Simultaneous determination of intrinsic solid phase conductivity and effective thermal conductivity of Kelvin like foams

The relationship of geometrical parameters with thermal properties such as effective thermal conductivity is critical for conductive heat transfer in metal foams. We have realized different virtual isotropic structures of tetrakaidecahedron shape having circular, square, hexagon, diamond and star strut shapes with various orientations using CAD modeling. The range of solid to fluid phase conductivity ratios (lambda(s)/lambda(f)) studied is from 10 to 30,000 for porosity range 60-95%. At pore scale, 3-D direct numerical simulations were performed to calculate effective thermal conductivity, lambda(eff) in local thermal equilibrium condition. A database of 2000 values of effective thermal conductivity is generated. Two models are derived in order to predict simultaneously intrinsic solid phase thermal conductivity, lambda(s) and effective thermal conductivity, lambda(eff). A modified correlation factor, F is introduced in analytical resistor model in order to take thermal conductivities of constituent phases into account and a new PF model based on Lemlich model is derived. An excellent agreement has been observed between the predicted results against numerical and experimental data. We have also shown the importance of intrinsic solid phase thermal conductivity (lambda(s)) in determining effective thermal conductivity (lambda(eff)). (C) 2014 Elsevier Ltd. All rights reserved.