Two parallel disks of diameter D = 3 ft separated by L = 2 ft are located directly on top of each other. The disks are separated by a radiation shield whose emissivity is 0.15. Both disks are black and are maintained at temperatures of 1200 R and 700 R, respectively. The environment that the disks are in can be considered to be a blackbody at 540 R. Determine the net rate of radiation heat transfer through the shield under steady conditions.

T, = 1200 R 1 ft 3= 0.15 1 ft T2 = 700 R