Phase Composition Data Research Articles

Analysis of the behavior of a gas-generating system under runaway conditions in a closed vessel

In the event of a runaway reaction, emergency relief systems (ERS) act as the last line of defense against the vessel explosion. To date, ERS design for scenarios involving the runaway of chemical mixtures that generate gaseous reaction products remains very challenging as it requires the prediction of the gas generation rate under runaway conditions at large scale. Current methodologies for the assessment of the gas generation rate are based on pseudo-adiabatic calorimetric experiments at laboratory scale in which the temperature and pressure profiles resulting from the runaway are used to assess the gas generation rate using the ideal gas law. The gas generation rate needs to be further corrected for the thermal inertia (φ-factor), of the calorimetric cell used (φ>1) to predict large scale behavior (φ≈1). The work described in this paper focuses on evaluating the capability of this approach to accurately assess the gas generation rate. It uses a dynamic simulator tool based on rigorous thermodynamics to calculate the temperature, pressure, and the composition of each component in a closed vessel containing a gas generating reactive mixture (decomposition of 20 % w/w di-tert butyl peroxide in toluene) under runaway conditions over a range of initial vessel fill levels. The results were analyzed to develop a better understanding of the phenomena that govern the thermal behavior of the mixture, the overall pressurization of the vessel, rate of generation of the gaseous products and its distribution in the liquid and vapor phase of the vessel as the runaway reaction occurs. The simulated pressure, temperature and phase composition data rigorously calculated by the simulator were used to assess and highlight the limitations of using the temperature and pressure in a closed vessel and the ideal gas law to evaluate the gas generation rate. The simulations were also used to evaluate the validity of φ-factor correction methods currently available in the literature.

Full-scale investigations of initial deposits formation in a cement plant co-fired with coal and SRF

This work investigates the initial (short-term) deposit formation in a cement calciner co-fired with coal and SRF (Solid Recovered Fuel). The main objective was to evaluate and compare the tendencies of deposit formation (i.e. material deposition rate and composition) at different locations (heights) in the calciner system, during different operation conditions. A steel probe was used to collect initial deposits from four different sampling locations: i) in the kiln riser (two sampling locations), ii) in the mid calciner, and, iii) at the outlet from the bottom stage preheater cyclone (C5). After an exposure time of the probe between 1 and 20 min, the collected deposit samples were weighted and characterized by SEM-EDX, ICP-OES/IC, and XRD. Plant operation data, measured gas temperatures, as well as gas phase composition data (i.e. KCl(g) and SO2(g)), supported the evaluation of deposit formation. Due to high particle flux (up to approx. 61,000 kg/(m2·h) in the riser duct), the average net deposit formation rate was around 500 kg/(m2·h) for 1 min exposure time, decreasing to <100 kg/(m2·h) for exposure times ≥4 min (due to spontaneous shedding and erosion). The deposits contained primarily five crystalline phases (CaO, CaCO3, Ca(OH)2, KCl, and SiO2), which is in general consistence with the composition of the admitted preheated raw meal (C4 meal) at measurement locations, with a slight enrichment in KCl, suggesting some condensation of volatile elements from the high-temperature gas phase on the surface of the somewhat colder deposit particles. Further, the deposit samples obtained in the kiln riser had a higher degree of calcination (higher proportion of CaO as compared to CaCO3) as compared to the admitted C4 meal, suggesting carry-over of dust from the kiln feed pipe, or fast calcination of the riser meal due to high temperature.The collected short-term deposits differ significantly from long-term (mature) deposits, which have previously been collected from the site, in terms of chemical and physical properties. Compared to short-term deposits, which had a content of KCl in the range of approx. 3–5 wt%, the content of KCl in the mature deposits increased substantially from around 2 wt% in samples from the kiln riser area to a level of >20 wt% in the calciner and C5 cyclone area, implying significant accumulation of KCl caused by volatile circulation and condensation from the hot gas on surfaces with locally lower temperatures. The most prevalent crystalline phases in the mature deposits were KCl, CaCO3, and the mineral spurrite (Ca5(SiO4)2CO3). The presence of spurrite implied that SiO2 reacts with CaCO3, or with CaO and gaseous CO2, to form spurrite during long-term deposit build-up and maturation.Overall, the results from this work suggest that the short-term deposit formation in the cement calciner is dominated by impaction. The composition of the short-term deposits is quite similar to the composition of the entrained C4 meal particles; while the build-up of mature deposits is influenced greatly by local temperature gradients and long-term fluctuations. I.e. in zones with locally lower temperatures, such as cold area of calciner walls (< ∼850 °C), heterogeneous condensation and/or thermophoresis of KCl from the high-temperature flue gas is facilitated.

