Experimental study on the thermal conductivity of graphene–carbon nanotube–silver nanoparticle ternary hybrid nanofluids

Abstract

In this study, high-thermal-conductivity ternary hybrid nanofluids incorporating graphene–carbon nanotube–silver (Gr–CNT–AgNP) hybrid materials were successfully prepared. The influence of nanoparticle concentration (0–0.05 vol%) and operating temperature (30–55 °C) on the thermal conductivity of both water-based and ethylene-glycol (EG)-based nanofluids was systematically examined. The thermal conductivity increased monotonically with Gr–CNT–AgNP loading, achieving maximum enhancements of 38% for water-based and 52% for EG-based nanofluids at 0.05 vol% and 55 °C. Quantitative analysis showed that concentration contributed more strongly to conductivity improvement than temperature, though temperature-induced intensification of Brownian motion provided an additional enhancement of up to ∼10% across the tested range. A predictive thermal conductivity model was also developed, yielding an excellent fit to experimental data with deviations below 5%, thereby validating its accuracy and applicability. Overall, the Gr–CNT–AgNP ternary hybrid nanofluids demonstrate substantial potential for high-performance thermal management systems, including cooling, heat-transfer devices, and solar-thermal collectors.