Dielectric Constant Of Mixture Research Articles

Operational control of the parameters of liquid fuels and lubricants with impurities

The possibilities of operational control of the parameters of liquid fuels and lubricants with impurities using the resonator method of microwave dielectrometry are considered. Preliminary studies of liquid fuels and lubricants (gasolines, diesel fuels, kerosene, oils) showed that the values ​​of the real and imaginary components of the complex dielectric constant of the listed fuels and lubricants are in the operating range of the resonator microwave dielectrometer.
 The high resolution of the microwave resonator method determines the prospects of using this method for analyzing the complex dielectric constant of mixtures of fuels and lubricants with various impurities, including water, alcohols, benzene, etc.
 For a mixture of gasoline with benzene, it was experimentally established that with a small addition of benzene (no more than 15%), an increase in the real component of the complex dielectric constant of the mixture is observed, and with a benzene content exceeding 15%, an increase in both components of the complex dielectric constant of the mixture takes place.
 The process has also been installed, but the NHF dielectrometer has made it possible to identify the transformer in real time due to the presence of water in the amount of 14, 28 and 56 grams per ton of oil. The research results indicate that the microwave dielectrometry method can be considered promising for monitoring the quality of transformer oil both during the filling process and for monitoring its quality during the operation of high-voltage transformers.
 The results of the initial stage of research on alcohol gasolines have not yet revealed the predominant effect of the alcohol additive on the location of the experimental points on the complex plane. This circumstance is most likely due to the fact that alcohol gasolines with a close octane number can have a significantly different chemical composition.

Like dissolves like: A first-principles theory for predicting liquid miscibility and mixture dielectric constant.

Liquid mixtures are ubiquitous. Miscibility and dielectric constant are fundamental properties that govern the applications of liquid mixtures. However, despite their importance, miscibility is usually predicted qualitatively based on the vaguely defined polarity of the liquids, and the dielectric constant of the mixture is modeled by introducing mixing rules. Here, we develop a first-principles theory for polar liquid mixtures using a statistical field approach, without resorting to mixing rules. With this theory, we obtain simple expressions for the mixture's dielectric constant and free energy of mixing. The dielectric constant predicted by this theory agrees well with measured data for simple binary mixtures. On the basis of the derived free energy of mixing, we can construct a miscibility map in the parameter space of the dielectric constant and molar volume for each liquid. The predicted miscibility shows remarkable agreement with known data, thus providing a quantitative basis for the empirical "like-dissolves-like" rule.

Dielectric Constant of Mixtures of Carbon Dioxide and n-Dodecane Between 283 K and 343 K

The dielectric constant (relative permittivity) of mixtures of carbon dioxide (CO2) and n-dodecane (n-C12H26) was experimentally determined for temperatures between 283 K and 343 K in a purpose-built apparatus which enabled simultaneous measurements of relative permittivity and liquid-phase mass density. A flat response of the dielectric constant with respect to frequency was observed between 1 kHz and 400 kHz. The mixture dielectric constant was found to be inversely proportional to the temperature and to the CO2 concentration in the liquid mixture. The departure from the relative permittivity ideal mixture behavior (calculated using the classical Bottcher mixing rule) was correlated via a first-order Redlich-Kister volume fraction expansion with a temperature dependent parameter. The RMS deviation of this method was 0.37 %. The liquid-phase mass density was predicted by the PCP-SAFT equation of state with a RMS deviation of 0.26 %.

The role of dielectric constant in sodium chloride solution chemistry: Magnitude of super saturation

The effect of ethanol addition to aqueous semi saturated NaCl solutions on the super saturation was studied. The amount of precipitated salt was found to increase as the percent of added ethanol increased. The rates of formation of precipitate were calculated and found to increase with decrease of the weighted average of the solvents mixture dielectric constant, e, but levels out at e ≈ 50. The solubility of salt was then connected with the dielectric constant and a zero solubility was observed at e = 35. A magnitude of super saturation was defined for the measurement of solubility. Key words: Dielectric constant, precipitate, activation energy, magnitude of super saturation.

