After a review of the history and an assessment of the current status of the subject, we present light-scattering data to determine the critical correlation-function exponents for an aqueous electrolyte solution yielding the experimental values γ=1.238±0.012, ν=0.629±0.003, η=0.032±0.013. We conclude the paper with some comments concerning the temperature dependence of non-asymptotic effective critical-exponent values of fluids.

Experimental Critical-Exponent Values for Fluids

In transport phenomena, precise knowledge or estimation of fluids properties is necessary, for mass flow and heat transfer computations. Viscosity is one of the important properties which are affected by pressure and temperature. In the present work, based on statistical techniques for nonlinear regression analysis and correlation tests, we propose a novel equation modeling the relationship between the two parameters of viscosity Arrhenius-type equation, such as the energy () and the preexponential factor (). Then, we introduce a third parameter, the Arrhenius temperature (), to enrich the model and the discussion. Empirical validations using 75 data sets of viscosity of pure solvents studied at different temperature ranges are provided from previous works in the literature and give excellent statistical correlations, thus allowing us to rewrite the Arrhenius equation using a single parameter instead of two. In addition, the suggested model is very beneficial for engineering data since it would permit estimating the missing parameter value, if a well-established estimate of the other parameter is readily available.

https://downloads.hindawi.com/journals/jchem/2015/163262.pdf

A New Equation Relating the Viscosity Arrhenius Temperature and the Activation Energy for Some Newtonian Classical Solvents

We report definitive evidence for an effective interfacial tension between two types of miscible fluids using spinning-drop tensiometry (SDT). Isobutyric acid (IBA) and water have an upper critical solution temperature (UCST) of 26.3 °C. We created a drop of the IBA-rich phase in the water-rich phase below the UCST and then increased the temperature above it. Long after the fluids have reached thermal equilibrium, the drop persists. By plotting the inverse of the drop radius cubed (r-3) vs the rotation rate squared (ω2), we confirmed that an interfacial tension exists and estimated its value. The transition between the miscible fluids remained sharp instead of becoming more diffuse, and the drop volume decreased with time. We observed droplet breakup via the Rayleigh−Tomotika instability above the UCST when the rotation rate was decreased by 80%, again demonstrating the existence of an effective interfacial tension. When pure IBA was injected into water above the UCST, drops formed inside the main drop ev...

Evidence for the Existence of an Effective Interfacial Tension between Miscible Fluids: Isobutyric Acid−Water and 1-Butanol−Water in a Spinning-Drop Tensiometer

Heavy and extra-heavy oils generally exhibit high viscosity, which is detrimental to their production, transport, and refining. The oil and gas industry has thoroughly investigated the use of chemical agents to improve the mobility of this type of low-quality crude oil at the surface as well as reservoir conditions for many years. In this sense, the main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s–1. Upon addition of nanoparticles, viscosity reduction was observed in all cases evaluated. However, the maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/L with 7 nm SiO2 nanoparticles at shea...

Experimental and Theoretical Study of Viscosity Reduction in Heavy Crude Oils by Addition of Nanoparticles

Contribution to modeling the viscosity Arrhenius-type equation for some solvents by statistical correlations analysis

Effect of ion impurities on a binary mixture of isobutyric acid and water

Volumetric and refractive index properties of isobutyric acid — water binary mixtures at temperatures ranging from 300.15 to 313.15 K

Coexistence curves of the binary mixture isobutyric acid–water with added ions (K+,Cl−)

The excess molar volume VE, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures, both near and close to the critical temperature (2.055K ≤ (T−Tc)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values of VE and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters ΔH∗ and ΔS∗ have been also calculated and show that the critical region has an important effect on the volumetric properties.

Excess molar volume and viscosity of isobutyric acid + water binary mixtures near and far away from the critical temperature

Kinematic viscosities and densities of in aqueous solutions, from pure water to very concentrated solutions, were determined at different temperatures. Shear viscosity data for this asymmetrical 3:1 electrolyte were calculated. For the low concentrations , the Jones - Dole coefficients A and B were determined for this rare-earth salt by fitting the quadratic behaviour of the square root of the molar concentration with the least-squares method. At concentrations above 1 mol , the logarithm of viscosity can be fitted by a third-order polynomial, where the coefficients exhibit a linear dependence on the reciprocal of the absolute temperature. This phenomenon is due to the strong ion - solvent correlation.

M. Bouanz

Papers

Effect of ion impurities on a binary mixture of isobutyric acid and water

Volumetric and refractive index properties of isobutyric acid — water binary mixtures at temperatures ranging from 300.15 to 313.15 K

Coexistence curves of the binary mixture isobutyric acid–water with added ions (K+,Cl−)

Excess molar volume and viscosity of isobutyric acid + water binary mixtures near and far away from the critical temperature

A shear viscosity study of cerium (III) nitrate in concentrated aqueous solutions at different temperatures