g Quiescent Air Disk Tsur = Tx = 300 K -Ed,2 = 0.9 -Ed.1 = 1.0 -T₂, ₂ = 1 -T₁, &₁ = 0.6 L= 0.5 m D=1m

A circular disk (ignore its thickness) of D = 1 m diameter is placed over a barbecue pit maintained
at T1 = T2 = 600 K. The upper surface of the disk is exposed to quiescent ambient air and
surroundings at 300 K. The bottom surface and top surface of the disk has emissivities of d,1 = 1.0
and d,2 = 0.9, respectively. The bottom and cylindrical side surface of the barbecue pit have
emissivities of 1 = 0.6 and 2 = 1.0, respectively. Assume the disk and barbecue pit surfaces are
diffuse and gray.
A) Determine the net heat transfer rate to the cover, qnet,d, when Td = 500 K.
B) Plot qnet,d as a function of the disk temperature for 300 K < Td < 600 K, using Excel or
MATLAB. What is the steady-state temperature of the disk?