Forced convection air cooling in porous graphite foam for thermal management applications

Rapid development in the design of electronic packages for modern high-speed computers has led to the demand for effective methods of chip cooling. The primary concerns in thermal management applications are high thermal conductivity, large specific surface area and low weight. Graphite foams which possess predominantly spherical pores with smaller openings between the cells constitute a novel highly-conductive porous material for electronic cooling applications. These foams can be produced with bulk thermal conductivities almost equivalent to dense aluminum alloys with only 1/5 the weight of solid aluminum material. Motivated by the thermal and physical properties of graphite foam, experiments were performed to assess the cooling performance of such foams for thermal management applications. A test facility was developed for experimental studies under constant heat flux heating condition. The graphite foam heat sinks were fabricated into different structures, which were designed to utilize the porous properties of the foam for heat removal. Heat transfer characteristics including local temperature and Nusselt number distributions for steady flow through the tested heat sinks were measured and a correlation of length-averaged Nusselt number in terms of Prandtl and Reynolds numbers was obtained. The findings of this study show that graphite foam heat sinks with appropriate structure can offer good heat removal with relatively low pressure drop.