Chapter 11, Problem 11.4P

A steel tube $\left(k=50\text{ W/m}\cdot \text{K}\right)$ of inner and outer diameters $D_i=20$ mm and $D_o=26$ mm, respectively, is usedto transfer heat from hot gases flowing over the tube $\left(h_h=200{\text{ W/m}}^2\cdot \text{K}\right)$ to cold water flowing through the tube $\left(h_c=8000{\text{ W/m}}^2\cdot \text{K}\right)$ . What is the cold-side overallheat transfer coefficient $U_c$ ? To enhance heat transfer, 16 straight fins of rectangular profile are installed longitudinally along the outer surface of the tube. The finsare equally spaced around the circumference of thetube, each having a thickness of 2 mm and a length of 15 mm. What is the corresponding overall heat transfercoefficient $U_c$ ?