
302 Heat Transfer: Thermal Management of Electronics
Again, this equation can be used to calculate the convection heat transfer coef-
cient over the top surface of a cold plate surrounded by a hotter uid. Comparing
Equation 12.48 with 12.47 shows that the convection heat transfer is more efcient
in the latter case.
Example 12.2
Consider the electronic enclosure of Example 11.1 shown again in Figure 12.9 and
assume that the surface temperature of the duct is the same as the temperature of
the boards. Calculate the natural convection heat transfer rate from the top and
bottom surfaces of the duct to the air at 25°C.
Solution
Using the calcula ...