Two concentric spheres of diameter D) = 0.8 m and D 1 = 1.2 m are separated
Question:
Two concentric spheres of diameter D) = 0.8 m and D1 = 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?
(b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with ε1 = 0.5 and ε2 = 0.05?
(c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ε2 = 0.05, ε1 = 0.5, and D1 = 0.8 m? What error would be introduced by assuming blackbody behavior for the outer surface (ε2 = 1), with all other conditions remaining the same?
(d) For D2 = 1.2 m and emissivities of E) = 0.1, 0.5, and 1.0, compute and plot the net rate of radiation exchange as a function of ε2 for 0.05 < ε2 < 1.0.
Step by Step Answer:
Fundamentals of Heat and Mass Transfer
ISBN: 978-0471457282
6th Edition
Authors: Incropera, Dewitt, Bergman, Lavine