Density Of Liquid Phase Research Articles

Volumetric Properties of Binary and Ternary Solutions in the Water–Urea–Ammonium Sulfamate System

Densities of liquid phases in the water–urea–ammonium sulfamate ternary system and in the binary water–ammonium sulfamate subsystem were investigated in a wide concentration range at 288.15, 298.15 and 323.15 K. A volumetric model of the aqueous ternary solutions was proposed.

The Causes of Formation of the Triple Junctions of Grain Boundaries Containing Excess Free Volume in fcc Metals at Crystallization

The formation conditions of strained (non-equilibrium) triple junctions of grain boundaries were studied by the method of molecular dynamics. It is shown that strained triple junctions, containing excess free volume, mainly forms during crystallization process in the result of "locking" of the liquid phase density at a meeting of the three crystallization fronts and, as a consequence, of the concentration of excess free volume in the triple junction after solidification.

Thermodynamic Properties of Selected Homologous Series of Ionic Liquids Calculated Using Molecular Dynamics.

This work presents a molecular dynamics simulation study concerning the thermodynamic data of ionic liquids (ILs) including phase change enthalpies, liquid phase densities, radial and spatial distribution functions, and diffusive properties. Three homologous series of ILs were selected for this study, namely, 1-alkyl-3-methylimidazolium tetrafluoroborates, hexafluorophosphates, and 1,1,2,2-tetrafluoroethanesulfonates, so that properties of 36 ILs are calculated in total. The trends of calculated properties are compared to available experimental data and thoroughly discussed in context of the homologous series. The calculated trends of the vaporization enthalpies within the series are supported by analyzing the structural properties of the ILs. An excellent agreement of calculated structural properties (liquid phase density) with the experimental counterparts is reached. The calculated enthalpic properties are overestimated considerably; thus, further development of the force fields for ILs is required.

ВЛИЯНИЕ ЛЕГИРУЮЩИХ КОМПОНЕНТОВ НА ФОТОКАТАЛИТИЧЕСКУЮ АКТИВНОСТЬ ДИОКСИДА ТИТАНА АНАТАЗНОЙ МОДИФИКАЦИИ

nitrogen atoms was carried out by introducing ammonia into freshly titanium oxyhydrate suspension followed by heat treatment in a tubular furnace. Doping of aluminum atoms of titanium dioxide was conducted by introducing the titanium tetrachloride with aluminum chloride followed by hydrolysis and thermal treatment of the resulting product. Soot doped anatase titanium dioxide with particle size of 40-80 nm was introduced into the analyzed dye solution, which is then subjected to UV irradiation for 5 hours periodically sediment detachment. The radiation source used ultraviolet lamp UV-B brand TSR-125 (with a working area of wavelengths of 250-400 nm). An analysis of the optical density of the test liquid phase, carried out using phot oelectric colorimeter KFK-2. As a result of experiments to study the effect of alloying elements on the catalytic properties of TiO

Modeling of Pressure Dependence of Interfacial Tension Behaviors of a Complex Supercritical CO2 + Live Crude Oil System Using a Basic Parachor Expression

Parachor based basic expressions are often used to model the experimentally observed pressure dependence of interfacial tension (IFT) behaviors of complex supercritical CO2 + crude oil (dead or live) mixtures at elevated temperatures. However, such modeling requires compositions and densities of the equilibrium liquid and vapor phases and molecular weights of various components present in the system. In the absence of measured data, often phase behavior packages are used for obtaining these input data for performing calculations. Very few researchers have used experimentally measured input data for performing parachor based modeling of the experimental IFT behaviors of complex supercritical CO2 + live crude oil systems. This study presents the results of a basic parachor model based modeling of pressure dependence of IFT behaviors of a complex supercritical CO2 + live crude oil system for which experimentally measured input data is available in public domain. Though the calculated IFT behaviors showed significant deviation from the experimentally measured behaviors at a given pressure, calculated IFT versus pressure trends appeared to follow the experimental observed trends closely. Also, despite a large variation in the compositions of feed supercritical CO2 + live crude oil mixtures, both trends (calculated and experimental) converged rapidly to attain a near zero IFT condition at more or less same pressure.