Effect of Bilayer Thickness and Bias Potential on the Structure and Properties of (TiZr/Nb)N Multilayer Coatings as a Result of Arc-PVD Deposition.

This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, ε-NbN with a hexagonal structure, as well as with a small volume fraction of the ε-Ti2N and β-Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of ε-NbN and β-Nb2N nitrides. In all investigated systems obtained at -100 V and -200 V bias potentials, ε-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure.

Toward accurate density and interfacial tension modeling for carbon dioxide/water mixtures

Phase behavior of carbon dioxide/water binary mixtures plays an important role in various CO2-based industry processes. This work aims to screen a thermodynamic model out of a number of promising candidate models to capture the vapor–liquid equilibria, liquid–liquid equilibria, and phase densities of CO2/H2O mixtures. A comprehensive analysis reveals that Peng–Robinson equation of state (PR EOS) (Peng and Robinson 1976), Twu α function (Twu et al. 1991), Huron–Vidal mixing rule (Huron and Vidal 1979), and Abudour et al. (2013) volume translation model (Abudour et al. 2013) is the best model among the ones examined; it yields average absolute percentage errors of 5.49% and 2.90% in reproducing the experimental phase composition data and density data collected in the literature. After achieving the reliable modeling of phase compositions and densities, a new IFT correlation based on the aforementioned PR EOS model is proposed through a nonlinear regression of the measured IFT data collected from the literature over 278.15–477.59 K and 1.00–1200.96 bar. Although the newly proposed IFT correlation only slightly improves the prediction accuracy yielded by the refitted Chen and Yang (2019)’s correlation (Chen and Yang 2019), the proposed correlation avoids the inconsistent predictions present in Chen and Yang (2019)’s correlation and yields smooth IFT predictions.

Iron activity measurements and spinel-slag equilibria in alumina-bearing iron silicate slags

Alumina is a common substance deporting in copper smelting slags when various secondary copper fractions, e.g. e-scrap or WEEE, are used as feedstock as such or along with primary sulphide concentrates. Properties of iron-silicate slags at high alumina concentrations, in the iron-alumina spinel saturation, have been studied at 1300 °C by a high temperature equilibration-quenching method combined with EPMA (electron probe microanalysis) phase composition data from the polished sections. The equilibrations were performed in fixed oxygen activity with platinum or palladium powder, which dissolved iron from the slag and generated a heterogeneous equilibrium system, characterised by the general equilibrium criterium in isothermal and isobaric conditions, as.μalloy(Fe) = μslag(Fe) = μspinel(Fe).This criterium was used for measuring experimentally iron activities of molten silicate slags. The locations of the spinel-liquid slag tie-lines were also determined in the oxygen partial pressure range of 10−6–10−10 atm. A comparison with the recent critical thermodynamic assessments of the Fe–O–Al2O3 system indicates that the iron-alumina spinel-corundum phase boundary in silica-containing systems as a function of oxygen partial pressure is too steep and thus the assessed databases do not match with the experimental data of this study. The liquid slag domain from silica to iron oxide saturation is also smaller than expected earlier, as the spinel primary phase boundary locates at higher silica concentrations than e.g. obtained in the assessments of the Mtox database.

Systematic Investigations on Continuous Fluidized Bed Crystallization for Chiral Separation

A recently developed continuous enantioseparation process utilizing two coupled fluidized bed crystallizers is systematically investigated to identify essential correlations between different operation parameters and the corresponding process performance on the example of asparagine monohydrate. Based on liquid phase composition and product crystal size distribution data, it is proven that steady state operation is achieved reproducibly in a relatively short time. The process outputs at steady state are compared for different feed flow rates, supersaturations, and crystallization temperatures. It is shown that purities &gt;97% are achieved with productivities up to 40 g/L/h. The size distribution, which depends almost exclusively on the liquid flow rate, can be easily adjusted between 260 and 330 µm (mean size) with an almost constant standard deviation of ±55 µm.

