Thermodynamics HW Solutions 911

Thermodynamics HW Solutions 911 - Chapter 12 Radiation Heat...

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Chapter 12 Radiation Heat Transfer 12-16 The view factors between the rectangular surfaces shown in the figure are to be determined. Assumptions The surfaces are diffuse emitters and reflectors. Analysis We designate the different surfaces as follows: shaded part of perpendicular surface by (1), bottom part of perpendicular surface by (3), shaded part of horizontal surface by (2), and front part of horizontal surface by (4). ( a ) From Fig.12-6 25 . 0 3 1 3 1 23 1 2 = = = F W L W L and 32 . 0 3 1 3 2 ) 3 1 ( 2 1 2 = = = + F W L W L 3 m (1) (3) 1 m 1 m 1 m (2) 1 m (4) 07 . 0 25 . 0 32 . 0 : rule ion superposit 23 ) 3 1 ( 2 21 23 21 ) 3 1 ( 2 = = = ⎯→ + = + + F F F F F F 0.07 = = = = 21 12 21 2 12 1 2 1 : rule y reciprocit F F F A F A A A ( b ) From Fig.12-6, 15 . 0 3 2 and 3 1 3 ) 2 4 ( 1 2 = = = + F W L W L and 22 . 0 3 2 and 3 2 ) 3 1 ( ) 2 4 ( 1 2 = = = + + F W L W L 07 . 0 15 . 0 22 . 0 : rule ion superposit 1 ) 2 4 ( 3 ) 2 4 ( 1 ) 2 4 ( ) 3 1 ( ) 2 4 ( = = + = + + + + + F F F F 14 . 0 ) 07 . 0 ( 3 6 : rule y reciprocit 1 ) 2 4 ( 1 ) 2 4 ( ) 2 4 ( 1 ) 2 4 ( 1 1 1 ) 2 4 ( ) 2 4 ( = = = = + + + + + + F A A F F A F A 3 m (1) (3) 1 m 1 m 1 m 1 m (4) (2) 0.07 = = + = + 07 . 0 14 . 0 : rule ion superposit 14 12 14 ) 2 4 ( 1 F F F F since = 0.07 (from part a ). Note that in part ( b ) is equivalent to in part ( a ). F 12 F 14 F 12 ( c ) We designate shaded part of top surface by (1), remaining part of top surface by (3), remaining part of bottom surface by (4), and
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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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