Journal of Materials Science

, Volume 52, Issue 5, pp 2642–2660

Thermophysical properties of paraffin-based electrically insulating nanofluids containing modified graphene oxide

  • Amir Hossein Aref
  • Ali Akbar Entezami
  • Hamid Erfan-Niya
  • Esmaeil Zaminpayma
Original Paper

DOI: 10.1007/s10853-016-0556-6

Cite this article as:
Aref, A.H., Entezami, A.A., Erfan-Niya, H. et al. J Mater Sci (2017) 52: 2642. doi:10.1007/s10853-016-0556-6
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Abstract

Electrically insulating nanofluids were prepared by dispersing modified graphene oxide nanosheets in an insulating medium (paraffin oil) by means of ultrasonication and without using any surfactant. Graphene oxide (GO) nanosheets were synthesized by an improved Hummers method. To improve the compatibility of the GO nanosheets with the oil, they were functionalized by treating with an alkylamine. After preparing the nanofluids, their properties such as thermal conductivity, viscosity and insulating properties were investigated experimentally at different concentrations. The results demonstrated that the thermal conductivity of the oil is enhanced with the addition of the nanosheets and increases with the increasing concentration. Comparison with other similar studies showed that at very low concentrations, the enhancement of thermal conductivity of nanofluids containing modified GO nanosheets is higher. Furthermore, rheological tests demonstrated that the viscosity of the nanofluids is lower in comparison with base oil, which can be considered as an advantage in terms of their thermal performance. Based on the experiments, it is found that the addition of the nanosheets leads to deterioration of the insulating properties of the oil, but available standards show that the prepared nanofluids are still suitable for use in industrial applications. The experimental results were also compared with the theoretical models. The results show that the Nan’s model gives better predictions of the thermal conductivity of these nanofluids in comparison with the classic model of Maxwell.

List of symbols

ks

The thermal conductivity of solid nanoparticles, W/m K

kbf

The thermal conductivity of base fluid, W/m K

knf

The thermal conductivity of nanofluid, W/m K

d

Interlayer distance, Å

lC

The length of the hydrocarbon chain of amine molecule, Å

n

Number of carbon atoms

Lii

Geometrical factor

Greek

ϕ

Particle volume fraction

θ

The hydrocarbon chain inclination

Subscripts

bf

Base fluid

nf

Nanofluid

s

Solid nanoparticles

Acronyms

GO

Graphene oxide

AGO

Alkylated graphene oxide

MWCNT

Multi-walled carbon nanotube

FEG-SEM

Field emission gun-scanning electron microscopy

FTIR

Fourier transform-infrared spectroscopy

EDX

Energy-dispersive X-ray analysis

XRD

X-ray diffraction

DMF

Dimethyl formamide

THW

Transient hot-wire technique

DF

Dissipation factor

IEC

International electrotechnical commission

Supplementary material

Supplementary material 1 (MPG 1842 kb)

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Amir Hossein Aref
    • 1
  • Ali Akbar Entezami
    • 2
  • Hamid Erfan-Niya
    • 1
  • Esmaeil Zaminpayma
    • 3
  1. 1.Department of Chemical and Petroleum EngineeringUniversity of TabrizTabrizIran
  2. 2.Laboratory of Polymer Chemistry, Faculty of ChemistryUniversity of TabrizTabrizIran
  3. 3.Physics Group, Qazvin BranchIslamic Azad UniversityQazvinIran

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