Two large horizontal and parallel plates are separated from each other by 3 mm of quiescent atmospheric air. The top surface is at −20 ◦C, and the bottom surface is at 15 ◦C. (a) Calculate the heat...

Two large horizontal and parallel plates are separated from each other by 3 mm of quiescent atmospheric air. The top surface is at −20 ◦C, and the bottom surface is at 15 ◦C.

(a) Calculate the heat flux that is exchanged between the two surfaces.

(b) Repeat the calculation, this time assuming that the distance between the two plates is 3 cm.