Question

In a manufacturing process, long aluminum rods of square cross section with d = 25 mm are cooled from an initial temperature of Ti = 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[infinity] = 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 Tsur = 20°C.

Answer 1

The required cooling time is 613 s and configuration 1 (face of the rod) should be used.

Step-by-step explanation:

please look in the image.