A horizontal cylinder of diameter and length L is subjected to constant temperatures T1 and T2

A horizontal cylinder of diameter Ф and length L is subjected to constant temperatures T1 and T2 (T1> T2). Yes, It is assumed that the lateral face of the cylinder is perfectly isolated from the environment and that its thermal conductivity. It varies in the form k (T) = 5 + 30T. Determine the heat transfer per unit area through the cylinder.