Chapter 5, Problem 5.67P

As part of a heat treatment process, cylindrical, 304 stainless steel rods of 100-mm diameter are cooled from an initial temperature of $500°\text{C}$ by suspending them in an oil bath at $30°\text{C}\text{.}$ If a convection coefficient of $500{\text{W/m}}^{\text{2}}\cdot \text{K}$ is maintained by circulation of the oil, how long does it take for the centerline of a rod to reach a temperature of $50°\text{C,}$ at which point it is withdrawn from the bath? If 10 rods of length $L=1\text{m}$ are processed per hour, what is the nominal rate at which energy must be extracted from the bath (the cooling load)?