Consider a cuboidal furnace (l = 5 m, b = 4 m, h = 3 m), whose surfaces closely approximate black surfaces. The base, top, and side surfaces of the furnace are maintained at uniform temperatures of (1040) K, (840) K, and (540) K, respectively. Determine (a) the net rate of radiation heat transfer between the base and the side surfaces, (b) the net rate of radiation heat transfer between the base and the top surface, and (c) the net radiation heat transfer from the base surface.

Consider a cuboidal furnace (l = 5 m, b = 4 m, h = 3 m), whose surfaces closely approximate
black surfaces. The base, top, and side surfaces of the furnace are maintained at uniform
temperatures of (1040) K, (840) K, and (540) K, respectively. Determine (a)
the net rate of radiation heat transfer between the base and the side surfaces, (b) the net rate of
radiation heat transfer between the base and the top surface, and (c) the net radiation heat
transfer from the base surface.

Steam in a heating system flows through tubes whose outer radius is r1 = (3) cm and whose
walls are maintained at a temperature of 127 °C. Circular aluminum fins (k = 180 W/m K) of
outer radius r2 = (6) cm and constant thickness t = 1 mm are attached to the tube. The space
between the fins is 3 mm. Heat is transferred to the surrounding air at 27 °C, with a combined
heat transfer coefficient of 60 W/m2 K. Determine the increase in heat transfer from the tube
per meter of its length as a result of adding fins