Microfluidic one-step production of zinc oxide nanofluids for enhanced phase change heat transfer in electronics

Nanofluids offer significant potential for enhancing heat transfer compared to conventional working fluids. However, the continuous, high-throughput synthesis of ZnO nanofluids with uniform dispersion and long-term stability remains challenging. Herein, a one-step microfluidic strategy is presented which leverages Dean vortices to intensify fluid mixing, enabling the continuous production of ZnO nanofluids with superior ambient stability. Subsequent flow boiling experiments reveal substantial enhancements in CHF and HTC. Optimal performance is achieved using a 0.001 wt% ZnO nanofluid at a flow velocity of 0.3 m s⁻¹, yielding maximum CHF and HTC increases of 36.7% and 41.5%, respectively, alongside a 9.9 °C reduction in wall temperature. Surface characterizations demonstrate that nanoparticle deposition is fundamentally responsible for these thermal improvements. Conversely, excessive nanoparticle concentrations produce thicker deposits that increase interfacial thermal resistance, consequently degrading the heat transfer performance. Statistical analysis of bubble dynamics further corroborates these underlying mechanisms. Ultimately, these insights provide quantitative guidelines for the scalable synthesis of nanomaterials and advance the deployment of surface-engineered nanofluids in high-power electronic thermal management.