Chapter 1, Problem 1.30P

Two concentric spheres of diameter D1= 0.9 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? q12= Enter your answer for part (a) in accordance to the question statement W (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, in W? q12= Enter your answer for part (b) in accordance to the question statement W (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= 0.9 m, in W? q12= Enter your answer for part (c) in accordance to the question statement W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (ε2= 1.0) and with ε1= 0.5, D2= 20 m, and D1= 0.9 m, in W? q12= Enter your answer for part(d) in accordance to the question statement W