A Local-Composition Model for the Prediction of Mixture Dielectric Constants

A local composition model is developed for mixture dielectric constants based on the nonrandom two-liquid (NRTL) model commonly used for correlating activity coefficients in vapor−liquid equilibrium (VLE) data regression. In this model the NRTL local compositions, which represent an effective local molecular structure, are the counterpart of the Kirkwood factor g, which in dielectric constant theory characterizes local molecular orientations and their effect on the static dielectric constant. The resultant model requires values for the pure-component dielectric constant and binary NRTL model parameters available from VLE data compilations or predicted from the universal functional activity coefficient model (UNIFAC). It is predictive in that no mixture dielectric constant data are used and there are no adjustable parameters. Predictions made on 16 binary and six ternary systems at various compositions and temperatures compare favorably with extant correlations that require experimental values to fit an adjustable parameter in the mixing rule and are significantly improved over values predicted by Oster's equation that also has no adjustable parameters.

The determination of dielectric constants of mixtures used in the treatment of epilepsy and the encapsulation of phenytoin in a titania matrix

In this study it is shown that an anticonvulsant drug such as phenytoin can successfully be encapsulated in a titania matrix. Infrared studies show that as a result of the encapsulation process, the structure of phenytoin is not chemically altered. BET studies show that the surface area of phenytoin is small in comparison to the surface area obtained following adsorption of the drug onto the surface of the titania. The dielectric constants of phenytoin, valproic acid and mixtures of the two were calculated. They were found to be independent of composition. Using stereotactic surgery the phenytoin/titania reservoir was implanted in the temporal lobe of the brain of a Winstar rat. Furthermore, the implanted device was found to be biocompatible with the surrounding tissue. An immunohistochemical study showed that chemical changes did not occur in the neurons surrounding the implant. Simulation studies show how to identify the pore size distribution required for the successful encapsulation of phenytoin. The formation of electrical dipoles within the titania matrix is discussed.

Kinetic Study of Corrosion of Copper in Phosphoric Acid Tert-Butanol Electropolishing Mixtures

The rate of copper dissolution in presence of phosphoric acid tert-butanol electropolishing mixtures was studied by measuring the limiting current which represents the rate of electropolishing. The rate of dissolution decreases by increasing phosphoric acid concentration, electrode height and the mole fraction of alcohol. The data show that addition of tert-butanol to phosphoric acid decreases the rate of dissolution of copper by an amount ranging from 68 % to 90 % depending on the dielectric constant of mixtures. Thermodynamic parameters are given.

Capacitance probes for solids volume concentration and velocity measurements in industrial fluidized bed reactors

The capacitive measurement of solids volume concentrations is based on the determination of the relative dielectric constant of a fluid–solids suspension in the capacitance sensor volume. The suitability of various theoretical and empirical calibration relationships that relate the volumetric fraction of the solids to the mixture dielectric constant has been investigated and a new empirical calibration relationship is suggested. The application of the calibration relationship to capacitive measurements in high-temperature fluidized bed reactors is demonstrated. Measurements of solids volume concentrations and velocities in the upper dilute zone of a cold model circulating fluidized bed (CFB) and in the bottom zone of a large-scale industrial CFB boiler illustrate the value of capacitance probes for local flow structure investigations.

Calculation of the Static Dielectric Constant of Multipolar Mixtures by Perturbation Theory. An Application to Supercritical Water‐Benzene Mixtures

AbstractSecond‐order perturbation theory for the molecular pair correlation function, together with a y‐expansion of the static dielectric constant (ϵ) is used to predict and interpret ϵ for supercritical benzene‐water mixtures. Our predictions are compared directly with experimental results. We find that this approach, which was previously found successful provided y<3 for neat multipolar fluids, is also successful here in predicting the excess mixture dielectric constant, λϵ. The results are quantitative to semi‐quantitative in accuracy depending slightly on the model chosen and the composition of the mixture. No adjustable parameters were used. We interpret our results in terms of underlying molecular clusters, and make a comparison with the predictions of another (non‐molecular) theory.

