In the case where there is a multilayer wall of more than one material present, as shown in Fig. 4.3-1, we proceed as follows. The temperature profiles in the three materials A, B, and C are shown. Since the heat flow q must be the same in each layer, we can write Fourier's equation for each layer as
Solving each equation for ΔT,
Adding the equations for T1 − T2, T2 − T3, and T3 − T4, the internal ...