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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

PORE-LEVEL DETERMINATION OF REPRESENTATIVE ELEMENTARY VOLUMES FOR EXTINCTION COEFFICIENTS OF METAL FOAMS

Get access (open in a dialog) DOI: 10.1615/IHTC16.rti.022501
pages 8243-8252

Abstract

Open-cell metal foams are currently attracting attention as filling materials in various high-temperature systems. The concept of Representative Elementary Volume is of great importance and evokes wide interests. For this purpose, Representative Elementary Volumes required to characterize extinction coefficients of open-cell metal foams were investigated through combining 3-D tomography images and Monte Carlo Ray-Tracing method in the limit of geometrical optics. Five realistic nickel foams with high porosity from 0.87 to 0.97 and pore density from 10 to 40 PPI were used as samples. Textural features of these foams were first obtained by scanning electron microscope technique. Then, foam structures were rebuilt through computed tomography technique. Subsequently, the anisotropic extinction coefficients were modeled and computed using a Monte Carlo Ray-Tracing method based on a mean free path calculation. The findings indicated that anisotropic characteristics hold significant role in distinct directions. This anisotropic feature gets narrowed when a low porosity and a high pore density are possessed by a foam. In addition, a thick enough foam is required by the characterization of converged extinction coefficient. At least 3 foam cells are needed to ensure the representativeness and reproducibility when a pore-level simulation inside foam materials is conducted. These findings should be considered as valuable contributions to the thermal application of metal foams.