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Experimental study on density, thermal conductivity, specific heat, and viscosity of water-ethylene glycol mixture dispersed with carbon nanotubes

Ganeshkumar Jayabalan (Department of Mechanical Engineering, MSEC, Kilakarai, Tamilnadu, India)
Kathirkaman Durai (Anna University, CEG Campus, Department of Mechanical Engineering, Chennai, India)
Raja Kandhaswamy (UCER Campus, Department of Mechanical Engineering, Ramanathapuram, Tamilnadu, India)
Kumaresan Vellisamy (Anna University, CEG Campus, Department of Mechanical Engineering, Chennai, India)
Velraj Ramalingam (Anna University, CEG Campus, Department of Mechanical Engineering, Chennai, India)

This article presents the effect of adding multi wall carbon nanotubes (MWCNT) in water – ethylene glycol mixture on density and various thermophysical properties such as thermal conductivity, specific heat and viscosity. Density of nanofluids was measured using standard volumetric flask method and the data showed a good agreement with the mixing theory. The maximum thermal conductivity enhancement of 11 % was noticed for the nanofluids with 0.9 wt. %. Due to lower specific heat of the MWCNT, the specific heat of the nanofluids decreased in proportion with the MWCNT concentration. The rheological analysis showed that the transition region from shear thinning to Newtonian extended to the higher shear stress range compared to that of base fluids. Viscosity ratio of the nanofluids augmented anomalously with respect to increase in temperature and about 2.25 fold increase was observed in the temperature range of 30 – 40 ˚C. The modified model of Maron and Pierce predicted the viscosity of the nanofluids with the inclusion of effect of aspect ratio of MWCNT and nanoparticle aggregates.

Keywords: carbon nanotube, nanofluid, thermal conductivity, rheology