Radiative characteristics of Voronoi open-cell foams made from semitransparent media

Abstract

The radiative characterization of open-cell foams made from semitransparent solids is more complex than that made from opaque media. This study aims to understand how the component radiative properties and structural parameters of such open-cell foams affect their radiative characteristics. A radiative transfer model was established in the limit of geometric optics for the radiative characterization of a family of numerically generated Voronoi foams with open cells. It considers the reflection and refraction at the solid surface and the transmission, absorption and scattering process inside the solid phase. It is found that when the solid phase is in reality partially transparent, the opaque solid assumption will lead to inaccurate outcomes. Strongly scattering solid phase may cause much radiative energy to be rejected via reflection behavior, which will weaken the absorptive capability of the foam sheets as radiation absorbers. In addition, the radiative transfer model established was applied in three popular ceramic foams (alumina, silicon carbide and zirconia). The model shows advances in the field of analyzing and explaining the spectral radiative characteristics of ceramic foams. The present work can provide useful guidance when open-cell foams made from semitransparent media become potential candidates for thermal applications.