An uninsulated steam pipe is used to transport high-temperature steam from one building to another. The pipe is of 0.5-m diameter, has a surface temperature of 150°C, and is exposed to ambient air at -10°C. The air moves in cross flow over the pipe with a velocity of 5 m/s.

(a) What is the heat loss per unit length of pipe?

(b) Consider the effect of insulating the pipe with a rigid urethane foam (k = 0.026 W/m ∙ K). Evaluate and plot the heat loss as a function of the thickness 8 of the insulation layer for 0 < 8 < 50 mm.