Thermal Dispersion in Metal Foams

Open-cell metal foams are of interest for a variety of thermal engineering applications because of their high surface-to-volume ratio and high convective heat transfer coefficients relative to conventional fins. The tortuous flow path through the foam promotes rapid transverse mixing, a fact that is important in heat exchanger applications. Transverse mixing acts to spread heat away from a heated surface, bringing cooler fluid to the foam elements that are in direct contact with the surface. Heat is also spread by conduction in the foam ligaments. The present work addresses fully-coupled thermal dispersion in a metal foam. Dispersion of the thermal wake of a line source was measured. A conjugate heat transfer model was developed which showed good agreement with the data. The validated model was used to examine the complementary effects of the mechanical dispersion, molecular diffusion in the gas, and conduction in the solid.