Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Open-cell solid foams are rigid skeletons permeable to fluids, which are used as direct heaters or thermal dissipaters in many industrial applications. Using dielectric materials for the skeleton and exposing them to microwaves is an efficient way to heat these excellent susceptors. The heating performance depends on the permittivity of the skeleton. However, a rigorous description of the effective permittivity is challenging and requires an appropriate consideration of the complex skeletal foam morphology. In this contribution, we propose Platonic solids as building elements of the open-cell skeletal structures to describe their effective permittivity. The derived new simplistic geometrical relation is used along with electromagnetic wave propagation calculations in representatives of the real foam. A geometrical parameter-free relation was then obtained, which is only based on foam porosity and the material´s permittivity. The derived relation enables efficient and reliable estimation of the effective permittivity of open-cell foams over a large range of porosity.