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, while 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, while 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