Developing a new model for the determination of petroleum fraction PC-SAFT parameters to model reservoir fluids

In this work, PC-SAFT, an equation of state based on perturbation theory, is applied to predict the reservoir fluids phase behavior. PC-SAFT parameters for pure components have previously been assessed, but they cannot be determined for petroleum fractions with unspecified components and composition. In order to remove this difficulty and making use of PC-SAFT model in the reservoir fluids simulations, a new approach is studied which leads to appearing generalized correlations for the estimation of PC-SAFT parameters for petroleum cuts and plus fractions using only their molecular weight and specific gravity, without the essential need for the characterization of petroleum fractions in different homologous hydrocarbon families. The proposed technique is then validated with the reliable experimental PVT data of reservoir fluids, including saturation pressure and differential liberation test (oil formation volume factor, soluble gas oil ratio, and liquid phase density) for 10 oil samples. Subsequently, available experimental data are compared to results calculated by PC-SAFT model for all existing samples. Afterwards, a comparison between PC-SAFT model and two widely used cubic equations of state (PR and SRK EOS) was also conducted. The results demonstrated PC-SAFT model estimation capabilities and ease of use as an effective tool for describing the phase behavior of reservoir fluids in a wide range of scales and applications. Moreover, the effect of parameter tuning process on reduction of error values was investigated and acceptable results were obtained.

Communication: Dynamical density functional theory for dense suspensions of colloidal hard spheres.

We study structural relaxation of colloidal hard spheres undergoing Brownian motion using dynamical density functional theory. Contrary to the partial linearization route [D. Stopper et al., Phys. Rev. E 92, 022151 (2015)] which amounts to using different free energy functionals for the self and distinct part of the van Hove function G(r, t), we put forward a unified description employing a single functional for both components. To this end, interactions within the self part are removed via the zero-dimensional limit of the functional with a quenched self component. In addition, we make use of a theoretical result for the long-time mobility in hard-sphere suspensions, which we adapt to the inhomogeneous fluid. Our results for G(r, t) are in excellent agreement with numerical simulations even in the dense liquid phase. In particular, our theory accurately yields the crossover from free diffusion at short times to the slower long-time diffusion in a crowded environment.

Numerical investigation of combined chemical and electrochemical processes in Fe2O3 suspension electrolysis

Suspension electrolysis is a combined process of chemical and electrochemical reactions. The developed model for a parallel-plate electrochemical reactor is based on mixture model for suspension flow and balance equation for diluted species taking into account the dispersed phase content and ions migration due to the electrolyte current and partial dissolution of suspended particles in the suspension electrolysis. Electrochemical reactions are specified through flux boundary conditions at the electrode/electrolyte interface. The influence of the combined processes is reflected through the distribution of ions concentration profile in liquid phase and current density profile at the electrode surface. Numerical investigation indicates that about 90 % of the iron deposition flux is accommodated by an additional component flux due to the chemical reaction of partial dissolution of α-Fe2O3 particles in suspension electrolysis.

Estimation of Void Fraction for Homogenous Regime of Two-Phase Flows in Unstable Operational Conditions Using Gamma-Ray and Neural Networks

Almost all the multi-phase flow meters (MPFMs) using gamma-ray attenuation, are calibrated for liquid and gas phases with constant density and pressure. When operational conditions such as temperature and pressure change in pipelines, the radiation-based multi-phase flow meters would measure the flow rate with error. Therefore, performance of MPFMs would be improved by eliminating any dependency on the fluid properties such as density. In this work, a method based on dual modality densitometry combined with Artificial Neural Network (ANN) is proposed in order to estimate the void fraction in homogenous regime of gas-liquid two-phase flows in unstable operational conditions (changeable temperature and pressure) in oil industry. An experimental setup was implemented to generate the optimum required input data for training the network. ANNs were trained on the registered counts of the transmission and scattering detectors in various liquid phase densities and void fractions. Void fractions were predicted by ANNs with mean relative error of less than 0.78% in density variations range of 0.735 up to 0.98 g/cm3.

