Experimental Analysis on Flow and Heat Transfer Characteristics of Hybrid Nanofluids in Microchannels

Al₂O₃-TiO₂ hybrid nanofluids based on DI-water with particle volume fraction from 0.1% to 0.4% were prepared by the two-step methods. The appropriate surfactant was added to ensure the stability of hybrid nanofluids, and a thermal property analyzer (Hot-Disk 2500S) was used to measure the thermal conductivity of hybrid nanofluids. The prepared hybrid nanofluids were used to flow through straight-line and broken-line microchannel heat sinks, and the effects of concentration, inlet temperature, Re and microchannel structure on the heat transfer performance of microchannels were studied. Results show that compared with the straight-line microchannels, the heat transfer performance of hybrid nanofluids in the broken line is more strengthened; the heat transfer coefficients of hybrid nanofluids increase with the increase of the inlet temperature, Re and nanoparticle volume fraction; when the inlet temperature is 30℃, and the volume flow is 30 mL/min, compared with deionized water, the convective heat transfer coefficient, comprehensive performance and pressure drop of the hybrid nanofluids with a volume fraction of 0.4% in the broken-line microchannel increase by 30.90%, 18.70%, and 6.48%, respectively.