Hydrophobic surface-assisted SiO₂/DI-water nanofluids for enhancing heat transfer and reducing flow resistance

Nanofluids for heat transfer application suffer from inevitable pump power consumption and adhesion effect with interface during flow. The hydrophobic treatment for heat transfer surface may be one of the most prospective strategies to achieve heat transfer enhancement and flow resistance reduction. However, the limitations of hydrophobic treatment technique and process make it difficult to fabricate desirable large size and high curvature hydrophobic surface. Herein, a facile displacement reaction method is applied to prepare the lath-like silver crystals and micro-nano gaps in the inner surface of copper tube with assistance of benzoic acid dispersant. The result shows that the convective heat transfer coefficient increases to 18.1% and the Darcy friction factor decreases to 4.9% at the volume concentration of 2.0% when SiO₂/DI-water (deionized water) nanofluids flow through the hydrophobic surface. The hydrophobic surface-assisted strategy may provide an effective scheme for wide applications of nanofluids in heat exchange equipment.