ReaxFF molecular dynamics simulations of intermediate species in dicyanamide anion and nitric acid hypergolic combustion

Ionic liquids based on the dicyanamide anion (DCA) are of interest as replacements for current hypergolic fuels, which are highly toxic. To better understand the reaction dynamics of these ionic liquid fuels, this study reports the results of molecular dynamics simulations performed for two predicted intermediate compounds in DCA-based ionic liquids/nitric acid (HNO3) combustion, i.e. protonated DCA (DCAH) and nitro-dicyanamide-carbonyl (NDC). Calculations were performed using a ReaxFF reactive force field. Single component simulations show that neat NDC undergo exothermic decomposition and ignition. Simulations with HNO3 were performed at both a low (0.25 g ml−1) and high (1.00 g ml−1) densities, to investigate the reaction in a dense vapor and liquid phase, respectively. Both DCAH and NDC react hypergolically with HNO3, and increased density led to shorter times for the onset of thermal runaway. Contrary to a proposed mechanism for DCA combustion, neither DCAH nor NDC are converted to 1,5-Dinitrobiuret (DNB) before thermal runaway. Details of reaction pathways for these processes are discussed.

A radiation-based hydrocarbon two-phase flow meter for estimating of phase fraction independent of liquid phase density in stratified regime

The fluid properties strongly affect the performance of radiation-based multiphase flow meter. By changing the fluid properties (especially density), recalibration is necessary. In this study, a method was presented to eliminate the dependency of multiphase flow meter on liquid phase density in stratified two phase horizontal flows. At the first step the position of the scattering detector was optimized in order to achieve highest sensitivity. Several experiments in optimized position were done. Counts under the full energy peak of transmission detector and total counts of scattering detector were applied to the Radial Basis Function neural network and the void fraction percentage was considered as the neural network output. Using this method, the void fraction was predicted independent of the liquid phase density change in stratified regime of gas–liquid two-phase flows with mean relative error percentage less than 1.2%.

Melting temperatures and possible precursor plastic phases of CCl4 and GeI4 as a function of pressure

The motivation for the present study is to be found in the recent experiments of Fuchizaki and Hamaya on GeI4. They observed a rapid increase in the melting temperature in going from atmospheric pressure to GPa. was found to be largely independent of pressure above this value. In this paper, heuristic arguments are presented to support the idea that until some critical pressure, a crystalline phase of SnI4, CCl4 and GeI4 molecular solids melts into a low density liquid. However, at this critical pressure, a phase boundary intersects , separating a low density liquid phase from a high density liquid. The new phase boundary is between the crystal and an amorphous molecular solid with increasing polymerisation as the pressure is increased.

Surrogate Generation and Evaluation for Diesel Fuel

The correct representation of a fuel in terms of its physical and chemical properties and its combustion kinetics poses a challenge to modern engine development when state-of-the-art simulation technology is used. In this context, a promising approach is the use of surrogates that emulate the properties of real fuels, where the surrogates are made up of a significantly lower number of components than the original fuels. The goal of this paper is to present an algorithm that can be used to generate surrogates composed of real chemical components, as opposed to pseudo-components. The algorithm was developed by simultaneously fitting the true boiling point (TBP) curve, the liquid density at 15 °C, and the cetane number. To illustrate the algorithm, surrogates for four different fuels were generated: a commercially available European diesel and three research diesel proposed by the Fuels for Advanced Combustion Engines (FACE) CRC Research Group. Two of the resulting surrogates were produced on a lab scale and subjected to laboratory examination. For validation, the experimental data for these two surrogates were compared to those for the target fuels and to data generated by thermodynamic models on the basis of the compositions of the surrogates. Both the fitted properties and additional properties, which were not used for fitting, were compared to experimental properties, such as the ASTM D86 boiling curve, content of aromatics, flash point, heating value, cloud point, viscosity, and temperature dependency of the liquid-phase viscosity and density. We demonstrate that the proposed algorithm generates surrogates of approximately 10 real components, which show excellent agreement with the original target fuels.

