Coupling inverse fin method with infrared thermography to determine the effective thermal conductivity of extruded thermoplastic foams

Abstract

An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical simulation of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The microstructure heterogeneity of extruded polyethylene foam, in which pores are filled with air with different levels of open and closed porosity, was taken into account. The obtained effective thermal conductivity values were compared with previous results obtained using a numerical solution based on periodic homogenization techniques (NSHT) and the transient plane source technique (TPS) to verify the accuracy of the proposed method. The results show that the suggested method is in good agreement with both NSHT and TPS. Moreover, it is also appropriate for structural materials such as unidirectional fiber-reinforced plastic composites, where heat transfer is very different according to the fiber direction (parallel or transverse to the fibers).