#### Free Convection: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

##### Example Problem 1

A flat plate is oriented vertically in quiescent (still) air. The surface of the plate has a temperature of \(T_s\) = 90°C. The air has a temperature of \(T_∞\) = 25°C.

- Show whether the flow over the plate due to free convection is laminar or turbulent.
- Calculate the average heat transfer coefficient over the surface of the plate, \(\bar{h}\), in units of W/m
^{2}-K. - Calculate the total rate of heat transfer from the right surface of the plate, in units of Watts.

##### Example Problem 2

Consider two scenarios: In scenario I, the upper surface of a horizontal heated plate causes air to rise upward, away from it. In scenario II, the lower surface of a horizontal heated plate causes air to rise upward, toward it. The plates’ surfaces have a temperature of \(T_s\) = 90°C. The air has a temperature of \(T_∞\) = 25°C. Calculate the average heat transfer coefficients for both scenarios, in units of W/m^{2}-K.