Van der Waals Mixing Rules for Cubic Equations of State

1987 ◽  
pp. 101-114 ◽  
Author(s):  
E. H. Benmekki ◽  
T. Y. Kwak ◽  
G. A. Mansoori
Keyword(s):  
Equations Of State ◽  
Van Der Waals ◽  
Mixing Rules

scholarly journals A thermodynamic approach for correlating the solubility of drug compounds in supercritical CO2 based on Peng-Robinson and Soave-Redlich-Kwong equations of state coupled with van der Waals mixing rules

2019 ◽  
Vol 84 (10) ◽  
pp. 1169-1182
Author(s):  
Narjes Setoodeh ◽  
Parviz Darvishi ◽  
Abolhasan Ameri
Keyword(s):  
Supercritical Co2 ◽  
Equations Of State ◽  
Numerical Technique ◽  
Van Der Waals ◽  
Pharmaceutical Compounds ◽  
Thermodynamic Approach ◽  
Binary Interaction ◽  
Mixing Rules ◽  
Different Temperatures ◽  
Better Than

In the present study, the effect of equations of state and mixing rules in a thermodynamic approach has been investigated for the correlation of the solubility of four new solid pharmaceutical compounds, namely, benzamide, cetirizine, metaxalone and niflumic acid in supercritical CO2 at different temperatures and pressures. Two equations of state, the Peng?Robinson (PR) and Soave?Redlich?Kwong (SRK), coupled with mixing rules of one-parameter van der Waals (vdW1) and two-parameter van der Waals (vdW2) were used, where the binary interaction parameters for these sets of equations were evaluated. The approach correlations and the robustness of the numerical technique were validated with the experimental data previously reported for these compounds at different temperatures and pressures. The calculated average absolute relative deviations (AARD) were 7.51 and 5.31 % for PR/vdW1 and PR/ /vdW2 couples, and 11.05 and 10.24 % for SRK/vdW1 and SRK/vdW2 couples, respectively. It was also found that the PR equation of state results in modeling performance better than the SRK equation, and the vdW2 mixing rule better than the vdW1 one. These results obviously demonstrate that the combined approach used in this study is applicable for correlation of solid solubilities of some pharmaceutical compounds in supercritical CO2. Additionally, a semiempirical correlation is proposed for estimating the solubility of drug solids in supercritical CO2 as a function of pressure and temperature.

Properties of Refrigerants from Cubic Equations of State

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Viorel Feroiu ◽  
Dan Geana ◽  
Catinca Secuianu
Keyword(s):  
Experimental Data ◽  
Vapor Pressure ◽  
Equations Of State ◽  
Ternary Mixtures ◽  
Volumetric Properties ◽  
Mixing Rules ◽  
Saturation Curve ◽  
Equilibrium Thermodynamic ◽  
Liquid Equilibrium ◽  
Binary And Ternary Mixtures

Vapour � liquid equilibrium, thermodynamic and volumetric properties were predicted for three pure hydrofluorocarbons: difluoromethane (R32), pentafluoroethane (R125) and 1,1,1,2 � tetrafluoroethane (R134a) as well as for binary and ternary mixtures of these refrigerants. Three cubic equations of state GEOS3C, SRK (Soave � Redlich � Kwong) and PR (Peng � Robinson) were used. A wide comparison with literature experimental data was made. For the refrigerant mixtures, classical van der Waals mixing rules without interaction parameters were used. The GEOS3C equation, with three parameters estimated by matching several points on the saturation curve (vapor pressure and corresponding liquid volumes), compares favorably to other equations in literature, being simple enough for applications.

scholarly journals Van der Waals-like Equations of State. I. Application to Pure Liquids

1981 ◽  
Vol 13 (11) ◽  
pp. 993-1002 ◽  
Author(s):  
Koichi Fujisawa ◽  
Tomoo Shiomi ◽  
Fumiyuki Hamada ◽  
Akio Nakajima
Keyword(s):  
Equations Of State ◽  
Van Der Waals

Phase Transitions

2019 ◽  
pp. 205-222
Author(s):  
Robert H. Swendsen
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
Phase Transitions ◽  
Helmholtz Free Energy ◽  
Equations Of State ◽  
Van Der Waals ◽  
Ideal Gas ◽  
Phase Rule ◽  
Clapeyron Equation ◽  
Maxwell Construction

Phase transitions are introduced using the van der Waals gas as an example. The equations of state are derived from the Helmholtz free energy of the ideal gas. The behavior of this model is analyzed, and an instability leads to a liquid-gas phase transition. The Maxwell construction for the pressure at which a phase transition occurs is derived. The effect of phase transition on the Gibbs free energy and Helmholtz free energy is shown. Latent heat is defined, and the Clausius–Clapeyron equation is derived. Gibbs' phase rule is derived and illustrated.

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