High-pressure fluid-phase equilibria: Experimental methods and systems investigated (2000-2004)

Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H^+, Li^+, Na^+, K^+, NH^+_4, Mg^(2+), Ca^(2+), Cl^−, Br^−, NO^−_3, HSO^−_4, and SO^(2−)_4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CH_n and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

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A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients

Peng-Robinson equation of state: 40 years through cubics

On the preferential solvation of drugs and PAHs in binary solvent mixtures

The speed of sound and density of mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with methanol, ethanol, 1-propanol, and water, as well as of the pure components have been experimentally measured over the whole range of compositions at T = (278.15 to 338.15) K and atmospheric pressure. From these experimental data, the excess molar volume, excess isentropic compressibility, and excess speed of sound have been calculated and fitted to an extended version of the Redlich−Kister equation, which takes into account the dependence on composition and temperature simultaneously. The Prigogine−Flory−Patterson theory has also been used to explain the behavior of these systems.

Volumetric and Ultrasonic Studies of 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate Ionic Liquid with Methanol, Ethanol, 1-Propanol, and Water at Several Temperatures.

The gas−liquid solubility of hydrogen in methanol, ethanol, 1-propanol, and 1-butanol at pressures in the range 3.6 to 10 MPa and at temperatures in the range 298.15 to 525.15 K has been measured in an autoclave type phase equilibrium apparatus using the total pressure method. Pseudo-Henry's law constants, , were calculated. The solubility of hydrogen increases with increasing temperature and pressure for all solvents used, and it also increases as the carbon chain length of the alcohol molecule increases.

Gas−Liquid Solubility of Hydrogen in n-Alcohols (1 ⩽ n ⩽ 4) at Pressures from 3.6 MPa to 10 MPa and Temperatures from 298.15 K to 525.15 K

Solubility of methane and carbon dioxide in ethylene glycol at pressures up to 14 MPa and temperatures ranging from (303 to 423) K

Thermodynamics of binary liquid mixtures: application of the Prigogine–Flory–Patterson theory to excess molar volumes of acetonitrile+1-alkanol systems

The numerical simulation of gas dispersion is of great importance in various areas of engineering such as optimisation, synthesis of chemical process, petroleum industry and process safety. The OpenFOAM (Open Field Operation and Manipulation) code is a free and open source computational fluid dynamics (CFD) program. The current research is focused on the development and customisation of a computational tool for handling gas dispersion of heavy gases, such a LNG and CO 2 . The novel CFD tool relies on OpenFOAM framework. The core of the work is based on the OpenFOAM solver rhoReactingBuoyantFoam to handle gas dispersion. A series of CFD simulations has been performed for methane and CO 2 . The source term of the former is modelled by HSM (Hybrid Switch Model). The model comprises contribution from HEM (Homogeneous Equilibrium Model) approach, frozen model and non-equilibrium model for CO 2 leak. The novel approach switches between equilibrium and non-equilibrium conditions based on the meta-stable parameter on the grounds of thermodynamics and experimental observations. Good agreement with experimental data is observed. Numerical findings for methane leakage from the proposed CFD tool are compared with experimental data and FLACS. Good agreement is observed.

An alternative CFD tool for gas dispersion modelling of heavy gas

A new still to measure the salt effect on the vapor-liquid equilibrium at low pressures was developed. It is of the recirculating type, allowing the recirculation of both phases and the determination of its composition. The still was tested with the system ethanol-water-potassium acetate at different mole fractions of salt at 101.33 kPa

A.Z. Francesconi

Papers

Gas−Liquid Solubility of Hydrogen in n-Alcohols (1 ⩽ n ⩽ 4) at Pressures from 3.6 MPa to 10 MPa and Temperatures from 298.15 K to 525.15 K

Solubility of methane and carbon dioxide in ethylene glycol at pressures up to 14 MPa and temperatures ranging from (303 to 423) K

Thermodynamics of binary liquid mixtures: application of the Prigogine–Flory–Patterson theory to excess molar volumes of acetonitrile+1-alkanol systems

An alternative CFD tool for gas dispersion modelling of heavy gas

Salt effect on phase equilibria by a recirculating still