Experimental study on thermal properties and electrical conductivity of stabilized H2O-solar glycol mixture based multi-walled carbon nanotube nanofluids: developing a new correlation

The main aim of this present work is to explore the influence of dispersion of MWCNTs in a mixture of water-solar glycol (70:30) on its electrical conductivity and thermophysical properties such as density, rheology and thermal conductivity. The MWCNTs were seeded with a various weight percentage of 0.15, 0.3 and 0.45 via a common two-stage synthesis technique. The homogeneous stability of MWCNTs based nanofluids was confirmed by high-resolution scanning electron microscopy and ultraviolet-visible spectroscopy. The density of solar glycol and H2O mixture based MWCNTs nanofluids were measured with standard borosil volumetric flask via weighing balance mechanism and the experimental findings displayed a good agreement with the well-known correlation of Pak and Cho owing to the natural packing of H2O inside the nanomaterial in a limited quantity. The thermal conductivity of 0.45 wt. % MWCNTs seeding got augmented by 19.12% at ambient temperature while the electrical conductivity got augmented by 93.54% at 50 °C. Therefore, the augmentation in the thermal conductivity of water/solar glycol mixture with 0.45 wt. % MWCNTs seeding is because of the kinetics of nanomaterial accumulation and fluid layering. In addition, mathematical correlations were recommended for estimating the ratio of the thermal conductivity and viscosity of the nanofluid at different weight fractions.