Enhanced Thermal Conductivity of Copper Nanofluids: The Effect of Filler Geometry

Nanofluids are colloidal dispersions that exhibit enhanced thermal conductivity at low filler loadings and thus have been proposed for heat :transfer applications. Here, we systematically investigate how particle shape determines the thermal conductivity of low-cost copper nanofluids using a range of distinct filler particle shapes: nanospheres, nanoculies short nanowires, and long nanowires. To exclude the potential effects of surface capping, ligands, all the filler particles are kept with uniform Surface chemistry. We find that,copper nanowires enhanced the conductivity up to 40% at 0.25 vol % loadings; while the thermal conductivity was only 9.3% and 4.2% for the nanosphere nanocube-based nanofluids, respectively, at the same filler loading. This is consistent with a porcolation mechanism in which a higher aspect ratio is beneficial for thermal conductivity enhancement. To overcome the,Surface oxidation of the. copper nanomaterials and maintain the dispersion stability, we employed,polyvinylpyrrolidone:(INP) as a dispersant and ascorbic acid as an antioxidant in the nanofluid formulations.. The thermal performance of the optimized fluid formulations could, be sustained for multiple heating-cooling cycles While tetaining stability over. 1000