Thermodynamics HW Solutions 922

# Thermodynamics HW Solutions 922 - Chapter 12 Radiation Heat...

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Chapter 12 Radiation Heat Transfer 12-29 The base and the dome of a hemispherical furnace are maintained at uniform temperatures. The net rate of radiation heat transfer from the dome to the base surface 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. Analysis The view factor is first determined from F FF F 11 11 12 12 0 11 = += →= (flat surface) (summation rule) Noting that the dome is black, net rate of radiation heat transfer from dome to the base surface can be determined from kW 759.4 = × = × = = = W 10 594 . 7 ] ) K 1000 ( ) K 400 )[( K W/m 10 67 . 5 )( 1 ]( /4 ) m 5 ( )[ 7 . 0 ( ) ( 5 4 4 4 2 8 2 4 2 4 1 12 1 12 21 π σε T T F A Q Q & & T 1 = 400 K ε 1 = 0.7 T 2 = 1000 K ε 2 = 1 D = 5 m The positive sign indicates that the net heat transfer is from the dome to the base surface, as expected. 12-30 Two very long concentric cylinders are maintained at uniform temperatures. The net rate of
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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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