A new model for density of nanofluids including nanolayer

Abstract

Nanofluids which are suspension of nanoparticles in conventional heat transfer fluids attracted researchers while they show higher thermal conductivity and specific heat capacity. The important parameters have influence on thermal-fluid properties of nanofluids include the volume fraction of the nanoparticles, temperature, density of fluid base and nanoparticles, nanoparticles size, nanolayer, thermal conductivity of base fluid and particles, and pH. Nanolayer which is an approved interfacial layer between particles and base fluid involved in some of modelling for effective thermal conductivity and effective viscosity of nanofluids. Therefore, this layer must effect on other properties of nanofluids such as density. In this study investigation into the density of nanofluids has done experimentally.The nanofluids were investigated for density measurements consist of SiO2-Water, MgOGlycerol, CuO-Glycerol and SiOx-Ethylene Glycol /Water for range of 1 to 6% volume fraction as well as temperature range of 10 to 40 o C. The results show that mixture model for density of nanofluids (density of nanofluid = density of base fluid multiply by volume fraction of base fluid + density of nanoparticles multiply by volume fraction of nanoparticles) which is generally cited in literature has higher value than experimental data.For higher volume fraction of nanoparticles, the gap between the experimental results and the mixture model gets more. This is due to the nanolayer which also shows nanolayer density can be between void and the base fluid density. Therefore, based on the experimental data a new model for density of nanofluids developed which includes nanolayer. It was also found that the amount of the void in the nanolayer is more sensitive to nanoparticle size and not to base fluids or nanoparticles material.

A Review on Nanofluids: Fabrication, Stability, and Thermophysical Properties

“…There are limited number of correlations available, for the effective density of nanofluid, that takes into account the particle size and shape, nanofluid temperature, added surfactant, and the nanolayer between the particles and the basefluid effect [213,214]. Hence more work is needed in this area to insure a much accurate prediction of the effective density at higher particles concentrations.…”

Experimental Research and Development on the Natural Convection of Suspensions of Nanoparticles—A Comprehensive Review

“…Density relates directly to the Nusselt number ( Nu ), Reynolds number ( Re ), pressure drop and friction factor of NF in CNT. Experimental measurements of the densities of NF and HNF have been carried out using different base fluids and NP or HNP at various temperatures and volume/mass concentrations or fractions [ 22 , 33 , 47 , 73 , 117 , 123 , 124 , 125 , 126 , 127 , 128 ]. The literature showed that the density of NF and HNF enhanced with the dispersion of NP or HNP in the different base fluids and detracted with a rise in temperature.…”

Exploration of nanofluid pool boiling and deposition on a horizontal cylinder in Eulerian and Lagrangian frames

“…Therefore, updated mixture properties are required to be implemented. The mixture correlation is borrowed from the model developed by Sharifpur et al [49].…”