An experimental study on stability and thermal conductivity of water-graphene oxide/aluminum oxide nanoparticles as a cooling hybrid nanofluid

This experimental study investigated the thermal conductivity of the hybrid nanofluid of water-graphene oxide (GO) nanostructure/aluminum oxide (Al2O3) nanoparticles at a temperature range of 25-50 degrees C and volume fractions of 0.1, 0.25, 0.5, 0.75, and 1%. The quality of nanoparticles was ensured using XRD and SEM analysis. The volume fraction of nanoparticles in all experiments was 50%. The DLS test was then conducted to ensure nanofluid stability and determine the particle-size distribution (PSD) in the nanofluid. The thermal conductivity of the hybrid nanofluid was measured using the KD2 device at different temperatures and volume fractions. The results indicated that increasing the temperature from 25 to 50 degrees C and the volume fraction from 0.1% to 1% increased the thermal conductivity of the nanofluid up to 33.9%, with the former having a greater effect. Based on the results, compared to the base fluid, the largest improvement in thermal conductivity (33.9%) was achieved at the volume fraction of 1% and the temperature of 50 degrees C. Given that no accurate and proper relation exists for the prediction of thermal conductivity in this fluid, a relation was presented using mathematical modeling. The proposed relation was a function of volume fraction and temperature and was well consistent with the experimental results. (C) 2019 Elsevier Ltd. All rights reserved.