Thermodynamics HW Solutions 492

Thermodynamics HW Solutions 492 - Chapter 5 Numerical...

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Chapter 5 Numerical Methods in Heat Conduction 5-94 A refrigerator whose walls are constructed of 3-cm thick urethane insulation malfunctions, and stops running for 6 h. The temperature inside the refrigerator at the end of this 6 h period is to be determined. Assumptions 1 Heat transfer is one-dimensional since the walls are large relative to their thickness. 2 Thermal properties, heat transfer coefficients, and the outdoor temperature are constant. 3 Radiation heat transfer is negligible. 4 The temperature of the contents of the refrigerator, including the air inside, rises uniformly during this period. 5 The local atmospheric pressure is 1 atm. 6 The space occupied by food and the corner effects are negligible. 7 Heat transfer through the bottom surface of the refrigerator is negligible. Properties The conductivity and diffusivity are given to be k = 1.4 W/m. ° C and . The average specific heat of food items is given to be 3.6 kJ/kg. ° C. The specific heat and density of air at 1 atm and 3 ° C are C α
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This note was uploaded on 01/22/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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