Thermodynamics HW Solutions 214

Thermodynamics HW Solutions 214 - Chapter 15 Steady Heat...

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Chapter 15 Steady Heat Conduction 3-79E Steam exiting the turbine of a steam power plant at 100 ° F is to be condensed in a large condenser by cooling water flowing through copper tubes. For specified heat transfer coefficients and 0.01-in thick scale build up on the inner surface, the length of the tube required to condense steam at a rate of 400 lbm/h 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 tube and be k = 0.5 Btu/h ft °F for the mineral deposit. The heat of vaporization of water at 100 ° F is given to be 1037 Btu/lbm. Analysis When a 0.01-in thick layer of deposit forms on the inner surface of the pipe, the inner diameter of the pipe will reduce from 0.4 in to 0.38 in. The individual thermal resistances are
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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