Two concentric spheres of diameter D1of T1 = 390 Kand T, = 300 K.= 0.7 m and D2 = 1.2 mare separated by an air space and have surface temperatures(a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W?912w(b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with & = 0.5 and &2 = 0.05, inW?912(c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ez = 0.05, e1 = 0.5, and Di = 0.7 m, in w?412 =(d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with ej = 0.5, D2 =20 m, and Di = 0.7 m, in W?iw912 =Physical Properties Mathematical Functions

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Two concentric spheres of diameter Di = 0.7 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 390 K and T, = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 w (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with e1 = 0.5 and €2 = 0.05, in w? 912 = w (c) What is the net rate of radiation exchange if D, is increased to 20 m, with ez = 0.05, ej = 0.5, and Di = 0.7 m, in W? 912 w (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (€2 = 1.0) and with & = 0.5, D2 = 20 m, and Di = 0.7 m, in W? 912 =

Two concentric spheres of diameter Di = 0.7 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 390 K and T, = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 w (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with e1 = 0.5 and €2 = 0.05, in w? 912 = w (c) What is the net rate of radiation exchange if D, is increased to 20 m, with ez = 0.05, ej = 0.5, and Di = 0.7 m, in W? 912 w (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (€2 = 1.0) and with & = 0.5, D2 = 20 m, and Di = 0.7 m, in W? 912 =

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.30P

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11.31 A large slab of steel 0.1 m thick contains a 0.1 -m-di- ameter circular hole whose axis is normal to the surface. Considering the sides of the hole to be black, specify the rate of radiative heat loss from the hole. The plate is at 811 K, and the surroundings are at 300 K.
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Two concentric spheres of diameter Dj = 0.8 mand D2 T1 = 400 K and T2 = 300 K. = 1.2 m are separated by an air space and have surface temperatures of (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 i (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with e = 0.5 and e2 = 0.05, in W? 912 i w (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with &2 = 0.05, ɛ 1 = 0.5, and Di = 0.8 m, in W? 912 w = 1.0) and with ej = 0.5, D2 = 20 m, (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 and Di = 0.8 m, in W? 912 = i W
Two concentric spheres of diameter Di = 0.7 mand D2 = 1.2 mare separated by an air space and have surface temperatures of T = 400 K and T, = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? ৭12 = w (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with ɛi = 0.5 and e2 = 0.05, in W? 12 (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with e2 = 0.05, e1 = 0.5, and Di = 0.7 m, in W? 912 = i (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (e2 = 1.0) and with e = 0.5, D2 = 20 m, and D1 = 0.7 m, in W? w 912 = Physical Properties Mathematical Functions
Two concentric spheres of diameter D = 0.9 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 390 Kand T2 = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = i w (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with ej = 0.5 and ez = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with e, = 0.05, e = 0.5, and D = 0.9 m, in W? 912 = (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with e1 = 0.5, D2 = 20 m, and D, = 0.9 m, in W? 412 =
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Two concentric spheres of diameter D = 0.7 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 400 K and T, = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with & = 0.5 and &2 = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with &2 = 0.05, €1 = 0.5, and D1 = 0.7 m, in W? 912 = W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (82 = 1.0) and with &1 = 0.5, D2 = 20 m, and D = 0.7 m, in W? 912 = W