Consider a layer of insulation installed around a steam pipe. The radius of the pipe is R1 and the thickness of the insulation is R3-R1.The stream is maintained at a temperature TW and the air surrounding the insulation is at a temperature To and flows cross wise over the pipe. The air is flowed over the steam pipe at high enough velocity so a thermal boundary layer develops over the surface described by a heat transfer coefficient h.

Required:
Beginning with the heat equation, calculate the total quantity of heat being conducted per unit time (heat flow) through the insulation, Q (units: energy/time).