BRUCITE-BASED MAGNESIUM PHOSPHATE BONDING AGENT, ITS ANALYSIS AND APPLICATION FOR PERICLASE SINTERING

Some results on magnesium phosphate binder obtained from natural brucite (mainly Mg(OH)2) and H3PO4 were discussed. Hereafter, it was named brucite phosphate (BPB). This binder then was used to the sintering of MgO (periclase). MgO is one of the most high-refractory materials and chemically stable to various aggressive mediums, so the aim was presented as actual. To determine the phase composition data on sample weight loss in different temperature intervals were compared. All weight losses were related to the multistage water moving away. Up to 140 °С it was the removal of crystalline hydrate water. Then monosubstituted magnesium hydrophosphate transformed into MgH2P2O7 and Mg2P4O12, that in principle was in accordance with literature data. Dehydration was accompanied with appropriate endothermal effects. There was a slight exothermal effect which could relate to a structure rearrangement (cyclization) of primary magnesium metaphosphates and/or some crystallization of anhydrous cyclophosphates from primarily obtained amorphous phase non-connected with a weight loss in the interval of 450-575 °С. At 500–1000 °С the phase composition remained constant that was in a good accordance with data obtained by other methods. By means of IR-spectroscopy, it was confirmed the formation of structure cycles composed from oxygen-phosphor tetrahedrons. To determine kinetics parameters of periclase sintering with BPB it was used a model being proposed that took the role of a physical consolidation and a chemical binding in the presence of binder into account under heating. The obtained parameters analysis showed that the forming conglomerate strength was provided with the sintering properly as well as with binder action; an estimated chemical factor contribution was maximal at low temperatures (1100-1200 °C). The activation energy value was practically identical to the activation energy of oxygen diffusion in MgO.

Thermodynamic model of fast pyrolysis bio-oil advanced distillation curves

Fast pyrolysis bio-oil (FPBO) is a complex organic liquid with over 1000 organic compounds. Therefore, little research exists on the prediction and modelling of liquid physicochemical properties and vapour-liquid phase behaviour. A thermodynamic model of the FPBO vapour-liquid equilibrium (VLE) in distillation will improve the understanding of bulk and FPBO fraction properties, and therefore, aid in the enhancement of FPBO for desired applications, such as condensation of pyrolysis vapours, fractionation, and evaporation during combustion. FPBO produced at 450 °C from softwood sawmill residues at a feed rate of 4 kg/h (~20 s residence time) in a pilot-scale auger reactor was distilled in an advanced distillation curve (ADC) apparatus at atmospheric pressure and at a vacuum of 5 kPa (abs). The ADC equipment allows for the data collection of true thermodynamic state points, including vapour phase composition data. UNIQUAC was the selected equation of states (EoS) to model FPBO distillation VLEs in a 20–flash series in VMGSim™. A surrogate mixture of water, 3,4,4′-biphenoltriol (pyrolytic lignin), inert solids, and multiple organic components was used to model and predict the VLE and consequently bulk physicochemical properties. It was found that GC-FID composition data (in area%), water content (Karl Fisher titration), distillation residue, and solid content were sufficient to inform the model (surrogate composition). This work improved the understanding of FPBO phase behaviour, composition, and bulk properties. The method allows for the identification of target components and fractions to enhance FPBO quality for desired applications.

Modification of a model for mixed hydrates to represent double cage occupancy

Gas hydrates are subject of current research work and are also important for several industrial applications. When transporting natural gases or oil through pipelines, the formation of gas hydrates and thus a blockage of the pipeline must be avoided. There is also a great interest to understand the thermophysical properties and the phase change behavior of hydrates during liquefaction processes of natural gases, for CO2 capture and sequestration (CCS) processes, and for CH4 and C2H6 hydrates, which can be found on the seabed or in permafrost soils as a potential energy source. In this work, the model for mixed gas hydrates (mixtures of water with more than one hydrate former), which has been introduced in a previous work [Fluid Phase Equilib. 459 (2018) 170–185] and is intended for the use in CCS relevant applications, is modified to take double cage occupancy into account. The three-phase equilibrium data can be reproduced up to high pressures at which N2, O2, and Ar are known to double occupy the hydrate cavities. The influence of double occupied hydrate cages and the improved reproduction of experimental phase equilibrium data at pressures at which double cage occupancy occurs are shown for pure hydrate and for mixed hydrate phase equilibrium and composition data. In case of mixed hydrates, comparisons are shown for synthetic air (N2+O2).

