A radiator plate of 0.2-m (wide) x 0.4-m (height) is in a room of 22C. One side (the hot side facing the room) of the radiator plate is maintained at a temperature of 80C, the other sides are assumed to be insulated, as shown in Figure 1. If the following assumptions can be made: 1) steady operating conditions exist; 2) the air an ideal gas; 3) the local' atmospheric pressure is 1.00 atm: (a) Briefly and qualitatively analyze the four different locations for the radiators marked A), B), C) and D), as shown in Figure 1, and rank them in terms of heat transfer efficiency by natural convection. (b) Determine the rate of heat transfer from the radiator plate by natural convection if the plate is A) vertical and C) horizontal with the hot surface facing down. Compare the two and provide a brief discussion of the findings. wall A 0.4 mi C 0.4 m 0.4 m B floor ceiling 0.4 m wall Nu Nu=0.59Ra Nu-0.1 Raa 0.387Ral Nu- - {0.825 + 11 + (0.492/Pr)162) (complex but more accurate) Use vertical plate equations for the upper surface of a cold plate and the lower surface of a hot plate Replace g by g cose Nu-0.54Ra Nu-0.15Ra Nu = 0.27Ral for Ra < 10