scholarly journals A New Method to Calculate the Pure Component Parameters of Any Two-Parameter Equation of State

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Isam H. Aljundi
Keyword(s):  
Equation Of State ◽  
Equations Of State ◽  
Saturated Vapor ◽  
Pure Component ◽  
New Method ◽  
Average Deviation ◽  
Cubic Equation ◽  
Parameter Equation ◽  
Temperature Dependences ◽  
Two Parameter

Reliable equations of state are very important in the design of refrigeration cycles, since thermodynamic properties can be calculated by simple differentiation. In this paper, a new method to calculate the parameters of any two-parameter equation of state is presented. The method is based on the use of Clapeyron equation and the experimental PVT data. This method was tested on a newly developed cubic equation of state and proved to be simple and fast. Results showed orders of magnitude enhancement in prediction of the saturated vapor pressure even near the critical region. The Percent Absolute Average Deviation (%AAD) was always less than 0.1 in the studied cases. It also showed that the parameters calculated using the original equation deviate strongly from the “experimental” values as the temperature decreases below the critical point. This method can be used to redefine the temperature dependences of these parameters and develop new mixing rules for the mixtures.

scholarly journals A New Four-Parameter Cubic Equation of State for Predicting Fluid Phase Behavior

2019 ◽  
Author(s):  
zhiren he
Keyword(s):  
Heat Capacity ◽  
Equation Of State ◽  
Vapor Pressure ◽  
Saturated Vapor ◽  
Liquid Density ◽  
Saturated Liquid ◽  
Cubic Equation ◽  
Liquid Heat ◽  
Entropy Of Vaporization ◽  
Saturated Liquid Density

<p>A new four-parameter cubic equation of state (EoS) is generated by incorporating the critical compressibility factor (Z<sub>c</sub>) apart from the critical pressure (P<sub>c</sub>) and temperature (T<sub>c</sub>). One free parameter in the denominator of the attractive term and two parameters in the alpha function are adjusted using the experimental data of saturated liquid density, vapor pressure, and isobaric liquid heat capacity of 48 components including hydrocarbons and non-hydrocarbons. Applying this equation of state, saturated liquid density, saturated vapor density, and vapor pressure of pure components are accurately reproduced compared with experimental values. Furthermore, the predicted properties including derivatives of alpha function, such as enthalpy of vaporization, entropy of vaporization and isobaric heat capacity of liquid, also have decent accuracy. The global average absolute relative deviation (AAD) of saturated liquid density, saturated vapor density, saturated vapor pressure, enthalpy of vaporization, entropy of vaporization, and isobaric heat capacity of liquid in a wide reduced temperature (Tr) range of subcritical region reproduced by this work are 4.33%, 4.18%, 3.19%, 2.26%, 2.27%, and 5.82%, respectively. Substantial improvement has been achieved for the isobaric liquid heat capacity calculation.</p>

Can we safely predict solvation Gibbs energies of pure and mixed solutes with a cubic equation of state?

2019 ◽  
Vol 91 (8) ◽  
pp. 1295-1307 ◽  
Author(s):  
Edouard Moine ◽  
Romain Privat ◽  
Jean-Noël Jaubert ◽  
Baptiste Sirjean ◽  
Nefeli Novak ◽  
...  
Keyword(s):  
Equation Of State ◽  
Binary Data ◽  
Chemical Potential ◽  
Pure Component ◽  
Binary Interaction ◽  
Absolute Deviation ◽  
Practical Applications ◽  
Cubic Equation Of State ◽  
Cubic Equation ◽  
Gibbs Energies

Abstract Solvation Gibbs energies are basically defined as a chemical potential change when transferring a fixed molecule from a perfect gas to a real liquid mixture. This quantity is of special interest for many practical applications as it quantifies the degree of affinity of a solute for its solvent. Few methods are currently available in the literature for the prediction of solvation Gibbs energies. In this article, a new approach is proposed: the use of a predictive cubic equation of state (EoS). The UMR-PRU (Universal Mixing Rule Peng-Robinson UNIFAC) EoS has been selected for its known capacity to semi-predict behaviors of complex systems including polar and associating compounds (by semi-prediction, it is meant that the EoS predicts binary interaction parameters but requires pure-component properties as input parameters). UMR-PRU predictions have been compared to experimental data extracted from the extensive CompSol database (containing around 22 000 pure component data and 70 000 binary data). Accurate predictions were obtained (a mean absolute deviation of 0.36 kcal/mol was obtained for all the binary data). Finally, when using a fully-predictive approach (i.e. pure-component EoS parameters are predicted from group-contribution methods), the prediction accuracy is roughly preserved.

