Thermal conductivity model of open-cell foam suitable for wide span of porosities

In this work, an effective thermal conductivity (ETC) model of open cell foam composite is proposed based on regular pentagonal dodecahedron geometrical model, considering the realistic shape of ligaments, hollowness in ligaments and ligament orientations. Compared with other ETC models, this model exhibits higher accurate predictions with respect to the available experimental data in a wide span of porosities spanning from about 0.6 up to 1. Results show that the ETC of foam composites will increase with increase of the hollowness of ligaments at the same foam porosity. For a high porosity, the influence of the hollowness of ligaments on the ETC is negligible when the foam material has a high TC. The ETC of copper foam-paraffin composite predicted by our model agrees well with that obtained by experimental methods carried out in this work, both suggest that the ETC almost linearly depend on the melting degree of paraffin. According to the linear dependence of ETC on the melting degree of paraffin, the melting degree of the paraffin in copper foam-paraffin composite can be roughly obtained by fitting our model to the experimental ETC. The model developed in this work is expected to give an accurate prediction of open cell foam composites, and also could be applied to evaluate the melting degree of phase change materials in open cell foam composites. (C) 2018 Elsevier Ltd. All rights reserved.