Thermodynamics HW Solutions 503

Thermodynamics HW Solutions 503 - Chapter 5 Numerical...

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Chapter 5 Numerical Methods in Heat Conduction 5-114E The roof of a house initially at a uniform temperature is subjected to convection and radiation on both sides. The temperatures of the inner and outer surfaces of the roof at 6 am in the morning as well as the average rate of heat transfer through the roof during that night are to be determined. Assumptions 1 Heat transfer is one-dimensional since the roof is large relative to its thickness. 2 Thermal properties, heat transfer coefficients, and the indoor temperatures are constant. 3 Radiation heat transfer is significant. 4 The outdoor temperature remains constant in the 4-h blocks. 5 The given time step Δ t = 5 min is less than the critical time step so that the stability criteria is satisfied. Properties The conductivity and diffusivity are given to k = 0.81 Btu/h.ft. ° F and . The emissivity of both surfaces of the concrete roof is 0.9. α 74 10 6 .
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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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