Solve the following problem:
Q: Coatings applied to long metallic strips are cured by installing the strips along the walls of a long oven of square cross section. Thermal conditions in the oven are maintained by a long silicon carbide rod (heating element), which is of diameter D = 20 mm and is operated at T1 = 1700 K. Each of two strips on one side wall has the same orientation relative to the rod (s1 = 60 mm, s2 = 20 mm, L = 80 mm) and is operated at T2 = 600 K. All surfaces are diffuse and gray with e1 = 0.9 and e2 = 0.4. Assuming the oven to be well insulated at all but the strip surfaces and neglecting convection effects, determine the heater power requirement per unit length (W/m).
