Thermodynamics HW Solutions 175

Thermodynamics HW Solutions 175 - Chapter 3 Steady Heat...

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Chapter 3 Steady Heat Conduction 3-35 The wall of a refrigerator is constructed of fiberglass insulation sandwiched between two layers of sheet metal. The minimum thickness of insulation that needs to be used in the wall in order to avoid condensation on the outer surfaces is to be determined. Assumptions 1 Heat transfer through the refrigerator walls is steady since the temperatures of the food compartment and the kitchen air remain constant at the specified values. 2 Heat transfer is one- dimensional. 3 Thermal conductivities are constant. 4 Heat transfer coefficients account for the radiation effects. Properties The thermal conductivities are given to be k = 15.1 W/m °C for sheet metal and 0.035 W/m °C for fiberglass insulation. Analysis The minimum thickness of insulation can be determined by assuming the outer surface temperature of the refrigerator to be 10 ° C. In steady operation, the rate of heat transfer through the
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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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