Chapter 3, Problem 3.155P

Determine the percentage increase in heat transfer associated with attaching aluminum fins of rectangular profile to a plane wall. The tins are 50 mm long,0.5 mm thick, and are equally spaced at a distance of 4 mm (250 fins/m). The convection coefficient associated with the bare wall is $40{\text{W/m}}^{\text{2}}\cdot \text{K,}$ while that resulting from attachment of the fins is $30{\text{W/m}}^{\text{2}}\cdot \text{K}\text{.}$