Thermodynamics HW Solutions 914

Thermodynamics HW Solutions 914 - Chapter 12 Radiation Heat...

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Chapter 12 Radiation Heat Transfer 12-24E Top and side surfaces of a cubical furnace are black, and are maintained at uniform temperatures. Net radiation heat transfer rate to the base from the top and side surfaces are to be determined. Assumptions 1 Steady operating conditions exist 2 The surfaces are opaque, diffuse, and gray. 3 Convection heat transfer is not considered. Properties The emissivities are given to be ε = 0.7 for the bottom surface and 1 for other surfaces. Analysis We consider the base surface to be surface 1, the top surface to be surface 2 and the side surfaces to be surface 3. The cubical furnace can be considered to be three-surface enclosure with a radiation network shown in the figure. The areas and blackbody emissive powers of surfaces are 2 2 3 2 2 2 1 ft 400 ) ft 10 ( 4 ft 100 ) ft 10 ( = = = = = A A A 2 4 4 2 8 4 3 3 2 4 4 2 8 4 2 2 2 4 4 2 8 4 1 1 Btu/h.ft 866 , 56 ) R 2400 )( R . Btu/h.ft 10 1714 . 0 ( Btu/h.ft 233 , 11 ) R 1600 )( R . Btu/h.ft 10 1714 . 0 ( Btu/h.ft 702 ) R 800 )( R . Btu/h.ft 10 1714 . 0 ( = × = σ = = × = σ = = × = σ = T E T E T E b b b
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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