Thermal conductivity of dry anatase and rutile nano-powders and ethylene and propylene glycol-based TiO2 nanofluids

https://doi.org/10.1016/j.jct.2014.12.001Get rights and content

Highlights

Abstract

Thermal conductivity behaviour was studied for two TiO2 nano-powders with different nanocrystalline structures, viz. anatase and rutile, as well as nanofluids formulated as dispersions of these two oxides up to volume concentrations of 8.5% in two different glycols, viz. ethylene and propylene glycol. Because it is known that titanium dioxide can exhibit three different crystalline structures, the dry nano-powders were analysed using X-ray Diffraction to determine the nanocrystalline structure of the powders. Two different techniques were employed in the thermal conductivity study of the materials. Dry nano-powders, with and without compaction, were analysed at room temperature by using a device based on the guarded heat flow meter method. Nanofluids and base fluids were studied with a transient hot wire technique over the temperature range from (283.15 to 343.15) K. The base fluid propylene glycol was measured by using both techniques in order to verify the good agreement between both sets of results. The experimental measurements presented in this work were compared with other literature data for TiO2 nanofluids in order to understand the thermal conductivity enhancement as a function of nanoparticle concentration. Different theoretical or semi-theoretical approaches such as Maxwell, Peñas et al., Yu-Choi were evaluated comparing with our experimental values. A parallel model was used to predict thermal conductivities employing experimental values for dry nanopowder.

Section snippets

Introduction and background

The increasing demand for device miniaturisation as well as higher awareness on thermal energy consumption leads to the need of improving material heat transfer properties. The storage of thermal energy in the form of sensible and latent heat has become an important aspect of energy management with the emphasis on efficient use and conservation of waste heat and renewable energy in industry and buildings [1], [2]. In this task, thermal fluids like water, glycols or engine oils are commonly used

Materials, characterisation and sample preparation

Two TiO2 nano-powders from SkySpring Nanomaterials (Inc. Houston, TX, USA) and mass purities of 99.5% were used in this work. According to supplier, the first sample corresponds to a pure anatase monocrystalline phase with a declared diameter distribution of d = (10 to 30) nm while the second corresponds to a pure rutile phase with d = (10 to 25) nm. The base fluids, ethylene glycol and propylene glycol, were supplied by Sigma–Aldrich (St. Louis, MO, USA) with mass purities of 99.5%. All products

Titanium oxide nano-powders

As pointed above, in order to evaluate (particle + particle) interface thermal resistance in addition to the thermal resistance of nanoparticles, we have measured the thermal conductivity of solid titanium oxide nano-powders. These measurements were performed using nano-powders in both compacted and non-compacted forms. The obtained thermal conductivity data are presented in table 2 together with the volume fractions of the solid nanoparticles, which are calculated as the ratio of experimental

Conclusions

An experimental thermal conductivity study has been performed for two dry nanocrystalline structures of TiO2, anatase and a mixture of anatase and rutile, and for nanofluids formulated by using these oxides and two base fluids, ethylene and propylene glycol. The thermal conductivities for dry samples fall within the range (0.42 to 0.61) W · m−1 · K−1 giving account of the thermal resistance in the nanoparticle, but also of the (particle + particle) interface thermal resistance, which has been scarcely

Acknowledgements

This work was supported by the “Ministerio de Economía y Competitividad” (Spain) and the FEDER program through the Project ENE2012-32908. The authors also acknowledge the financial support from Fundación Iberdrola and Universidade de Vigo. D.C. and L.L. acknowledge the financial support under the FPU and Ramón y Cajal program provided by the “Ministerio de Educación, Cultura y Deporte”, and “Ministerio de Ciencia e Innovación” (Spain), respectively. M.J.P.-G. acknowledges the financial support

References (76)

  • Y. He et al.

    Int. J. Heat Mass Transfer

    (2007)
  • Z. Haddad et al.

    Int. J. Therm. Sci.

    (2014)
  • C. Hu et al.

    Mater. Lett.

    (2010)
  • L. Fedele et al.

    Int. J. Refrig.

    (2012)
  • S. Ponmani et al.

    Colloids Surf. A

    (2014)
  • S. Witharana et al.

    Powder Technol.

    (2013)
  • M.C.S. Reddy et al.

    Int. Commun. Heat Mass

    (2013)
  • T. Yiamsawasd et al.

    Thermochim. Acta

    (2012)
  • G.A. Longo et al.

    Exp. Therm. Fluid Sci.

    (2011)
  • S.M.S. Murshed et al.

    Int. J. Therm. Sci.

    (2005)
  • R. Saleh et al.

    Exp. Therm. Fluid Sci.

    (2014)
  • D.H. Yoo et al.

    Thermochim. Acta

    (2007)
  • A.M.A. Adam

    Spectrochim. Acta A

    (2014)
  • P. Pathak et al.

    Radiat. Phys. Chem.

    (2014)
  • D. Wen et al.

    Int. J. Heat Fluid Flow

    (2005)
  • U. Diebold

    Surf. Sci. Rep.

    (2003)
  • D. Cabaleiro et al.

    J. Chem. Thermodyn.

    (2013)
  • G. Paul et al.

    Renew. Sustainable Energy Rev.

    (2010)
  • C.A. Nieto De Castro et al.

    Int. J. Therm. Sci.

    (2012)
  • D. Cabaleiro et al.

    J. Chem. Thermodyn.

    (2012)
  • M.J. Pastoriza-Gallego et al.

    J. Chem. Thermodyn.

    (2014)
  • M.P. Beck et al.

    Fluid Phase Equilib.

    (2007)
  • J. Seo et al.

    Sens. Actuators B

    (2006)
  • A. Rawson et al.

    Int. J. Heat Mass Transfer

    (2014)
  • J. Wang et al.

    Int. J. Heat Mass Transfer

    (2006)
  • S. Kakaç et al.

    Int. J. Heat Mass Transfer

    (2009)
  • M.F. Demirbas

    Energy Source B

    (2006)
  • W. Yu et al.

    J. Nanomater.

    (2012)
  • S.U.S. Choi, Enhancing thermal conductivity of fluids with nanoparticles, American Society of Mechanical Engineers,...
  • I. Palabiyik et al.

    J. Nanopart. Res.

    (2011)
  • V.H. Grassian et al.

    Environ. Health Perspect.

    (2007)
  • D. Reyes-Coronado et al.

    Nanotechnology

    (2008)
  • D. Cabaleiro et al.

    Nanoscale Res. Lett.

    (2013)
  • Y. Hu et al.

    J. Heat Transfer

    (2014)
  • S.S. Sonawane et al.

    J. Exp. Nanosci.

    (2013)
  • Z.L. Wang et al.

    Int. J. Thermophys.

    (2007)
  • E.V. Timofeeva et al.

    Phys. Rev. E

    (2007)
  • S.H. Kim et al.

    J. Heat Transfer

    (2007)
  • Cited by (92)

    • Thermophysical, rheological and electrical properties of mono and hybrid TiB<inf>2</inf>/B<inf>4</inf>C nanofluids based on a propylene glycol:water mixture

      2022, Powder Technology
      Citation Excerpt :

      Then, each sample disk is placed between the heat source located on the top plate and the heatsink located below the bottom plate, and a steady heat flow is established between them. The expanded uncertainty of the assessed thermal conductivity values is declared as 6% [27]. The density (ρ) of the nanofluids and the base fluid was determined in a temperature range of 288.15–318.15 K using a DMA 4100 M density meter (Anton Paar, Austria).

    View all citing articles on Scopus
    View full text