A 50-cm-diameter pipeline in the Arctic carries hot oil at 30C and is exposed to a surrounding

Question:

A 50-cm-diameter pipeline in the Arctic carries hot oil at 30ºC and is exposed to a surrounding temperature of −20ºC.Aspecial powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7mW/m · ºC. The convection heat-transfer coefficient on the outside of the pipe is 9 W/m2 · ºC. Estimate the energy loss from the pipe per meter of length.