Effective thermal conductivity in BCC and FCC lattices for all volume fractions and conductivity ratios: Analyses by microstructural efficiency and morphology factor and analytic models

Abstract

The effective thermal conductivity of composite materials is of great interest for thermal storage applications demanding rapid charge and discharge behaviour. Open cell porous metal foams filled with phase change material are one class of composite in which small changes in morphology lead to large changes in effective conductivity. Regular lattices can be easily built by additive manufacturing techniques, but are often used as simple analogues of composites materials with randomly distributed particles or irregular foams, that can thus be studied using computational techniques. Through procedural steady state simulation of heat transfer through unit cells, the impact of morphology on the thermal response of spheres upon BCC and FCC lattices is quantified. The indices of normalised effective thermal conductivity, microstructural efficiency and morphology factor are given for all volume fractions and conductivity ratio 10−4 to 104. Simple empirical models are developed and are compared to experimental data. Recommendations are made on the most optimal morphology for combinations of volume fraction and conductivity ratio.