The effects of topology upon fluid-flow and heat-transfer within cellular copper structures

The fluid-flow and heat-transfer features of cellular metal lattice structures made from copper by transient liquid phase (TLP) bonding and brazing of plane weave copper meshes (screens) were experimentally characterized under steady-state forced air convection. Due to the inherent structural anisotropy of this metal textile derived structure, the characterizations were performed for several configurations to identify the preferable orientation for maximizing thermal performance as a heat dissipation medium. Results show that the friction factor of bonded wire screens is not simply a function of porosity as stochastic materials such as open-celled metal foams and packed beds, but also a function of orientation (open area ratio). The overall heat transfer depends on porosity and surface area density, but only weakly on orientation. Comparisons with stochastic metal foams and other heat dissipation media such as packed beds, louvered fins and microtruss lattice cellular materials suggest that wire-screen meshes compete favorably with the best available heat dissipation media. The overall thermal efficiency index of the copper textiles-based media is approximately three times larger than that of stochastic copper foams, principally because of the lower pressure drop encountered during coolant propagation through the periodic wire-screen structure. (C) 2004 Elsevier Ltd. All rights reserved.