Optimization of crystal nucleation close to a metastable fluid-fluid phase transition.

The presence of a metastable fluid-fluid critical point is thought to dramatically influence the crystallization pathway, increasing the nucleation rate by many orders of magnitude over the predictions of classical nucleation theory. We use molecular dynamics simulations to study the kinetics of crystallization in the vicinity of this metastable critical point and throughout the metastable fluid-fluid phase diagram. To quantitatively understand how the fluid-fluid phase separation affects the crystal nucleation, we evaluate accurately the kinetics and reconstruct the thermodynamic free-energy landscape of crystal formation. Contrary to expectations, we find no special advantage of the proximity of the metastable critical point on the crystallization rates. However, we find that the ultrafast formation of a dense liquid phase causes the crystallization to accelerate both near the metastable critical point and almost everywhere below the fluid-fluid spinodal line. These results unveil three different scenarios for crystallization that could guide the optimization of the process in experiments

Prediction of Sanchez‐Lacombe equation of state characteristic parameters for plus fractions

Sanchez‐Lacombe is one of the main polymeric equations of state that is used to predict thermodynamic properties of polymer solutions. Due to the similarity of the physical behaviour of polymer solutions and black oil, Sanchez‐Lacombe is also recommended to predict the liquid density of hydrocarbon fluids. In conventional thermodynamic equations of state, each component of the fluid is specified with some characteristic parameters such as the acentric factor, critical temperature, and critical pressure. Similarly, in the Sanchez‐Lacombe equation of state each component has some characteristic parameters which are obtained for pure components. Since there are no correlations for plus fractions (unknown fractions), the aim of this study is to present empirical correlations to predict the characteristic parameters of plus fractions based on experimental data. These empirical correlations are then used so that the Sanchez‐Lacombe equation of state can be applied to determine the liquid phase density of hydrocarbon fluids.

Measuring and Modeling the Solubility and Density for CO2–Toluene and C2H6–Toluene Systems

An accurate thermodynamic model of CO2/toluene and C2H6/toluene systems is required to improve the design of industrial processes including separation, supercritical extraction, and fine particle production. We present new sets of experimental solubility data for CO2 (298.15 ≤ T ≤363.15 K and P ≤ 5.1 MPa) and C2H6 (294.15 ≤ T ≤363.15 K and P ≤ 3.65 MPa) in toluene as well as the corresponding liquid phase densities. The Peng–Robinson equation of state/excess Gibbs free energy model (PR-EoS/GE) is applied to represent the experimental data over a wide range of temperatures and pressures. Our results show acceptable agreement between the experimental and calculated solubility and density data. The presented experimental data and thermodynamic model will find applications in the design of separation, extraction, and fine particle production processes.

Vaporization characteristics of suspended droplets of biodiesel fuels of Indian origin and their diesel blends – An experimental study

For a liquid fuel, its vaporization characteristics are important. The determination of vaporization rates for alternative fuels such as biodiesel and its diesel blends is reported in this work. For this purpose, suspended droplet technique in conjunction with optical measurement of the droplet diameter is used. The physical processes occurring during the vaporization are studied at temperatures lower than the boiling point of the respective fuels to ascertain all the regimes of vaporization. Further, the vaporization characteristics are related to the composition of the fuel, which governs its thermal and physical properties. This study becomes important due to absence of such a comprehensive data in literature, and attempts to create a useful data-base for vaporization rates and related features of biodiesel fuels produced from sources such as jatropha, karanja, palm and coconut, and their diesel blends. The overall evaporation rates of neat and fuel blends are reported systematically. For neat fuels, the vaporization rates are seen to correlate directly with two parameters namely, heat transport and mass transport parameters, constituted using the gas-phase thermal and physical properties, as well as the liquid-phase density. Also, the vaporization rate is seen to inversely vary with a parameter called long chain saturation factor. All these parameters depend on the composition of the fuel.

