In a manufacturing process, long aluminum rods of square cross section with d = 25 mm are cooled from an initial temperature of T_i = 400°C. Which configuration in the sketch should be used to minimize the time needed for the rods to reach a safe-to-handle temperature of 60°C when exposed to air in cross flow at V = 8 m/s, T_∞ = 30°C? What is the required cooling time for the preferred configuration? The emissivity of the rods is ε = 0.10 and the surroundings temperature is T_sur =  20°C.

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V.T d Tut