Spring '10 term at Seoul National.

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