Numerical investigation of quasi-static bubble growth and detachment from submerged orifices in isothermal liquid pools: The effect of varying fluid properties and gravity levels

The present investigation, identifies the exact quantitative effects of fundamental parameters, on the detachment characteristics of isolated bubbles, emanating quasi-statically from submerged orifices into isothermal liquid pools. For this purpose, a Volume of Fluid (VOF) based interface capturing approach is further improved, for the conduction of axisymmetric and 3D numerical experiments on adiabatic bubble growth dynamics. The predictions of the model, are quantitatively validated against literature available experimental data, showing excellent agreement. Two series of numerical experiments are performed, quantitatively exploring the parametric effects of the liquid phase properties in five different gravity levels, and the effect of the gravity vector direction inclination angle, respectively. It is found that the bubble detachment characteristics, are more sensitive in the variation of the surface tension, liquid phase density and gravity, while the effect of liquid phase dynamic viscosity is generally minimal. From dimensionless analysis, two correlations are derived, which for the examined range of Eötvos numbers, are able to predict the equivalent bubble detachment diameter and the bubble detachment time, respectively. It is also found that the bubble detachment characteristics, reduce significantly as the gravity vector direction gradually deviates from being parallel to the bubble injection orifice, following a non-linear decrease.

Modified liquid entrainment fraction correlation for varying pipe orientation and system pressure

2015 Elsevier Ltd. All rights reserved. Review Cioncolini and Thome (2012) proposed a correlation to predict the liquid entrainment fraction in vertical upward gas–liquid annular two phase flow. Their correlation is based on a two-step method of predictor and corrector technique. This technique calculates an approximate value of liquid entrainment fraction in the first (predictor) step and then recalculates its corrected value in the second (corrector) step. In the predictor step, as shown in Eq. (1), the predicted value of gas core Weber number (Wec,p) is calculated using gas density (qG) [kg/m], superficial gas velocity (USG) [m/s], pipe diameter (D) [m] and the gas–liquid interface surface tension (r) [N/m]. Based on this predicted Weber number, the first estimate of liquid entrainment fraction (Ep) is calculated from Eq. (2) where the multiplying factor (n) of 279.6 and exponents of 0.8395 and 2.209 are determined from the experimental data for vertical upward flow by solving for a nonlinear regression problem and are based on least absolute residuals. Next, the gas core density (qc) [kg/m] based on two phase flow quality (x) and the gas and liquid phase density (qG and qL) is calculated using Ep in Eq. (3) and the corrected values of gas core Weber number (Wec) and liquid entrainment fraction (E) are calculated in Eqs. (4) and (5), respectively. Wec;p 1⁄4 DqGU 2 SG r ð1Þ Ep 1⁄4 ð1þ n We 0:8395 c;p Þ 2:209 where n 1⁄4 279:6 ð2Þ qc 1⁄4 xþ Epð1 xÞ ðx=qGÞ þ Epð1 xÞ=qL ð3Þ Wec 1⁄4 DqcU 2 SG r ð4Þ E 1⁄4 ð1þ n We 0:8395 c Þ 2:209 where n 1⁄4 279:6 ð5Þ The correlation of Cioncolini and Thome (2012) is based on the experimental data set consisting of 2293 data points for circular pipes and 71 data points for non-circular pipes in vertical upward flow. Their correlation also used 96 data points in horizontal two phase flow for preliminary comparison and to validate their correlation (based on data in vertical upward two phase flow). For horizontal flow, Cioncolini and Thome (2012) found a significant scatter between the measured data and the predicted values however; they concluded that the general trend of the liquid entrainment in horizontal flow was correctly captured by their correlation.

Dissolution–precipitation processes in tank experiments for testing numerical models for reactive transport calculations: Experiments and modelling

In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective–diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time.