Experimental and theoretical investigation on Nano-fluid surface tension

Effect of gamma-Al2O3 and MgO nanoparticle on surface tension of Tri Ethylene Glycol (TEG) was studied for different nanoparticle concentrations. Furthermore, the effect of nanoparticle size on the Nano-fluid surface tension was investigated. Results showed that surface tension increases for some particle concentrations and decreases for some others; in other words, a certain particle concentration could not be determined as the boundary for the increase or decrease of surface tension. Moreover, Sorbitan oleate was added to TEG solution to investigate the changes in surface tension that may occur due to the addition of surfactants. It is shown that by increasing surfactant concentration, Nano-fluid surface tension would decrease. The effect of nanoparticle size on surface tension was analyzed as well. Using experimental data, five empirical and thermodynamic-based models; i.e., Redlich-Kister (RK), Malanovsky-Marsh (MM), Jufu et al. (JBZ), Chunxi et al. (CWZ) and Santos et al. (SFF) were evaluated for surface tension estimation, and it was found that SFF method is the best method to correlate nano fluid surface tension in this study. (C) 2015 Elsevier B.V. All rights reserved.