Thermodynamics HW Solutions 923

Thermodynamics HW Solutions 923 - Chapter 12 Radiation Heat...

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Chapter 12 Radiation Heat Transfer 12-31 A long cylindrical rod coated with a new material is placed in an evacuated long cylindrical enclosure which is maintained at a uniform temperature. The emissivity of the coating on the rod is to be determined. Assumptions 1 Steady operating conditions exist 2 The surfaces are opaque, diffuse, and gray. Properties The emissivity of the enclosure is given to be ε 2 = 0.95. Analysis The emissivity of the coating on the rod is determined from () + × = + = 10 1 95 . 0 95 . 0 1 1 ] K 200 K 500 )[ K W/m 10 67 . 5 ]( m) m)(1 01 . 0 ( [ W 8 1 1 ) ( 1 4 4 4 2 8 2 1 2 2 1 4 2 4 1 1 12 ε π σ r r T T A Q & D 2 = 0.1 m T 2 = 200 K ε 2 = 0.95 D 1 = 0.01 m T 1 = 500 K ε 1 = ? Vacuum which gives ε 1 = 0.074 12-32E The base and the dome of a long semicylindrical duct are maintained at uniform temperatures. The net rate of radiation heat transfer from the dome to the base surface is to be determined.
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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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