Improved thermal–hydraulic performance of a microchannel with hierarchical honeycomb porous ribs

Microchannel cooling technology has been proven to be extraordinarily efficient for the removal of heat flux in electronic devices. Here, we numerically investigate the thermal and hydraulic characteristics of microchannels with different shapes of ribs, namely, circular ribs, square ribs, regular ribs, and hierarchical honeycomb ribs. Those ribs are composed of solid and porous media. Results indicate that heat transfer can be promoted by adding different shapes of ribs. Especially, microchannels with hierarchical honeycomb ribs possess the greatest heat transfer capability. Pressure drop (Δp) and friction factor (f) display the largest values when microchannel ribs are hierarchical honeycomb and solid, whereas Δp of the microchannel with hierarchical honeycomb porous ribs dramatically decreases, which achieves an 81.1%–81.7% reduction. Results of j/f show that the microchannel with hierarchical honeycomb porous ribs presents the best comprehensive performance, which is ascribed to the superior heat transfer capability and the low Δp induced by the ultra-hydrophobic effect.