Discussion Forum
Que.  A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick of fiber glass insulation (k = 0.05 W/m degree). If the inside and outside convective coefficients are 10 W/m² degree and 5 W/m² degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mm 
a.  1.789 W/m² degree 
b.  2.789 W/m² degree 
c.  3.789 W/m² degree 
d.  4.789 W/m² degree 
Correct Answer:2.789 W/m² degree
