Buoyancy driven convection in open-cell metal foam using the volume averaging theory

•Heat sinks with metal foam are studied in buoyancy driven convection.•Study is done numerically based on VAT and comparison is made with experiments.•When only convection is taken into account: differences are smaller than 29%.•When radiative heat transfer is included: differences are smaller than 9%.•Sensitivity study shows that convection coefficient is not most important parameter.

Heat sinks with open-cell aluminium foam are studied numerically in buoyancy driven convection with air as surrounding medium. Results from a 2D numerical model are compared to experiments for different foam heights. The numerical model is based on the volume averaging theory. If only convective heat transfer is taken into account in the numerical model, the relative differences between the numerical and experimental results are smaller than 29% for all foam heights studied. However, when the influence of radiation is included in the numerical model, it is shown that the numerical results differ less than 9% with the experimental ones. This clearly shows that it is necessary to properly model radiative heat transfer in numerical models of open-cell aluminium foam in buoyancy driven convection.Finally, a sensitivity study of ten main parameters of the volume averaged model (closure terms, effective properties) and the experimental setup (substrate temperature, dimensions of the heat sink) is performed. It is shown that the construction details and dimensions of the experimental setup have the largest impact on the heat transfer rate and not the convection coefficient, as is often assumed.