Suppressing Density-Wave Oscillation during Dielectric-Fluid Flow Boiling Using Nanowires

Thermal management of high-heat-flux electronic devices via two-phase flow in microchannels holds significant potential; however, flow instabilities remain a major challenge. Pressure-drop and flow-rate oscillations can induce thermal and mechanical fatigue, adversely affecting the reliability of the system. Extensive research has explored micro- and nanoscale surface morphologies in microchannels to address thermofluid instabilities in flow boiling with water as the working fluid. A detailed understanding of the effects of surface structures on flow instabilities using industry-relevant dielectric fluids is still needed. Our findings highlight the ability of the nanowire microchannel to suppress density-wave oscillations while enhancing the heat-transfer coefficient for the Opteon SF33 fluid. The nanowire surface effectively reduces the amplitude and frequency of mass-flux and pressure-drop oscillations, even under high-heat-flux conditions near the critical heat flux. This improvement is attributed to the superior wettability of the nanowire surface, which promotes stable annular flow and maintains consistent frictional pressure, thereby suppressing oscillations in pressure drop.