Comparative analysis of flow behavior during the nanofluid Phase transition at serpentine microchannel bends

Abstract

With the growing demand for high-flux thermal management in electronics, understanding nanofluid flow dynamics during phase transitions in complex microchannel geometries remains a critical yet underexplored frontier. This study pioneers a comprehensive investigation into the flow characteristics of four nanofluids (Cu-water, Al₂O₃-water, Al-water, SiO₂-water) before and after liquid-vapor phase transitions in serpentine microchannel bends, integrating the Mixture model with the RNG k-ε turbulence model. The novelty lies in the coupled analysis of multiphase flow, flow behavior and geometric effects during the phase transition of nanoparticles at different Reynolds numbers (100–400), volume fractions (0.1 %–1.3 %) and heat fluxes (50–80kW/m²). Key findings reveal that the change of heat flux density in pre-phase transition has little effect on pressure drop, but escalates with Reynolds number and volume fraction, with Cu-water exhibiting the highest growth rates (66.91 % and 42.96 %, respectively). Post-phase transition, despite lower absolute pressure drops, growth rates surpass pre-transition values (Cu-water: 67.16 % and 43.15 %), driven by vapor-induced turbulence and altered flow resistance mechanisms. These insights challenge the traditional single-phase cooling paradigm by quantifying how phase transitions modulate the behavior of nanofluids within serpentine microchannels, and can provide theoretical references for fields such as high-power electronics and aerospace thermal management.