Phase Behavior of Heavy-Oil/Propane Mixtures

Summary The phase behavior of heavy-oil/propane mixtures was mapped from temperatures ranging from 20 to 180°C and pressures up to 10 MPa. Both vapor/liquid (VL1) and liquid/liquid (L1L2) regions were observed. Saturation pressures (VL1 boundary) were measured in a Jefri 100-cm3 pressure/volume/temperature (PVT) -cell and blind-cell apparatus. The propane content at which a light propane-rich phase and a heavy bitumen-rich (or pitch) phase formed (L1/L1L2 boundary) was visually determined with a high-pressure microscope (HPM) while titrating propane into the bitumen. High-pressure and high-temperature yield data were measured using a blind-cell apparatus. Here, yield is defined as the mass of the indicated component(s) in the pitch phase divided by the mass of bitumen in the feed. A procedure was developed and used to measure propane-rich-phase and pitch-phase compositions in a PVT cell. Pressure/temperature and pressure/composition phase diagrams were constructed from the saturation-pressure and pitch-phase-onset data. High-pressure micrographs demonstrated that, at lower temperatures and propane contents, the pitch phase appeared as glassy particles, whereas at higher propane contents and temperatures, it appeared as a liquid phase. Ternary diagrams were also constructed to present phase-composition data. The ability of a volume-translated Peng-Robinson cubic equation of state (CEOS) (Peng and Robinson 1976) to match the experimental measurements was explored. Two sets of binary-interaction parameters were tested: temperature-dependent binary-interaction parameters (SvdW) and composition-dependent binary-interaction parameters (CDvdW). Models derived from both types of binary-interaction parameters matched the saturation pressures and the L1L2 boundaries at one pressure but could not match the pressure dependency of the L1L2 boundary or the measured L1L2 phase compositions. The SvdW model could not match the yield data, whereas the CDvdW model matched yields at temperatures up to 90°C.

Phase behavior of bitumen and n-pentane

The phase boundaries for mixtures of n-pentane and bitumen were determined at temperatures from 21 to 280 °C and pressures up to 14 MPa. Both vapor-liquid equilibria and liquid-liquid (solvent-rich and asphaltene-rich phases) equilibria were observed for these mixtures. Saturation pressures (vapor-liquid boundary) were measured using both a PVT cell and a blind cell apparatus at temperatures ranging from 90 to 280 °C. The compositions at which a separate asphaltene-rich heavy phase is formed (asphaltene onset point or liquid-liquid boundary) were measured using a high pressure microscope apparatus for a temperature range of 20–180 °C and were extrapolated from asphaltene yield data at temperatures up to 250 °C.At low temperature, the asphaltene-rich heavy phase appears as dispersed glassy particles. However, at temperatures above approximately 140 °C, this heavy phase separates as a continuous liquid and; therefore, a sample of this phase can be isolated and collected. A PVT cell procedure was developed to collect and assay heavy liquid phases in order to determine the asphaltene yield and composition in terms of solvent, maltene, and C5-asphaltene (n-pentane insoluble asphaltenes) contents. A blind cell apparatus was also designed to measure C5-asphaltene yields for multiple samples simultaneously using a similar procedure.The asphaltene yield, (mass of C5-asphaltene partitioning to the heavy phase) was measured for a range of mixtures of bitumen and n-pentane with feed compositions from 50 to 90 mass % n-pentane at temperatures from 21 to 250 °C and pressures up to 13.8 MPa. Heavy phase compositions were measured for feed compositions of 59–72 mass % n-pentane at 180 °C and 4.8 MPa. The ability of a modified Peng-Robinson cubic equation-of-state model to predict the phase boundaries and the yield and phase composition data is assessed.

In Situ Neutron Scattering Study of Nanostructured PbTe-PbS Bulk Thermoelectric Material

Nanostructures play an important role in thermoelectric materials. Their thermal stability, such as phase change and evolution at elevated temperatures, is thus of great interest to the thermoelectric community. In this study, in situ neutron diffraction was used to examine the phase evolution of nanostructured bulk PbTe-PbS materials fabricated using hot pressing and pulsed electrical current sintering (PECS). The PbS second phase was observed in all samples in the as-pressed condition. The temperature dependent lattice parameter and phase composition data show an initial formation of PbS precipitates followed by a redissolution during heating. The redissolution process started around 570–600 K, and completed at approximately 780 K. During cooling, the PECS sample followed a reversible curve while the heating/cooling behavior of the hot pressed sample was irreversible.

