Chapter 3, Problem 3.29P

A mild-steel cylindrical billet 25 cm in diameter is to be raised to a minimum temperature of $\text{760°C}$ by passing it through a 6-m long strip-type furnace. If the furnace gases are at $\text{1538°C}$ and the overall heat transfer coefficient on the outside of the billet is ${\text{68 W/m}}^{\text{2}}\text{K}$, determine the maximum speed at which a continuous billet entering at $\text{204°C}$ can travel through the furnace.