scholarly journals Behavior of a Binary Asymmetric Mixture of Interacting Particles in the Supercritical Region

2020 ◽  
Vol 65 (9) ◽  
pp. 768
Author(s):  
M. P. Kozlovskii ◽  
O. A. Dobush
Keyword(s):  
Binary Mixture ◽  
Zero Mode ◽  
Equations Of State ◽  
Interacting Particles ◽  
Interaction Potentials ◽  
Separate Species ◽  
Relative Temperature ◽  
Widom Line ◽  
Mixing Parameter ◽  
Line Of Critical Points

We propose a method for describing the phase behavior of a system consisting of particles of two sorts. The interaction of each species is described by interaction potentials containing the repulsive and attractive components. Asymmetry is ensured by different values of the interaction potentials of each sort. The grand partition function of a binary mixture is calculated in the zero-mode approximation. A line of critical points, which correspond to different proportions of the components, is calculated for specific values of parameters of the interaction potential. We have obtained an equation that relates the introduced mixing parameter x to the concentration of the system. An explicit expression of the pressure of the binary mixture is derived as a function of the relative temperature and the mixing parameter x to plot the Widom line. It is established that, for boundary values of this parameter (x = 0 and x = 1), the equation of state of a mixture turns into equations of state of its separate species.

Applications of the Soave-Redlich-Kwong Equations of State Using Matlab

2011 ◽  
Vol 225-226 ◽  
pp. 492-495
Author(s):  
Lan Yi Sun ◽  
Cheng Zhai ◽  
Hui Zhang
Keyword(s):  
High Pressure ◽  
Binary Mixture ◽  
Chemical Equilibrium ◽  
Equations Of State ◽  
Ammonia Synthesis ◽  
Pure Component ◽  
Synthesis Reaction ◽  
Liquid Equilibrium ◽  
Vapor Liquid Equilibrium ◽  
Vapor Liquid

In this paper, using Matlab to solve Soave-Redlich-Kwong (SRK) EOS, as well as the estimation of pure component properties, plotting of vapor-liquid equilibrium (VLE) diagram and calculation of chemical equilibrium, is presented. First the SRK EOS is used to predict several pure-component properties, such as liquid and gas molar volumes for isobutane. The vapor-liquid isobaric diagram is then plotted for a binary mixture composed of n-pentane and n-hexane under the pressures of 1.5*10^5 and 7*10^5 Pa respectively. Finally, the extent of ammonia synthesis reaction under high pressure is calculated.

On the Concentration Fluctuations of a Binary Mixture of Hard Spheres

1988 ◽  
Vol 43 (10) ◽  
pp. 847-850 ◽  
Author(s):  
L. J. Gallego ◽  
J. A. Somoza ◽  
M. C. Blanco
Keyword(s):  
Phase Transition ◽  
Binary Mixture ◽  
Hard Sphere ◽  
Equations Of State ◽  
Hard Spheres ◽  
Fluid Phase ◽  
Packing Fraction ◽  
Concentration Fluctuations ◽  
Entropy Of Mixing ◽  
First Approximation

Abstract We have computed the concentration fluctuations, Scc(0), in a binary mixture of hard spheres on the basis of the Percus-Yevick compressibility (PYC), Percus-Yevick virial (PYV) and Mansoori- Carnahan-Starling (MCS) equations of state. We have also used the Flory-Huggins (FH) model for an athermal solution as a first approximation to the hard sphere description. At fluid packing fraction values, the PYC and MCS theories give similar Scc (0) results, whereas the differences between these and those derived from the PYV equation are more significant. The FH model appears to give rather bad results, which is consistent with the studies of other authors on the entropy of mixing of a binary mixture of hard spheres. The impossibility of a fluid-fluid phase transition in this kind of system is clearly shown by the behaviour of Scc (0) in any of the theories studied.

Supercritical Pseudo Boiling in Cubic Equations of State

2021 ◽  
Author(s):  
Daniel T. Banuti
Keyword(s):  
Temperature Interval ◽  
Reference Data ◽  
Equations Of State ◽  
Acentric Factor ◽  
Widom Line ◽  
Dominant Feature ◽  
Coexistence Line ◽  
Liquid States ◽  
Advanced Cycles ◽  
Low Pressures

Abstract Today, modern combustion systems and advanced cycles often reach operating pressures exceeding the working fluid’s or fuel’s critical pressure. While the liquid-gas coexistence line is the dominant feature in the fluid state space at low pressures, a supercritical analog to boiling, pseudo boiling, exists at supercritical pressures. Pseudo boiling is the transcritical state transition between supercritical liquid states and supercritical gaseous states, associated with peaks in heat capacity and thermal expansion. This transition occurs across a finite temperature interval. So far, the relation between the pseudo boiling line of tabulated hi-fi p-v-T data and the behavior of efficient engineering cubic equations of state (EOS) is unclear. In the present paper, we calculate the slope of the pseudo boiling line analytically from cubic equations of state. The Redlich-Kwong EOS leads to a constant value for all species, Peng-Robinson and Soave-Redlich-Kwong EOS yield a cubic dependency of the slope on the acentric factor. For more than twenty compounds with acentric factors ranging from −0.38 to 0.57 calculated slopes are compared with NIST data and vapor pressure correlations. Particularly the Peng-Robinson EOS matches reference data very well. Classical empirical values of Guggenheim or Plank & Riedel are obtained analytically. Then, pseudo boiling predictions of the Peng Robinson EOS are compared to NIST data. Deviations in transition temperature interval, and nondimensional parameters of the distributed latent heat are compared. Especially the different caloric behavior of tabulated fluid data for H2, N2, CO2, and H2O cannot be reproduced by the Peng Robinson EOS. These results may open the way towards new EOS with specific emphasis on Widom line and supercritical transition behavior.

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