Preparation and structural study of Mg1−x Zn x TiO3 ceramics and their dielectric properties from 1 Hz to 7.7 GHz

A series of Mg1−x Zn x TiO3, x = 0–0.5 (MZT0–MZT0.5) ceramics was synthesised and characterised. The dielectric properties of the samples in the frequency range of 1 Hz–7.7 GHz were explored using three different methods: a contacting electrode method, a parallel-plate method and a perturbed resonator method. The electrical properties in the space charge and dipolar polarisation frequency ranges are discussed in relation to the phase composition and microstructure data. Differences in the zinc substitution divided the dielectrics into two groups, namely MZT0–MZT0.2 and MZT0.3–MZT0.5, each with different amount of a main Mg1−x Zn x TiO3 solid solution phase and a secondary solid solution phase. Zinc substitution promoted the density of the ceramics, improved the purity of the main phase and increased the permittivity for frequencies up to 108 Hz, but reduced the permittivity in the microwave range. In the MZT0.3–MZT0.5 samples, for frequencies less than 1 MHz the quality (Q × f) factors were lower and log σ a.c, the AC conductivity, was higher than for the MZT0–MZT0.2 samples. Above 10 MHz, the (Q × f) factors and log σ a.c of the two groups were similar.

Measurements of solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K

Solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K were measured by the isothermal dissolution equilibrium method. The solubilities of salts and densities of saturated solutions in the ternary system were determined experimentally. The equilibrium solid phases were also determined by chemical analysis and X-ray powder diffraction. Using the experimental data, the phase diagram of the ternary system was obtained, which comprise one univariant curve and one stationary phase in crystallization filed of Na (Cl, Br). The ternary system was solid solution type. Density values in the equilibrium solution increase with an increase of the sodium bromide concentration while decrease with an increase of the sodium chloride concentration. The relationship equation of equilibrium liquid phase and the solid phase composition data were fitted with a regression equation.

Analytic Setup for Multicomponent High‐Pressure Phase Equilibria via Dual Online Gas Chromatography

AbstractA high‐pressure analytic phase equilibria setup, capable of operation at 150 °C and 30 MPa, was developed. The variable‐volume view cell contains two height‐adjustable samplers enabling simultaneous sampling from two phases. Concurrent analysis of both samples was performed with dual online gas chromatography (GC). The GC comprises two inlets, four columns, two switch valves, and three detectors, arranged in parallel pathways. Quantitative detector calibrations were used. The setup was validated by sampling from a one‐phase ternary of known composition, and comparison with binary and ternary literature data. The setup produces accurate phase composition data for supercritical systems and is well‐suited to handle mixture constituents ranging from volatile gases to mid‐length hydrocarbons.

Phase equilibria study of K–O–Si system in equilibrium with air

Abstract The binary phase diagram in the silica rich corner of K–O–Si system in equilibrium with air has been studied at temperatures between 770 °C and 1500 °C. Equilibration at high temperature in an appropriate containment material of pure silica, followed by rapid quenching and measurement of phase structures and assemblages using SEM-EDS confirmed by an electron probe X-ray microanalysis technique, was carried out to obtain the phase composition data at equilibrium. The results are in good agreement with previous experimental data and close to the earlier assessed phase equilibria at silica saturation.

Solid–Liquid Equilibria in the Ternary System KCl–KBr–H2O at 348 K

Phase equilibria in the ternary system KCl–KBr–H2O at 348 K were studied by the isothermal solution dissolution equilibrium method. The solubilities of salts and densities of saturated solutions in the ternary system were determined experimentally. The equilibrium solid phases were also determined by chemical analysis and X-ray powder diffraction. Using the experimental data, the phase diagram of the ternary system was obtained, which comprises one univariant curve and one stationary phase in the crystallization field of K(Cl,Br). The ternary system was a solid solution type. The density transformation rules were discussed simply, and the relationship equations of equilibrium liquid phase and the solid phase composition data were fitted with a cubic equation.

