Two concentric spheres of diameter D1 = 0.9 mand D2 = 1.2 mare separated by an air space and have surface temperatures of T1 = 410 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 = i W (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with & = 0.5 and ɛ2 = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ɛ2 = 0.05, ɛj = 0.5, and Dj = 0.9 m, in W? 912 = i W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (ɛ2 = 1.0) and with & = 0.5, D2 = 20 m, and D = 0.9 m, in W? 912 = i W

Two concentric spheres of diameter D1 = 0.9 mand D2 = 1.2 mare separated by an air space and have surface temperatures of T1 = 410 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 = i W (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with & = 0.5 and ɛ2 = 0.05, in W? 912 = W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ɛ2 = 0.05, ɛj = 0.5, and Dj = 0.9 m, in W? 912 = i W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (ɛ2 = 1.0) and with & = 0.5, D2 = 20 m, and D = 0.9 m, in W? 912 = i W

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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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