Aqueous Mixtures with Nonpolar Gases at High Pressures and Supercritical Temperatures

1983 ◽  
Vol 22 ◽  
Author(s):  
E.U. Franck
Keyword(s):  
Dielectric Constant ◽  
High Pressures ◽  
Pure Water ◽  
Boundary Surface ◽  
Type Equation ◽  
Critical Curve ◽  
Aqueous Mixtures ◽  
Two Phase ◽  
Slow Increase ◽  
Critical Curves

ABSTRACTPTx-phase diagrams and critical curves for binary aqueous systems are briefly discussed. New results of the two-phase boundary surface and the critical curve for the water-nitrogen system to 2500 bar and 400°C are presented as isotherms in the Px-plane. A new extended Carnahan-Starling and squarewell type equation permits calculations of spinodal isopleths of the water-methane system and a prediction of the critical curve. - Excess volumes of supercritical benzene-water mixtures are given as functions of composition and pressure. Excess Gibbs energies and activity coefficients are derived. For the same system the static dielectric constant was measured between 300 and 400 °C in the homogeneous supercritical fluid for all concentrations. At 400 °C and 2000 bar the dielectric constant of pure water is 20 and decreases steeply with the addition of benzene. Addition of water to benzene causes at first only a slow increase above the value of 2 (for pure benzene). A short discussion of the description of the dielectric constant of such polar-nonpolar mixtures for wide ranges of density is given. - The solubility of anthracene in high density water to 250 °C was measured spectroscopically. Data are given. The “enhancement factor” is high at low temperature but decreases to unity at 250 °C and a water density of 1 g . cm−3

Critical Curves and Phase Equilibria of Binary Methanol-Systems for High Pressures and Temperatures

1995 ◽  
Vol 50 (4-5) ◽  
pp. 439-444 ◽  
Author(s):  
M. Neichel ◽  
E.U. Franck
Keyword(s):  
High Pressure ◽  
Binary Systems ◽  
High Pressures ◽  
Three Dimensional ◽  
Two Phase ◽  
Combination Rules ◽  
Critical Curves ◽  
Pressure Equilibrium ◽  
Square Well ◽  
High Pressures And Temperatures

Abstract The critical curves of binary systems of methanol combined with CH4, N2, H2, CO and CO2 have been determined experimentally up to 100 MPa and higher by Brunner. In the present work a rational equation of state of the perturbation type with a repulsion and an attraction term has been applied to reproduce these critical curves up to high pressures. A square well potential for intermolecular interaction is used. With pairwise combination rules for these potentials three adjustable parameters are needed. Values for these parameters, obtained from the fitting of the critical curves are used to calculate isotherms of the two-phase high pressure equilibrium surfaces for the four systems of methanol combined with CH4, N2, H2, and CO. Three of these have not yet been investigated experimentally. It is suggested to use this procedure for predictions of the extent of three-dimensional two-phase regions in temperature-pressure-composition spaces

Concept of Seafloor Mineral Processing for Development of Seafloor Massive Sulfides

2011 ◽  
Author(s):  
Yasuharu Nakajima ◽  
Shotaro Uto ◽  
Shigeo Kanada ◽  
Joji Yamamoto ◽  
Ichihiko Takahashi ◽  
...  
Keyword(s):  
High Pressures ◽  
Pure Water ◽  
Analytical Data ◽  
Mineral Resources ◽  
Mineral Processing ◽  
Column Flotation ◽  
Metallic Elements ◽  
Massive Sulfides ◽  
Chemical Reagents ◽  
Froth Layer

Seafloor Massive Sulfides (SMS), which were formed by deposition of precipitates from hydrothermal fluids vented from seafloor, is one of unconventional mineral resources beneath deep seafloors in the world. The authors have proposed the concept of seafloor mineral processing for development of SMS, where useful minerals included in SMS ores are separated on seafloor to be lifted while the remaining gangue is disposed on seafloor in appropriate ways. To apply column flotation, one of conventional methods in mineral processing, to seafloor mineral processing, the authors carried out simulating experiments of column flotation on deep seafloor using ores including copper, iron, lead and zinc as metallic elements. Prior to the experiments at high pressures, preparatory experiments at the atmospheric pressure were carried out to find out the optimum condition of the properties of pulp, a mixture of feed ore, water and chemical reagents. In flotation experiments at high pressures, formation and overflow of froth layer by bubbling were observed at 1MPa in both of pulps with pure water and artificial seawater. The analytical data showed that the concentration of metallic elements such as copper and zinc in the concentrates recovered from the experiments was higher than that in the feed ores while the concentration of silicon and calcium, which are assigned to gangue, in the concentrates was lower than that in the feed ores. These results suggest that column flotation can be applied to operation on seafloor.

scholarly journals Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

2017 ◽  
Author(s):  
Christoph Steinhausen ◽  
Grazia Lamanna ◽  
Bernhard Weigand ◽  
Rolf Stierle ◽  
Joachim Groß ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Raman Scattering ◽  
High Pressures ◽  
Region Of Interest ◽  
Theoretical Models ◽  
Nitrogen Atmosphere ◽  
Material Surface ◽  
Atmospheric Conditions ◽  
Mixing Processes ◽  
Two Phase

