Abstract

A comparative study, for the first time, was conducted on thermophysical and rheological properties of single-walled carbon nanotubes (SWCNT) and graphene nanoplatelets (GNP) nanofluids. Highly stable aqueous 0.5, 1.0, and 2.0 wt% SWCNT and GNP nanofluids were successfully prepared with no surfactant, through ultrasound technology. The preparation was explained in detail, adjusting pH to around 8 where nanofluids would be expected to be stable. The highest zeta potential of −60.5 mV was obtained for 2.0 wt% SWCNT nanofluids. Shear thinning was observed for all nanofluids at low shear rates. Unlike shear thickening of GNP, Newtonian behavior of SWCNT nanofluids was detected at high shear rate region. The effect of ultrasound technology was directly verified by scanning electron microscopy (SEM), resulting in GNP size reduction and separation of bundles for SWCNT. The results revealed that SWCNT nanofluids showed a remarkable zeta potential value for heat transfer systems compared to GNP nanofluids.

摘要

首次对单壁碳纳米管（SWCNT）和石墨烯纳米片（GNP）纳米流体的热物理和流变特性进行了比较研究。通过超声波技术，在没有表面活性剂的情况下成功制备了高度稳定的含水 0.5、1.0 和 2.0 wt% SWCNT 和 GNP 纳米流体。详细解释了制备过程，将 pH 值调整到 8 左右，纳米流体有望保持稳定。对于 2.0 wt% SWCNT 纳米流体，获得了 -60.5 mV 的最高 zeta 电位。在低剪切速率下观察到所有纳米流体的剪切稀化。与 GNP 的剪切增稠不同，在高剪切速率区域检测到 SWCNT 纳米流体的牛顿行为。超声技术的效果直接通过扫描电子显微镜（SEM）验证，导致 GNP 尺寸减小和 SWCNT 束分离。结果表明，与 GNP 纳米流体相比，SWCNT 纳米流体对于传热系统显示出显着的 zeta 电位值。