Thermodynamics HW Solutions 201

Thermodynamics HW Solutions 201 - Chapter 15 Steady Heat...

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Chapter 15 Steady Heat Conduction 3-68 A steam pipe covered with 3-cm thick glass wool insulation is subjected to convection on its surfaces. The rate of heat transfer per unit length and the temperature drops across the pipe and the insulation are 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 center line and no variation in the axial direction. 3 Thermal conductivities are constant. 4 The thermal contact resistance at the interface is negligible. Properties The thermal conductivities are given to be k = 15 W/m °C for steel and k = 0.038 W/m °C for glass wool insulation Analysis The inner and the outer surface areas of the insulated pipe per unit length are AD L L ii oo == = + = ππ (. ( . . ( . 005 1 0157 0 055 0 06 1 0 361 m) m) m m 2 2 R i T 1 R 2 R o T 2 R 1 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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