Multiple Bi-phase Interfaces in a PCM Layer Subject to Periodic Boundary Conditions Characteristic of Building External Walls

The thermal fields, which form in a PCM layer subject to external and internal loadings that operate on the external wall of buildings, are determined by a physical model that describes conduction in the solid phase and the liquid phase and the phase change of the melting temperature with a thermal balance equation at the bi-phase interface. The system of equations is resolved with a finite difference numerical model that uses a resolution algorithm that provides for the contemporaneous presence of one or more bi-phase interfaces in the layer. The thermal analysis in steady periodic regime conditions by a layer situated in Turin has highlighted that layer behaviour varies monthly in relation to the number and position of the bi-phase interfaces that form in the layer.