For a composite wall with no heat generation:

The equation for heat flux is:

\[ q=\frac{T_0\, -\, T_4}{R_{total}}\]

where \(T_0\) = temperature of the left side of the left wall

\(T_4\) = temperature on the right side of the right wall

\(R_{total}\) = total resistance to heat transfer

\[R_{total} = \sum_{i=1}^{4} \frac{x_i}{k_i}\]

where \(x_i\) = thickness of each wall segment (cm)

\(k_i\) = thermal conductivity of the wall’s material (W/[cm K])

The wall temperatures can be calculated from left to right according to:

\[T_i = T_{i-1}\, -\, qR_i = T_{i-1}\, -\, q\frac{x_i}{k_i}\]

where \(R_i\) = thermal resistance

\(T_i\) = temperature