Viscosity and thermal conductivity of nanofluids containing multi-walled carbon nanotubes stabilized by chitosan

    Authors

    T. X. Phuoc; M. Massoudi;R. H. Chen

    Comments

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    Abbreviated Journal Title

    Int. J. Therm. Sci.

    Keywords

    MWCNT nanofluids; Thermal conductivity; Viscosity; Stability; PARTICLE CONCENTRATION; 2ND-GRADE FLUID; HEAT-TRANSFER; SUSPENSIONS; MODEL; FLOW; THERMODYNAMICS; NANOPARTICLES; ENHANCEMENT; SURFACTANT; Thermodynamics; Engineering, Mechanical

    Abstract

    Thermal conductivity, viscosity, and stability of nanofluids containing multi-walled carbon nanotubes (MWCNTs) stabilized by cationic chitosan were studied. Chitosan with weight fraction of 0.1%, 0.2 wt%, and 0.5 wt% was used to disperse stably MWCNTs in water. The measured thermal conductivity showed an enhancement from 2.3% to 13% for nanofluids that contained from 0.5 wt% to 3 wt% MWCNTs (0.24 to 1.43 vol %). These values are significantly higher than those predicted using the Maxwell's theory. We also observed that the enhancements were independent of the base fluid viscosity. Thus, use of microconvection effect to explain the anomalous thermal conductivity enhancement should be reconsidered. MWCNTs can be used either to enhance or reduce the fluid base viscosity depending on the weight fractions. In the viscosity-reduction case, a reduction up to 20% was measured by this work. In the viscosity-enhancement case, the fluid behaved as a non-Newtonian shear-thinning fluid. By assuming that MWCNT nanofluids behave as a generalized second grade fluid where the viscosity coefficient depends upon the rate of deformation, a theoretical model has been developed. The model was found to describe the fluid behavior very well. Published by Elsevier Masson SAS.

    Journal Title

    International Journal of Thermal Sciences

    Volume

    50

    Issue/Number

    1

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    12

    Last Page

    18

    WOS Identifier

    WOS:000286123400003

    ISSN

    1290-0729

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