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

Sushrut Sandeep Bhanushali, Naveen Noah Jason, Prakash Ghosh, Anuradda Ganesh, George Philip Simon, Wenlong Cheng

Research output: Contribution to journalArticleResearchpeer-review

Abstract

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, 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.

Original languageEnglish
Pages (from-to)18925-18935
Number of pages11
JournalACS Applied Materials and Interfaces
Volume9
Issue number22
DOIs
Publication statusPublished - 7 Jun 2017

Keywords

  • aspect ratio
  • copper nanocubes
  • copper nanowires
  • nanofluids
  • thermal conductivity

Cite this

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title = "Enhanced Thermal Conductivity of Copper Nanofluids: The Effect of Filler Geometry",
abstract = "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, 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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Enhanced Thermal Conductivity of Copper Nanofluids : The Effect of Filler Geometry. / Bhanushali, Sushrut Sandeep; Jason, Naveen Noah; Ghosh, Prakash; Ganesh, Anuradda; Simon, George Philip; Cheng, Wenlong.

In: ACS Applied Materials and Interfaces, Vol. 9, No. 22, 07.06.2017, p. 18925-18935.

Research output: Contribution to journalArticleResearchpeer-review

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