Pore-scale numerical analysis of Kelvin’s metal foam/phase change material composites with different porosities and anisotropy ratios

Coupling metal foams with phase change materials (PCM) is promising in overcoming the PCM low heat transfer capability. Metal foams can be obtained either via standard manufacturing techniques, like the casted method, or via additive manufacturing. In both cases, casted foams can be represented with reference to Kelvin’s foam model, taken as a geometrical model for the former and as a cellular material designed from scratch for the latter. Differently from casted foams, whose anisotropy depends on the manufacturing process, in artificially manufactured structures anisotropy is induced. A discrete pore-scale numerical analysis of the thermal performance of isotropic and anisotropic Kelvin’s metal foam/PCM composites heated from below is herein presented. The enthalpy-porosity method is employed to account for liquid PCM motion; the phase change is modelled using the apparent heat capacity method. The predicted evolution of the melting fraction for different porosities and anisotropy ratios of the foam, the single cell volume being the same, compared well with data taken from the literature. This study shows that higher porosities and the elongation of the cells along the gravity direction increase both the melting time and the maximum temperature of the bottom section of the structure. The outcomes from the present work are helpful to quantify the effects of porosity and anisotropy ratio on the thermal performance of the metal foam/PCM composite.