The herein paper aims to provide a new concept for equivalent thermal conductivity evaluation in case of multi-layers structures based on several theoretical models from the technical literature. Series and parallel distribution with respect of the heat flux leads to an equivalent thermal conductivity that characterize the overall behavior of the entire structure. Variations with respect of particle volume fraction and coefficient representing the ration between the physical parameters of the layers (e.g. surface area) for different theoretical models and combinations will be also shown to support the conclusions. The aspects presented can be easily inserted in computer programs in order to conduct an optimization process of the structure under study.