REDUCED PUMPING POWER AND WALL TEMPERATURE IN MICROCHANNEL HEAT SINKS WITH FRACTAL-LIKE BRANCHING CHANNEL NETWORKS

Abstract

Comparisons are made of the maximum channel wall temperature along, and total pressure drop across, a heat sink with a fractal-like branching channel network with those in a heat sink having a straight channel array. The total channel lengths are identical between the heat sinks, as are the applied heat fluxes. The hydraulic diameter of the straight channel array is equal to that of the terminal branch of the branching channel network. The number of branches per level, number of branching levels, and channel dimensions in the fractal-like network remain fixed. Minor losses are neglected and both hydrodynamic and thermal boundary layers are assumed to reinitiate following each channel bifurcation in the branching flow network. With identical total convective surface areas for both configurations and maintaining a heat sink surface area equal to that of the convective surface area, the fractal-like channel network yielded a 60% lower pressure drop for the same total flow rate and a 30°C lower wall temperature under identical pumping power conditions. The two heat sinks were also compared under identical pressure drop conditions. Channel packing densities in which the convective surface area in the fractal-like channel network is 50% less than that in the straight channel array yield approximately the same pressure drop and maximum wall temperature for fixed-flow-rate conditions.