Circular copper rod of diameter D = 1 mm and length L = 25 mm are used to enhance heat transfer from a surface that is maintained at Ts.1 = 100°C. One end of the rod is attached to this surface (at x = 0), while the other end (x = 25 mm) is joined to a second surface, which is maintained at Ts.2 = O°C. Air flowing between the surfaces (and over the rods) is also at a temperature of Too = O°C, and a convection coefficient of h = 100 W/m2 ∙ K is maintained.

(a) What is the rate of heat transfer by convection from a single copper rod to the air?

(b) What is the total rate of heat transfer from a 1-m by I-m section of the surface at 100°C, if a bundle of the rods is installed on 4-mm centers?