#### Steady-state Heat Conduction in Planar Walls: Screencast

Shows how to write a thermal circuit for a composite wall with two different materials in series and parallel.

We suggest that after watching this screencast, you list the important points as a way to increase retention.

##### Important Equations:

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