EMPIRICAL TWO-PARAMETER MIXING RULES FOR A CUBIC EQUATION-OF-STATE

1987 ◽  
Vol 59 (1-6) ◽  
pp. 259-275 ◽  
Author(s):  
R.S. MOHAMED ◽  
R.M. ENICK ◽  
P.G. BENDALE ◽  
G.D. HOLDER
Keyword(s):  
Equation Of State ◽  
Mixing Rules ◽  
Cubic Equation Of State ◽  
Cubic Equation ◽  
Two Parameter

scholarly journals A MultiScale Gibbs-Helmholtz Constrained Cubic Equation of State

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Angelo Lucia
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Internal Energy ◽  
Equations Of State ◽  
Energy Parameter ◽  
New Approach ◽  
Cubic Equation Of State ◽  
Cubic Equation ◽  
Dynamics Simulations

This paper presents a radically new approach to cubic equations of state (EOS) in which the Gibbs-Helmholtz equation is used to constrain the attraction or energy parameter, a. The resulting expressions for for pure components and for mixtures contain internal energy departure functions and completely avoid the need to use empirical expressions like the Soave alpha function. Our approach also provides a novel and thermodynamically rigorous mixing rule for . When the internal energy departure function is computed using Monte Carlo or molecular dynamics simulations as a function of current bulk phase conditions, the resulting EOS is a multiscale equation of state. The proposed new Gibbs-Helmholtz constrained (GHC) cubic equation of state is used to predict liquid densities at high pressure and validated using experimental data from literature. Numerical results clearly show that the GHC EOS provides fast and accurate computation of liquid densities at high pressure, which are needed in the determination of gas hydrate equilibria.

scholarly journals A New Four-Parameter Cubic Equation of State for Predicting Fluid Phase Behavior

2019 ◽  
Author(s):  
zhiren he
Keyword(s):  
Heat Capacity ◽  
Equation Of State ◽  
Vapor Pressure ◽  
Saturated Vapor ◽  
Liquid Density ◽  
Saturated Liquid ◽  
Cubic Equation ◽  
Liquid Heat ◽  
Entropy Of Vaporization ◽  
Saturated Liquid Density

<p>A new four-parameter cubic equation of state (EoS) is generated by incorporating the critical compressibility factor (Z<sub>c</sub>) apart from the critical pressure (P<sub>c</sub>) and temperature (T<sub>c</sub>). One free parameter in the denominator of the attractive term and two parameters in the alpha function are adjusted using the experimental data of saturated liquid density, vapor pressure, and isobaric liquid heat capacity of 48 components including hydrocarbons and non-hydrocarbons. Applying this equation of state, saturated liquid density, saturated vapor density, and vapor pressure of pure components are accurately reproduced compared with experimental values. Furthermore, the predicted properties including derivatives of alpha function, such as enthalpy of vaporization, entropy of vaporization and isobaric heat capacity of liquid, also have decent accuracy. The global average absolute relative deviation (AAD) of saturated liquid density, saturated vapor density, saturated vapor pressure, enthalpy of vaporization, entropy of vaporization, and isobaric heat capacity of liquid in a wide reduced temperature (Tr) range of subcritical region reproduced by this work are 4.33%, 4.18%, 3.19%, 2.26%, 2.27%, and 5.82%, respectively. Substantial improvement has been achieved for the isobaric liquid heat capacity calculation.</p>

Sign in / Sign up

Export Citation Format

Share Document