Decoupled Thermal and Fluidic Effects on Hotspot Cooling in a Boiling Flow Microchannel Heat Sink

Heat sinks for next generation microprocessors must remove increasing levels of power with non-uniform spatial distribution (hotspots). Two-phase convection promises strongly reduced pump size but is challenging because of boiling flow instabilities. This work studies parallel microchannel boiling stability using a series of dual channel devices which are fabricated with varying lateral thermal resistance and integrated heaters and thermometers. The data are consistent with a demand curve analysis predicting flow distribution and wall temperatures in thermally isolated parallel channels with strictly fluidic interaction. Increasing the thermal resistance between two parallel channels is shown to strongly influence the onset of instabilities and adversely increase the peak temperature. These dual-channel experiments capture the key physics of multichannel instabilities and provide the foundation for improved design of two-phase microfluidic heat sinks.