scholarly journals MODELING OF THERMODYNAMIC PROPERTIES AND PHASE EQUILIBRIUM IN SYSTEM OF LiCl – H2O WITHIN FRAME OF PITZER MODEL

2018 ◽  
Vol 61 (3) ◽  
pp. 21
Author(s):  
Svetlana E. Pratskova
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Thermodynamic Properties ◽  
Lithium Chloride ◽  
Osmotic Coefficient ◽  
Eutectic Point ◽  
Pitzer Model ◽  
Free Gibbs Energy ◽  
Pitzer's Model ◽  
Pitzer’S Model

Lithium chloride is used as a solid electrolyte in chemical sources of current, organic synthesis, pyrotechnics and as a desiccant. To describe the thermodynamic properties of aqueous electrolyte solutions, the Pitzer’s model is most widely used. Model equations are simple and contain a small number of variable parameters that have a certain physical meaning. They are linear combinations of virial coefficients in the expansion of the excess free Gibbs energy of the solution of the number of moles of ions. The results of thermodynamic modeling of the LiCl - H2O system within the frame of this model are presented in the article. Equations for calculating the average ionic coefficient of activity for the component of the LiCl system and the osmotic coefficient of water are derived. The energy parameters of the model are calculated taking into account the experimental data on the osmotic coefficient of water Ф on the composition of the solution at 25 °C and on the temperature for the LiCl - H2O system. To verify the adequacy of the Pitzer’s model, the inverse problem was solved, i.e. the values of the osmotic coefficient of water and the average ionic coefficient of the solution composition were calculated. The calculated values are in good agreement with the experimental data. The values of the standard Gibbs energies for the formation of crystalline hydrates LiC∙H2O, LiCl∙2H2O are determined. A double phase diagram of LiCl - H2O is constructed. On the calculated diagram, there is a eutectic point with coordinates of 25.3 wt.% LiCl, t = -80 °C and two peritectics of 48.2 wt. % LiCl, t = 50 °C; 56.5 wt. % LiCl, t = 102 °C. The excess partial molar enthalpies and entropies of the solution components were calculated. As follows from the data obtained, aqueous solutions of lithium chloride are formed with heat absorption, the system is stabilized by increasing entropy. The solution experiences positive deviations from ideality.Forcitation:Pratskova S.E. modeling of thermodynamic properties and phase equilibrium in system of LiCl – H2O within frame of pitzer model. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 21-25

scholarly journals Thermodynamic Assessment Of The Bi-In-Zn System

2015 ◽  
Vol 60 (2) ◽  
pp. 567-575
Author(s):  
B. Onderka ◽  
A. Dębski ◽  
W. Gąsior
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Thermodynamic Properties ◽  
Phase Equilibria ◽  
Thermodynamic Assessment ◽  
Thermodynamic Description ◽  
Thermal Equilibration ◽  
Heating And Cooling ◽  
Coexisting Phases ◽  
Equilibrium Calculations

Abstract A thermodynamic description of the entire ternary Bi-In-Zn system was obtained by the CALPHAD modelling of the Gibbs energy of the liquid phase. The experimental data on the phase equilibria and the thermodynamic properties published and complemented by the authors’ own experiments were taken into account. In order to verify the phase equilibria in the Bi-In-Zn system, 15 different samples were studied in the temperature range of 300-900 K by the DTA technique during heating and cooling cycles. Coexisting phases and their composition were analyzed by the SEM and EDX techniques for 9 distinct samples after their thermal equilibration at 373 K and 473 K. Assessment and selected phase equilibrium calculations were performed with ThermoCalc and Pandat softwares, and compared with experimental data. The obtained results reproduce well the experimental data on both the phase equilibria and the thermodynamic properties in the optimized system.

