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Enhanced Thermal Conductivity of Copper Nanofluids: The Effect of Filler Geometry
journal contribution
posted on 2017-05-04, 00:00 authored by Sushrut Bhanushali, Naveen Noah Jason, Prakash Ghosh, Anuradda Ganesh, George P Simon, Wenlong ChengNanofluids 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,
nanocubes, 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 thermal conductivity up to 40% at 0.25 vol % loadings; while the
thermal conductivity was only 9.3% and 4.2% for the nanosphere- and
nanocube-based nanofluids, respectively, at the same filler loading.
This is consistent with a percolation 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 (PVP) 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
retaining stability over 1000 h.
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copper nanofluidsconductivity enhancementcopper nanowires1000 hascorbic acidPVPsurface oxidationcopper nanomaterialsdispersion stabilityfiller loadingnanocube-based nanofluidsCopper Nanofluidsheat transfer applicationsnanosphereparticle shapeaspect ratiofiller loadingsfiller particlesuniform surface chemistrynanofluid formulationsFiller Geometry Nanofluidspercolation mechanismoptimized fluid formulationsfiller particle shapes
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