(i) A cylindrical pipe of length L has inner and outer radii as a and b respectively. The inner surface of the pipe is at a temperature `T_(1)` and the outer surface is at a lower temperature of `T_(2)`. Calculate the radial heat current if conductivity of the mate- rial is K.
(ii) A cylindrical pipe of length L has two layers of material of conduc- tivity `K_(1)` and `K_(2)`. (see figure). If the inner wall of the cylinder is maintained at `T_(1)` and outer surface is at `T_(2) (lt T_(1))`, calcu- late the radial rate of heat flow.

Answer

(i) `((T_(1)-T_(2))2piKL)/(ln((b)/(c)))`
(ii) `(T_(1)-T_(2))/((1)/(2piK_(1)L)ln((r^(2))/(r^(1)))+(1)/(2piK_(2)L)ln((r_(3))/(r_(2))))`