Thermodynamics HW Solutions 938

Thermodynamics HW Solutions 938 - Chapter 12 Radiation Heat...

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Chapter 12 Radiation Heat Transfer 12-45 A long semi-cylindrical duct with specified temperature on the side surface is considered. The temperature of the base surface for a specified heat transfer rate is 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 emissivity of the side surface is ε = 0.4. Analysis We consider the base surface to be surface 1, the side surface to be surface 2. This system is a two-surface enclosure, and we consider a unit length of the duct. The surface areas and the view factor are determined as 2 2 2 1 m 571 . 1 2 / m) 1 )( m 0 . 1 ( 2 / m 0 . 1 ) m 0 . 1 )( m 0 . 1 ( = = = = = ππ DL A A (summation rule) 1 1 0 1 12 12 12 11 = ⎯→ = + ⎯→ = + F F F F The temperature of the base surface is determined from K 684.8 = ⎯→ + × = ε ε + σ = 1 2 2 4 4 1 4 2 8 2 2 2 12 1 4 2 4 1 12 ) 4 . 0 )( m 571 . 1 ( 4 . 0 1
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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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