Multi-layered wall
The goal of this virtual lab is to illustrate the computation of the steady-state heat conduction in a three-layered wall. The steady-state heat conduction is assumed to be one-dimensional.

The wall is composed of three layers of different materials and thickness LA, L B an LC . The temperature of the inner surface of the wall is T1 and the outside temperature T4 (see figure 1).
The heat flow per unit area (qx )and the temperature at the interfaces of the diferent layers (T 2, T3 ) are calculated.
Thermal conductivities of the layer's materials (kA , kB , kC ) are assumed to be independent of others model variables. The thickness of the layer that compose the walls are model parameters. The wall surface (S) is assumed to be constant. The S parameter is not used in the model equations, because qx doesn't depend on this parameter.

The mathematical model is described by the following equations:
T1 - T2 = (La/ka)  *  qx T2 - T3 = (Lb/kb)  *  qx T3 - T4 = (Lc/kc)  *  qx