A New Predictive Group-Contribution Ideal-Heat-Capacity Model and Its Influence on Second-Derivative Properties Calculated Using a Free-Energy Equation of State

2020 ◽  
Vol 65 (12) ◽  
pp. 5809-5829
Author(s):  
Pierre J. Walker ◽  
Andrew J. Haslam
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
Group Contribution ◽  
Second Derivative ◽  
Capacity Model

Explicit Gibbs free energy equation of state for solids

2008 ◽  
Vol 69 (8) ◽  
pp. 1912-1922 ◽  
Author(s):  
Eli Brosh ◽  
Roni Z. Shneck ◽  
Guy Makov
Keyword(s):  
Free Energy ◽  
Equation Of State ◽  
Gibbs Free Energy ◽  
Energy Equation

scholarly journals Method for constructing the fundamental equation of state that takes into account the peculiarities of the substance behaviour in a wide vicinity of the critical point

2021 ◽  
Vol 2057 (1) ◽  
pp. 012112
Author(s):  
S V Rykov ◽  
I V Kudryavtseva
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Equation Of State ◽  
Critical Point ◽  
Fundamental Equation ◽  
Virial Coefficients ◽  
Phenomenological Theory ◽  
Phase Region ◽  
Scale Functions ◽  
Fundamental Equation Of State

Abstract On the basis of the phenomenological theory of the critical point and the Benedek hypothesis, an expression for the Helmholtz free energy F with scale functions in the density-temperature variables has been developed. The proposed free energy equation has been tested on the example of constructing the fundamental equation of state of 2,3,3,3-tetrafluoropropene (R1234yf). By comparison with the known experimental data on the equilibrium properties of R1234yf – density and pressure on the phase equilibrium line, p-ρ-T-data in the single-phase region, the second and third virial coefficients, isochoric heat capacity, isobaric heat capacity and the sound velocity – the operating range of the equation of state of R1234yf has been established according to temperature from 220 K to 420 K and pressure up to 20 MPa.

scholarly journals Helmholtz Free Energy Equation of State for 3He–4He Mixtures at Temperatures Above 2.17 K

2021 ◽  
Vol 50 (4) ◽  
pp. 043102
Author(s):  
Changzhao Pan ◽  
Haiyang Zhang ◽  
Gérard Rouillé ◽  
Bo Gao ◽  
Laurent Pitre
Keyword(s):  
Free Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
Helmholtz Free Energy

Gibbs Free Energy Equation of State for Solid Methane from 21 to 300 K and up to 5000 MPa

2021 ◽  
Vol 66 (2) ◽  
pp. 1157-1171
Author(s):  
Paolo Stringari ◽  
Marco Campestrini ◽  
Salem Hoceini ◽  
Dyhia Atig
Keyword(s):  
Free Energy ◽  
Equation Of State ◽  
Gibbs Free Energy ◽  
Energy Equation ◽  
Solid Methane

scholarly journals Calculation of thermodynamic properties of mixtures in two-phase equilibrium

2021 ◽  
Vol 2039 (1) ◽  
pp. 012016
Author(s):  
Taiming Luo ◽  
A Yu Chirkov
Keyword(s):  
Free Energy ◽  
Phase Equilibrium ◽  
Equation Of State ◽  
Thermodynamic Properties ◽  
Energy Equation ◽  
Helmholtz Free Energy ◽  
High Accuracy ◽  
Liquid Equilibrium ◽  
Two Phase ◽  
Vapor Liquid Equilibrium

Abstract Thermodynamic properties of mixtures in vapor-liquid equilibrium (VLE) were studied. Thermodynamic properties of the methane-ethane mixtures in VLE were calculated with highly accurate Helmholtz free energy equation of state GERG-2008, simplified GERG-2008 and common cubic PR equation of state (EOS). Results show that GERG-2008 has high accuracy in VLE calculations. However, simplified GERG-2008 and PR-EOS both work unsatisfactorily in VLE calculations.

Helmholtz free energy equation of state for propane and R134a binary mixture

2018 ◽  
Vol 89 ◽  
pp. 1-10 ◽  
Author(s):  
Haiyang Zhang ◽  
Bo Gao ◽  
Wei Wu ◽  
Huiya Li ◽  
Quan Zhong ◽  
...  
Keyword(s):  
Free Energy ◽  
Equation Of State ◽  
Binary Mixture ◽  
Energy Equation ◽  
Helmholtz Free Energy

Thermodynamic Property Calculation in Vapor-Liquid Equilibrium for Multicomponent Mixtures using Highly Accurate Helmholtz Free Energy Equation of State

2021 ◽  
pp. 108-121
Author(s):  
T. Luo ◽  
A.Yu. Chirkov
Keyword(s):  
Free Energy ◽  
Equation Of State ◽  
Thermodynamic Properties ◽  
Energy Equation ◽  
Helmholtz Free Energy ◽  
Multicomponent Mixtures ◽  
Liquid Equilibrium ◽  
Equilibrium Calculation ◽  
Vapor Liquid Equilibrium ◽  
Vapor Liquid

Thermodynamic properties of multicomponent mixtures in phase equilibrium were studied. The tangent plane criterion was used for stability analysis, and the Gibbs energy minimization was employed for phase equilibrium calculation when the successive substitution didn't converge. Thermodynamic properties of a 12-component natural gas mixture in vapor-liquid equilibrium were calculated with highly accurate Helmholtz free energy equation of state GERG--2008, simplified GERG--2008 and common cubic Peng --- Robinson (PR) equation of state. Results show that in vapor-liquid equilibrium, GERG--2008 has high accuracy and works better than simplified GERG--2008 and PR-equation of state. Simplified GERG--2008 and PR-equation of state both work unsatisfactorily in vapor-liquid equilibrium calculation, especially near the saturation zone. The deviation function in GERG--2008 can significantly affect the accuracy of GERG--2008 when calculating thermodynamic properties of mixtures in vapor-liquid equilibrium

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