Two concentric spheres of diameter Dị = 0.8 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T1 = 400 K and T2 = 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 e = 0.5 and e2 = 0.05, in W? 912 (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with e2 0.05, €1 0.5, and DI 0.8 m, in W? %3D 912 (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (e2 = 1.0) and with & = 0.5, D2 and Di = 0.8 m, in W? = 20 m, 912 = i

Two concentric spheres of diameter Dị = 0.8 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T1 = 400 K and T2 = 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 e = 0.5 and e2 = 0.05, in W? 912 (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with e2 0.05, €1 0.5, and DI 0.8 m, in W? %3D 912 (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (e2 = 1.0) and with & = 0.5, D2 and Di = 0.8 m, in W? = 20 m, 912 = i

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.45P

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