Chapter 3 Steady Heat Conduction3-126EA row of used uranium fuel rods are buried in the ground parallel to each other. The rate of heat transfer from the fuel rods to the atmosphere through the soil is to be determined. Assumptions1Steady operating conditions exist.2 Heat transfer is two-dimensional (no change in the axial direction). 3 Thermal conductivity of the soil is constant. PropertiesThe thermal conductivity of the soil is given to be k= 0.6 Btu/h⋅ft⋅°F. Analysis The shape factor for this configuration is given in Table 3-5 to be 5298.0)ft12/8()ft15(2sinh)ft12/1()ft12/8(2ln)ft3(242sinh2ln24total=⎟⎟⎠⎞⎜⎜⎝⎛πππ×=⎟⎠⎞⎜⎝⎛πππ×=wzDwLSThen the steady rate of heat transfer from the fuel rods becomes T2= 60°F8 inT1= 350°F15 ftD = 1 inL = 3 ftBtu/h92.2=°−°=−=C)60350)(FBtu/h.ft.6.0)(ft5298.0()(21totalTTkSQ&3-127Hot water flows through a 5-m long section of a thin walled hot water pipe that passes through the center of a 14-cm thick wall filled with fiberglass insulation.
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