A Parameter for Selection of Nano-Dispersoids in Nanofluids for Thermal Applications

Abstract:

A model reported by the present investigators has earlier shown that the extent of heat pick up by a nanoparticle during its collision with the heat source in a given nanofluid would depend on the thermal conductivity (k_p, unit W/m.K), density (ρ, unit kg/m³), elastic modulus (E, unit GPa) and Poissons ratio (μ) of the nanoparticle and heat source. Considering the expression for collision period and thermal conductivity of nanoparticle, a factor χ =k_p(ρ/E)^0.4 is proposed here and examined for the preliminary identification of the potential of a dispersoid in enhancing the thermal conductivity of a nanofluid. The χ-factor for Ag, Cu, CuO, Al₂O₃ and SiO₂ are 2960, 2247, 116, 14.1 and 5.5, respectively. The higher χ-factor of CuO compared to that of Al₂O₃ can explain why water and ethylene glycol (EG) based CuO-nanofluid is reported to show higher enhancement in the thermal conductivity, when compared to similar Al₂O₃-nanofluid. The χ for SiO₂ is much smaller than that for Ag, which also corroborates well with the marginal enhancement in thermal conductivity of water based nanofluid containing SiO₂ nanoparticles. Therefore, a high value of χ of the nanodispersoid can serve as a parameter for the design of nanofluids for heat transfer applications.

• Periodical: Materials Science Forum (Volume 736)
• Pages: 223-228
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.736.223
• Online since: December 2012
• Authors: M.M. Ghosh, S. Ghosh, S.K. Pabi
• Keywords: Molecular Dynamic (MD), Nanofluid, Thermal Conductivity (TC)

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