Studies of mixing formulae in the complex plane

Remote sensing signal monitoring is considered. Mixing rules that have been introduced to explain the permittivity of mixtures by analytically continuing these to the whole complex plane are discussed. Equipermittivity curves for both the real and imaginary parts of the mixture dielectric constant (the imaginary part of the permittivity is a measure for the dielectric losses) are studied. These form a map on the complex plant, illustrating the nature of a mixing rule better than the classical way of presenting the mixture permittivity as a function of the volume fraction of a component in the mixture. These maps naturally vary for a given mixing rule as the volume fraction is changed, but, in principle, the structure is the same. The resulting illustrations show that certain mixing formulae can be conceived as a continuum that gradually changes from the Maxwell-Garnett formula through Polder-van Santen and coherent potential formulas to the so-called exponential formulas.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dielectric behavior of the binary mixtures of n-hexane with toluene, chlorobenzene and 1-hexanol

Mixture dielectric constants e , were measured for the binaries of n -hexane wlth toluene, chlorobenzene, and l-hexanol at 90, 40, 50, and 60 OC. Also the values of e , were cakuiated by using the Frohlich equation as well as an equation based on slgnllcant liquid structure (SLS) theory wlng pure-component properties only lor the binaries studied. A comparison of the calculated and experimental data showed that the SLS equation gave better results than the Frohlich equation.

Measurement of Radio Wave Velocities in the Firn Zones of Polar Ice Sheets (Abstract only)

A common-reflection point profiling experiment to obtain electromagnetic wave velocities in the ice at Dome C at 35 MHz was carried out to a maximum antenna separation of 2 km. Four different recording systems were used for this experiment. The echoes from numerous internal reflecting horizons within the ice and the bedrock were recorded in four different ways: in A-display form on film using an oscilloscope, in intensity-modulated form using the Honeywell Visi-corder and thermal intensifier on heat-sensitive silver paper, and in both raw and signal-averaged form on magnetic tape.Travel times of oblique reflections from nearly 160 internal layers down to a depth of 2 600 m and reflections from the ice bottom were measured at each station along the profile. The average wave velocities from the surface of each internal layer were measured to obtain a continuous mean velocity vs depth profile.Velocity-density models derived from the dielectric mixture equations of Looyenga, Böttcher, Lichtenrecker, Hanai-Bruggeman and Wiener were compared against the measurements. In addition Robin's empirical relationship was also used in this study. The preliminary results show that the observed velocity depth profile for the ice column is compatible with Wiener's equation (with Formzahl = 0) and a newly derived empirical relationship (from this study) ofwhere γiis ice density, γffirn density, ε dielectric constant of mixture, and εidielectric constant of ice; γf&amp;gt;0.55 kg m−3. It appears that the electromagnetic wave velocity in the firn is 20 m MS−1or more, which is higher than previously assumed.The above models were also compared with velocity measurements in the Devon Island bore holes (Robin 1975) and at several sites on the Ross Ice Shelf where the ice is relatively thin compared to Dome C so that the effect of firn on mean velocities is more pronounced. The results for these sites suggest again that Wiener's equation and empirical relationship from this study produce velocities compatible with the observed values.

Measurement of Radio Wave Velocities in the Firn Zones of Polar Ice Sheets (Abstract only)

A common-reflection point profiling experiment to obtain electromagnetic wave velocities in the ice at Dome C at 35 MHz was carried out to a maximum antenna separation of 2 km. Four different recording systems were used for this experiment. The echoes from numerous internal reflecting horizons within the ice and the bedrock were recorded in four different ways: in A-display form on film using an oscilloscope, in intensity-modulated form using the Honeywell Visi-corder and thermal intensifier on heat-sensitive silver paper, and in both raw and signal-averaged form on magnetic tape.Travel times of oblique reflections from nearly 160 internal layers down to a depth of 2 600 m and reflections from the ice bottom were measured at each station along the profile. The average wave velocities from the surface of each internal layer were measured to obtain a continuous mean velocity vs depth profile.Velocity-density models derived from the dielectric mixture equations of Looyenga, Böttcher, Lichtenrecker, Hanai-Bruggeman and Wiener were compared against the measurements. In addition Robin's empirical relationship was also used in this study. The preliminary results show that the observed velocity depth profile for the ice column is compatible with Wiener's equation (with Formzahl = 0) and a newly derived empirical relationship (from this study) of where γi is ice density, γf firn density, ε dielectric constant of mixture, and εi dielectric constant of ice; γf&gt;0.55 kg m−3. It appears that the electromagnetic wave velocity in the firn is 20 m MS−1 or more, which is higher than previously assumed.The above models were also compared with velocity measurements in the Devon Island bore holes (Robin 1975) and at several sites on the Ross Ice Shelf where the ice is relatively thin compared to Dome C so that the effect of firn on mean velocities is more pronounced. The results for these sites suggest again that Wiener's equation and empirical relationship from this study produce velocities compatible with the observed values.