Physically Based Equation for Phase Composition Curve of Frozen Soils

The relationship between unfrozen water content (or saturation in freezing and thawing) and temperature, which is referred to as the phase composition curve in frozen soils, is a fundamental relationship in cold regions engineering. Because of the lack of a physical basis, there have been only empirical equations for this relationship. This study investigated the mechanisms underlying the phase composition curve. A detailed physical basis was established on the basis of the soil freezing characteristic curve, the Clapeyron equation, and the bundle of cylindrical capillary model. From this physical basis, a closed-form equation was developed for the formulation and prediction of this curve. This physically based equation quantifies the unique correlation between saturation and temperature in frozen soils and takes various factors into account, such as the soil saturation under unfrozen conditions and the lowest temperature used in experiments. The equation was validated with phase composition data measured with a thermal–time domain reflectometry sensor. In addition, the flexibility of the equation and its excellent applicability in various soils with a wide range of properties, in large temperature ranges, and in both freezing and thawing processes (hysteresis) were proved with reported data.

Isothermal vapor–liquid equilibria and excess Gibbs free energies in some binary nitroalkane + chloroalkane mixtures at temperatures from 298.15 K to 318.15 K

The vapor pressures of binary mixtures of cloroalkane (1-chlorobutane, 1-chloropentane)+nitromethane or nitroethane were measured at temperatures between 298.15K and 318.15K. The vapor pressures vs. liquid phase composition data have been used to calculate the activity coefficients of the two components, and the excess molar Gibbs energies GE for the mixtures, using Barker's method. Redlich–Kister, Wilson, NRTL and UNIQUAC equations, taking into account the vapor phase imperfection in terms of the 2-nd virial coefficient, have represented the GE values. No significant difference between GE values obtained with these equations has been observed. The results indicate that all the systems show positive deviations from Raoult's law. The experimental VLE data were analyzed in terms of the modified UNIFAC (Dortmund) model.

A thermodynamic model for predicting mineral reactivity in supercritical carbon dioxide: I. Phase behavior of carbon dioxide–water–chloride salt systems across the H2O-rich to the CO2-rich regions

Phase equilibria in mixtures containing carbon dioxide, water, and chloride salts have been investigated using a combination of solubility measurements and thermodynamic modeling. The solubility of water in the CO2-rich phase of ternary mixtures of CO2, H2O and NaCl or CaCl2 was determined, using near infrared spectroscopy, at 90atm and 40 to 100°C. These measurements fill a gap in the experimental database for CO2–water–salt systems, for which phase composition data have been available only for the H2O-rich phases. A thermodynamic model for CO2–water–salt systems has been constructed on the basis of the previously developed Mixed-Solvent Electrolyte (MSE) framework, which is capable of modeling aqueous solutions over broad ranges of temperature and pressure, is valid to high electrolyte concentrations, treats mixed-phase systems (with both scCO2 and water present) and can predict the thermodynamic properties of dry and partially water-saturated supercritical CO2 over broad ranges of temperature and pressure. Within the MSE framework the standard-state properties are calculated from the Helgeson–Kirkham–Flowers equation of state whereas the excess Gibbs energy includes a long-range electrostatic interaction term expressed by a Pitzer–Debye–Hückel equation, a virial coefficient-type term for interactions between ions and a short-range term for interactions involving neutral molecules. The parameters of the MSE model have been evaluated using literature data for both the H2O-rich and CO2-rich phases in the CO2–H2O binary and for the H2O-rich phase in the CO2–H2O–NaCl/KCl/CaCl2/MgCl2 ternary and multicompontent systems. The model accurately represents the properties of these systems at temperatures from 0°C to 300°C and pressures up to ~4000atm. Further, the solubilities of H2O in CO2-rich phases that are predicted by the model are in agreement with the new measurements for the CO2–H2O–NaCl and CO2–H2O–CaCl2 systems even though the new data were not used in the parameterization of the model. Thus, the model can be used to predict the effect of various salts on the water content and water activity in CO2-rich phases on the basis of parameters determined from the properties of aqueous systems. Given the importance of water activity in CO2-rich phases for mineral reactivity, the model can be used as a foundation for predicting mineral transformations across the entire CO2/H2O composition range from aqueous solution to anhydrous scCO2. An example application using the model is presented which involves the transformation of forsterite to nesquehonite as a function of temperature and water content in the CO2-rich phase.