A t = 5 mm thick sheet of anodized aluminum is used to reject heat in a space power application. The edge of the sheet is attached to a hot source, and the sheet is maintained at nearly isothermal conditions at T = 300 K. The sheet is not subjected to irradiation.

(a) Determine the net radiation heat transfer from both sides of the 200 mm x 200 mm sheet to deep space.

(b) An engineer suggests boring 3-mm-diameter holes through the sheet. The holes are spaced 5 mm apart. The interior surfaces of the holes are anodized after they are bored. Determine the net radiation heat transfer from both sides of the sheet to deep space.

(c) As an alternative design, the 3-mm-diameter flat-bottomed holes are not bored completely through the sheet but are bored to depths of 2 mm on each side leaving a 1-mm-thick web of aluminum separating the bottoms of the holes located on opposite sides of the sheet. Determine the net radiation heat transfer from both sides of the sheet to deep space.

(d) Compare the ratio of the net radiation heat transfer to the mass of the sheet for the three designs.