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Experimental investigation on thermal and rheological properties of n-octadecane with dispersed TiO2 nanoparticles

In the present study, titanium(IV) oxide (TiO2) nanoparticles were dispersed in n-octadecane to fabricate phase

change material (PCM) with enhanced properties and behavior. Thermal conductivity (TC) and viscosity of

n-octadecane/TiO2 dispersions were experimentally investigated using transient plane source (TPS) technique

and rotating coaxial cylindrical viscometer, respectively. The results showed that the TC of n-octadecane/TiO2

dispersion depends on temperature and nanoparticle loading. A non-monotonic behavior of TC enhancement

in both solid and liquid phases was observed. In the solid phase, the maximum TC enhancement occurred at 3 wt.% of nanoparticles. When the nanoparticle mass fraction was over 4% in the liquid phase, the TC started to decrease. The rheological behavior of the n-octadecane/TiO2 samples indicated that dispersions with low nanoparticle mass fractions demonstrate Newtonian behavior, and for higher mass fractions the shear-thinning behavior was observed. Shear stress vs. shear rate curves showed that the liquid phase of PCMbehaves like a Bingham plastic fluid for mass fraction greater than 1%. As expected, the effective viscosity could be influenced by temperature. At the shear rate of 48.92 s−1 for 3 wt.% nanoparticles, the effective viscosity decreased by 26.8%while temperature increased from 35 °C to 55 °C. For the investigated n-octadecane/TiO2 dispersions, new thermophysical correlations are proposed for predicting TC and rheological properties.

http://www.sciencedirect.com/science/article/pii/S0735193314002516

Journal Papers
Month/Season: 
Fall
Year: 
2014

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