The disintegration process of liquid fuel within combustion chambers is one of the most important parameters forefficient and stable combustion. Especially for high pressures exceeding the critical value of the injected fluids the mixing processes are not fully understood yet. Recently, different theoretical macroscopic models have been introduced to understand breakdown of the classical two phase regime and predict the transition from evaporation to a diffuse-mixing process. In order to gain deeper insight into the physical processes of this transition, a parametric study of free-falling n-pentane droplets in an inert nitrogen atmosphere is presented. Atmospheric conditions varied systematically from sub- to supercritical values with respect to the fluid properties. An overlay of a diffuse lighted image with a shadowgram directly in the optical setup (front lighted shadowgraphy) was applied to simultaneously detect the presence of a material surface of the droplet as well as changes in density gradients in the surrounding atmosphere. The experimental investigation illustrates, that the presence of a material surface cannot be shown by a direct shadowgram. However, reflections and refractions caused by diffuse ambient illumination are able to indicate the presence of a material surface. In case of the supercritical droplet injections in this study, front lighted shadowgraphy clearly revealed the presence of a material surface, even when the pre-heated droplets are released into a supercritical atmosphere. This detection of the droplet interface indicates, that the droplet remains subcritical in the region of interest, even though it is injected into a supercritical atmosphere. Based on the adiabatic mixing assumption recent Raman-scattering results in the wake of the droplet are re-evaluated to compute the temperature distribution. Presented experimental findings as well as the re-evaluation of recent Raman scattering results are compared to thermodynamic models to predict the onset of diffuse-mixing and supercritical disintegration of the droplet. Additionally, a one dimensional evaporation model is used to evaluate the validity of the adiabatic mixing assumption in the estimation of the droplet temperature. The presented findings contribute to the understanding of recent theoretical models for prediction of spray and droplet disintegration and the onset of diffuse-mixing processes.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4635

scholarly journals Heat transfer and entropy generation in a microchannel with longitudinal vortex generators using Nanofluids

2020 ◽  
Author(s):  
Amin Ebrahimi ◽  
Farhad Rikhtegar Nezami ◽  
Amin Sabaghan ◽  
Ehsan Roohi
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Single Phase ◽  
Pure Water ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Working Fluid ◽  
Two Phase ◽  
Rectangular Microchannel ◽  
Important Conclusion

Conjugated heat transfer and hydraulic performance for nanofluid flow in a rectangular microchannel heat sink with LVGs (longitudinal vortex generators) are numerically investigated using at different ranges of Reynolds numbers. Three-dimensional simulations are performed on a microchannel heated by a constant heat flux with a hydraulic diameter of 160 μm and six pairs of LVGs using a single-phase model. Coolants are selected to be nanofluids containing low volume-fractions (0.5%–3.0%) of Al2O3 or CuO nanoparticles with different particle sizes dispersed in pure water. The employed model is validated and compared by published experimental, and single-phase and two-phase numerical data for various geometries and nanoparticle sizes. The results demonstrate that heat transfer is enhanced by 2.29–30.63% and 9.44%–53.06% for water-Al2O3 and water-CuO nanofluids, respectively, in expense of increasing the pressure drop with respect to pure-water by 3.49%–16.85% and 6.5%–17.70%, respectively. We have also observed that the overall efficiency is improved by 2.55%–29.05% and 9.78%–50.64% for water-Al2O3 and water-CuO nanofluids, respectively. The results are also analyzed in terms of entropy generation, leading to the important conclusion that using nanofluids as the working fluid could reduce the irreversibility level in the rectangular microchannel heat sinks with LVGs. No exterma (minimums) is found for total entropy generation for the ranges of parameters studied.

Temperature Dependent Solubility of Benzoic Acid in Aqueous Phase and Aqueous Mixtures of Aliphatic Alcohols

2020 ◽  
Vol 234 (11-12) ◽  
pp. 1771-1787
Author(s):  
Sayyar Muhammad ◽  
Sofia Sanam ◽  
Hamayun Khan ◽  
Akhtar Muhammad ◽  
Sabiha Sultana
Keyword(s):  
Benzoic Acid ◽  
Aqueous Phase ◽  
Linear Trend ◽  
Pure Water ◽  
Binary Solvents ◽  
Aqueous Mixtures ◽  
Analytical Technique ◽  
Temperature Range ◽  
Acid Solubility ◽  
Ethanol In Water

AbstractThe benzoic acid solubility in aqueous phase and in various aqueous mixtures of methanol, ethanol and 2-propanol was determined at temperatures ranging from 303 to 333 K by an analytical technique. The results showed that the solubility of the acid in alcohols-water binary mixtures is high as compared to pure aqueous phase. The addition of alcohols to water favors the dissolution of benzoic acid which increases further with the increase in alcohols content of water within the investigated temperature range. The benzoic acid solubility in water alone and aqueous mixtures of the selected alcohols was in the order of; 2-propanol in water > ethanol in water > methanol in water > pure water. It is also observed that within the investigated temperature range, the acid solubility increases with rise in temperature in both the aqueous phase and alcohols-water binary solvents. The logarithm of the mole fraction of the acid’s solubility also showed a linear trend against the temperature. The experimental results obtained in the current study were compared with the reported literature for the studied acid and other organic acids in various solvents and showing a good agreement. The study will have implications in the processes involving separation, crystallization and pharmaceutical formulation in various industries.

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