12-37 Two concentric spheres of diameters D₁ = 0.3 m and D₂ = 0.8 m are maintained at uniform temperatures T₁ = 700 K and T₂ = 400 K and have emissivities &₁ = 0.5 and &2 = 0.7, respectively. Determine the net rate of radiation heat transfer between the two spheres. Also, determine the convec- tion heat transfer coefficient at the outer surface if both the sur- rounding medium and the surrounding surfaces are at 30°C. Assume the emissivity of the outer surface is 0.35.

12-37 Two concentric spheres of diameters D₁ = 0.3 m and D₂ = 0.8 m are maintained at uniform temperatures T₁ = 700 K and T₂ = 400 K and have emissivities &₁ = 0.5 and &2 = 0.7, respectively. Determine the net rate of radiation heat transfer between the two spheres. Also, determine the convec- tion heat transfer coefficient at the outer surface if both the sur- rounding medium and the surrounding surfaces are at 30°C. Assume the emissivity of the outer surface is 0.35.

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.

Chapter11: Heat Transfer By Radiation

Section: Chapter Questions

Problem 11.23P

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