Coupled conduction-convection heat transfer of non-Darcy flow in low-porosity open-cell Voronoi foams: a pore-scale study

Open-cell porous foams provide many applications in thermo-fluid problems. Typically, high-porosity metal foams are utilized in thermal applications. However, medium and low-porosity open-cell ceramic foams (porosity <70%) can retain thermal energy within their solid structure, providing a uniform temperature that can be used to improve reactive thermo-fluid problems. Nevertheless, systematic pore-scale investigations of low-porosity foams, particularly ceramic foams, remain limited. This study presents a direct pore-scale simulation to analyze non-Darcy fluid flow, coupled conduction-convection energy transfer in low-porosity open-cell porous foams. The finite volume method, based on the OpenFOAM open-source library, is used to solve the problem. A code is developed to generate open-cell foams (porosities of 54%, 62%, and 69% with a fixed pore density of 30 pores per inch (PPI)). The effects of porosity and foam material (copper, aluminum, and silicon carbide) on flow and heat transfer characteristics for various Reynolds numbers in both non-Darcy and Darcy conditions are investigated. The findings indicate that at a fixed pore density, decreasing porosity from 69.0% to 54.4% increases the streamwise pressure drop by 103.6% and 122.3% at Re p = 50 and 120, respectively. Conversely, convective performance declines with increasing porosity, such that the 54.4% foam on average provides 14.7%(22.1%) and 32.4%(47.1%) higher heat transfer coefficient than the 61.8% and 69.0% foams at Re p = 50( Re p = 120).