Chapter 4, Problem 4.31P

 A hole of diameter $D=0.25\text{m}$ is drilled through the center of a solid block of square cross section with $w=1\text{m}$ on a side. The hole is drilled along the length, $l=2\text{m,}$ of the block, which has a thermal conductivity of $k=150\text{W/m}\cdot \text{K}\text{.}$ The four outer surfaces are exposed to ambient air. with $T_{\infty ,2}=25°\text{C}$ and $h_2=4{\text{W/m}}^{\text{2}}\cdot \text{K,}$ while hot oil flowing through the hole is characterized by $T_{\infty ,1}=300°\text{C}$ and $h_1=50{\text{W/m}}^{\text{2}}\cdot \text{K}\text{.}$ Determine the corresponding heat rate and surface temperatures.