Pore-scale simulation of forced convection heat transfer in metal foams with uniform and gradient structures

Abstract

Because of their large specific surface areas, metal foams are commonly used in studies of enhanced heat transfer. Modified metal foams with gradient structures are often chosen to reduce high pressure drop. Using computational fluid dynamics (CFD), forced convective heat transfer of metal foam samples for uniform and gradient structures with the same porosity and pore per inch (PPI) were investigated. To study the effect of gradient porosity under the premise of constant control porosity. First, heat transfer was examined in relation to gradient orientation. Gradient metal foam showed a 27.25% improvement in overall heat transfer performance when using the arrangement from small to large porosity than in the opposite direction. In addition, their performance was compared with that of uniform metal foam with 10 PPI and 0.88 porosity. The results showed that for 0.88 porosity, the gradient structure reduced the pressure drop by 23.66% and improved the overall heat transfer performance by 12.07% relative to the uniform structure. The gradient structure was better than the uniform structure at a given porosity value. The sudden change in geometry at the gradient interface of a gradient structure caused changes in flow and heat transfer compared to a uniform structure.