Thermodynamics HW Solutions 263

Thermodynamics HW Solutions 263 - Chapter 3 Steady Heat...

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Chapter 3 Steady Heat Conduction 3-153E Steam is produced in copper tubes by heat transferred from another fluid condensing outside the tubes at a high temperature. The rate of heat transfer per foot length of the tube when a 0.01 in thick layer of limestone is formed on the inner and outer surfaces of the tube is to be determined. Assumptions 1 Heat transfer is steady since there is no indication of any change with time. 2 Heat transfer is one-dimensional since there is thermal symmetry about the centerline and no variation in the axial direction. 3 Thermal properties are constant. 4 Heat transfer coefficients are constant and uniform over the surfaces. Properties The thermal conductivities are given to be k = 223 Btu/h ft °F for copper tubes and k = 1.7 Btu/h ft °F for limestone. Analysis The total thermal resistance of the new heat exchanger is & & () . Q TT R R Q new total,new total,new new 4 F 21 0 B t u / h h. F / Btu = ⎯→ ⎯= = −° × ∞∞ 12 350 250 0005
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This note was uploaded on 01/19/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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