Chapter 9, Problem 9.9P

Consider an array of vertical rectangular tins, which is to be used to cool an electronic device mourned in quiescent, atmospheric air at $T_{\infty }=27°C$ . Each fin has $L=20\text{mm}$ and $H=150\text{mm}$ and operates at anapproximately uniform temperature of $T_s=77°C$ .

(a) Viewing each tin surface as a vertical plate in an infinite, quiescent medium, briefly describe why there exists an optimum fin spacing S. Using Figure 9.4, estimate the optimum value of S for the prescribed conditions.
(b) For the optimum value of S and a fin thickness of $t=1.5\text{mm}$ , estimate the rate of heat transfer from the fins for an array of width W = 355 mm.