An Empirical Model for the Complex Dielectric Permittivity of Soils as a Function of Water Content

The recent measurements on the dielectric properties of soils have shown that the variation of dielectric constant with moisture content depends on soil types. The observed dielectric constant increases only slowly with moisture content up to a transition point. Beyond the transition it increases rapidly with moisture content. The moisture value at transition region was found to be higher for high clay content soils than for sandy soils. Many mixing formulas reported in the literature were compared with, and were found incompatible with, the measured dielectric variations of soil-water mixtures. A simple empirical model was proposed to describe the dielectric behavior of the soil-water mixtures. This model employs the mixing of either the dielectric constants or the refraction indices of ice, water, rock, and air, and treats the transition moisture value as an adjustable parameter. The calculated mixture dielectric constants from the model were found to be in reasonable agreement with the measured results over the entire moisture range of 0-0.5 cm3/cm3. The transition moistures derived from the model range from 0.16 to 0.33 and are strongly correlated with the wilting points of the soils estimated from their textures. This relationship between transition moisture and wilting point provides a means of estimating soil dielectric properties on the basis of texture information.

DIELECTRIC CONSTANT LOGGING A PROGRESS REPORT

The recent evolution of equipment capable of measuring the relative dielectric constant of a formation has stimulated new approaches to the evaluation of water saturation. In many oil productive reservoirs, the formation water resistivities are either unknown or are very high; thus complicating conventional resistivity dependent solutions for water saturation.By determining the relative dielectric constant of the formation and through application of the Lichtnecker and Rother equation for the dielectric constant of mixtures, the analyst may identify the presence of hydrocarbons and in many cases, quantify reserves. Additionally, a quick look overlay technique for qualitative evaluation can be utilized. These procedures can be of great help in both exploration and development environments where conventional methods have led to confusion.

Measurement of complex dielectric constant of inhomogeneous materials in the range 102?107 Hz

A method of measuring the complex dielectric constant of a mixture composed of a disperse substance and water by insertion of dielectric spacers between the electrodes and the investigated substance is discussed. This system exhibits relaxation of the Maxwell-Wagner type in the conductivity range 10−8–10−2 Ω−1·m−1. By constructing and analyzing Cole-Cole diagrams it is possible to determine the complex dielectric constant of mixtures with a water content of 1–100 wt.% in the frequency range 102–107 Hz.

Compressed-liquid dielectric constants and derived excess volumes for simple liquid mixtures: N 2 + CH 4 and Ar + CH 4

Liquid mixture excess volumes have been determined at 100 to 115 K with pressures up to 20 MPa for nitrogen + methane and argon + methane at five compositions each. The method involved measurement of pure-component and mixture dielectric constants which were combined with previously published pure-component molar volumes. Excess volumes were derived on the assumption of zero excess in the Clausius-Mossotti function. Discrepancies between the present V E results and previously reported values based on volumetric measurements are probably within the uncertainties of the previous studies. Excess isothermal compressibilities can be readily derived from the results. Values of this excess property were shown to be a major contribution to the isothermal compressibility of nitrogen + methane at lower pressures.

The dielectric constants of mixtures and of the supercritical region of some hydrogen-bonded fluids

The dielectric constants of mixtures and of the supercritical region of some hydrogen-bonded fluids

Dielectric constants of mixtures of tri-n-butyl phosphate and water and tri-n-butyl phosphate and mineral acids

Dielectric constants of mixtures of tri-n-butyl phosphate and water and tri-n-butyl phosphate and mineral acids

Dielectric Investigation on Coals. III. On a Variety of Coals

Abstract By using a method of paraffin-wax mixture dielectric constants were determined for a variety of coals including five specimens from foreign sources. It was found that dielectric constants of lower rank coals are generally higher than those of bituminous coals of higher rank. Large difference in dielectric behavior was detected among the coal specimens (C % 87–90) from different sources. The present dielectric measurement supported the view that the nature of Japanese coals is particular as compared with European and American coals.