Thermodynamic Database of the Phase Diagrams in the Au-RE Binary Systems

2016 ◽  
Vol 850 ◽  
pp. 433-438 ◽  
Author(s):  
Yu Heng Li ◽  
Fei Xu ◽  
Peng Wu Yang ◽  
Jia Lian Li ◽  
Lu Jiang Zhou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Thermodynamic Properties ◽  
Phase Diagrams ◽  
Binary Systems ◽  
Thermodynamic Database ◽  
Free Energies ◽  
Significant Information ◽  
Lead Free Solders ◽  
Further Development

The thermodynamic database has been developed for Au-RE binary systems. Based on the experimental data including thermodynamic properties and phase equilibrium, the thermodynamic assessments of phase diagrams in the Au-RE (RE: Nd, Dy, Yb, Gd, Tb, Sm, Lu) binary systems were carried out by using the CALPHAD (Calculation of Phase Diagrams) method. The Gibbs free energies of the solution phases were described by substitutional solution model, and all of the intermetallic compounds were described by sublattice models. The calculated phase diagrams are congruent with the available experimental data. Combined with the assessed Au-RE (RE: La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) binary systems, the thermodynamic database of Au-RE binary systems has been developed, and some significant information of thermodynamic properties and phase equilibrium could be calculated, which is important for the further development of Sn-Au-RE high-temperature lead-free solders.

scholarly journals Homogenisation Efficiency Assessed with Microstructure Analysis and Hardness Measurements in the EN AW 2011 Aluminium Alloy

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1211
Author(s):  
Maja Vončina ◽  
Aleš Nagode ◽  
Jožef Medved ◽  
Irena Paulin ◽  
Borut Žužek ◽  
...  
Keyword(s):  
Experimental Data ◽  
Image Analysis ◽  
Phase Equilibrium ◽  
Aluminium Alloy ◽  
Phase Formation ◽  
Aluminium Alloys ◽  
Eutectic Phase ◽  
The Matrix ◽  
Equilibrium Solidification ◽  
Homogenisation Process

When extruding the casted rods from EN AW 2011 aluminium alloys, not only their homogenized structure, but also their extrudable properties were significantly influenced by the hardness of the alloy. In this study, the object of investigations was the EN AW 2011 aluminium alloy, and the effect of homogenisation time on hardness was investigated. First, homogenisation was carried out at 520 °C for different times, imitating industrial conditions. After homogenisation, the samples were analysed by hardness measurements and further characterised by microscopy and image analysis to verify the influence of homogenisation on the resulting microstructural constituents. In addition, non-equilibrium solidification was simulated using the program Thermo-Calc and phase formation during solidification was investigated. The homogenisation process enabled more rounded shape of the Al2Cu eutectic phase, equilibrium formation of the phases, and the precipitation in the matrix, leading to a significant increase in the hardness of the EN AW 2011 aluminium alloy. The experimental data revealed a suitable homogenisation time of 4–6 h at a temperature of 520 °C, enabling optimal extrusion properties.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

Fuel Droplet Evaporation in a Supercritical Environment

2002 ◽  
Vol 124 (4) ◽  
pp. 762-770 ◽  
Author(s):  
G. S. Zhu ◽  
S. K. Aggarwal
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Ambient Pressure ◽  
Droplet Surface ◽  
Fuel Vapor ◽  
Phase Solubility ◽  
Liquid Density ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Wide Range

This paper reports a numerical investigation of the transcritical droplet vaporization phenomena. The simulation is based on the time-dependent conservation equations for liquid and gas phases, pressure-dependent variable thermophysical properties, and a detailed treatment of liquid-vapor phase equilibrium at the droplet surface. The numerical solution of the two-phase equations employs an arbitrary Eulerian-Lagrangian, explicit-implicit method with a dynamically adaptive mesh. Three different equations of state (EOS), namely the Redlich-Kwong (RK), the Peng-Robinson (PR), and Soave-Redlich-Kwong (SRK) EOS, are employed to represent phase equilibrium at the droplet surface. In addition, two different methods are used to determine the liquid density. Results indicate that the predictions of RK-EOS are significantly different from those obtained by using the RK-EOS and SRK-EOS. For the phase-equilibrium of n-heptane-nitrogen system, the RK-EOS predicts higher liquid-phase solubility of nitrogen, higher fuel vapor concentration, lower critical-mixing-state temperature, and lower enthalpy of vaporization. As a consequence, it significantly overpredicts droplet vaporization rates, and underpredicts droplet lifetimes compared to those predicted by PR and SRK-EOS. In contrast, predictions using the PR-EOS and SRK-EOS show excellent agreement with each other and with experimental data over a wide range of conditions. A detailed investigation of the transcritical droplet vaporization phenomena indicates that at low to moderate ambient temperatures, the droplet lifetime first increases and then decreases as the ambient pressure is increased. At high ambient temperatures, however, the droplet lifetime decreases monotonically with pressure. This behavior is in accord with the reported experimental data.

Sign in / Sign up

Export Citation Format

Share Document