Flow boiling heat transfer and pressure drop characteristics in expanding silicon microgap heat sink

The present flow boiling experiments are performed for deionized water mass fluxes, G = 400-1000 kg/m2 s, imposed effective heat flux qeff″ ranging from 0 W/cm2 to 80 W/cm2 for three different microgap configurations having same inlet depth 200 μm and gradually increasing exit depth 200 μm, 300 μm and 460 μm to explore expanding microgap effect on heat transfer and pressure drop performances. High speed flow visualizations are conducted simultaneously along with experiments to explore the bubble behavior in expanding microgap heat sink. The results of this study show that expanding microgap maintains a more uniform wall temperature than straight microgap heat sink and also delays dryout phase. In addition, expanding microgap of exit depth 300 μm performs best for both heat transfer and pressure drop performances among all configurations.