Effect of the shape and the distribution of cells on the effective thermal conductivity of polyurethane foam

Abstract

AbstractTo design foams with specific properties, it is important to be able to predict their effective properties. The objective of this study is to compare and quantify the effect of the geometrical parameters on the thermal properties. Then the study uses both analytical and numerical homogenization methods to connect micro‐scale parameters to the macro‐scale thermal behavior. Several statistical studies of the morphology have been used to model the different categories of PU foams. The foam is modeled by a periodic structure of open, closed, or mixed cells. For each type of cell, different idealized shapes of a single cell are used, while keeping a constant porosity for each category. In the case of mixed cells, the effect of the relative positioning of cells is investigated. The results show that the effective thermal conductivity is considerably impacted by the cell shape. Moreover, the geometrical modeling of the struts, in the heuristic modeling, has also an important effect. Furthermore, the relative position of gas cavities, in the spherical representation, influences the effective thermal conductivity. However, the distribution of open and closed cells, in the case of mixed cell foam, has a limited effect.