An Empirical Correlation Relating Equilibrium Compressibility Factors for Pure Substances

2019 ◽  
Vol 40 (10) ◽  
Author(s):  
Bahador Abolpour ◽  
Mostafa Rahmanzadeh
Keyword(s):  
Empirical Correlation ◽  
Pure Substances ◽  
Compressibility Factors

EQUATIONS OF STATE FOR FLUIDS: THE LIQUID-VAPOR EQUILIBRIUM (LVE)

2008 ◽  
Vol 22 (30) ◽  
pp. 5335-5347 ◽  
Author(s):  
JIANXIANG TIAN ◽  
YUANXING GUI
Keyword(s):  
Experimental Data ◽  
Equations Of State ◽  
Packing Fraction ◽  
Optimal Choice ◽  
Critical Conditions ◽  
Mechanics Model ◽  
Vapor Equilibrium ◽  
Pure Substances ◽  
Compressibility Factors ◽  
Liquid Vapor

Historically, the development of equations of state for fluids has almost invariably followed the lead of the van der Waals (vdW) equation which includes an attraction term and a repulsion term. In this paper, using a simple statistical mechanics model, we introduce a parameter σ as both the power and a coefficient of the packing fraction y which locates at the numerator of the vdW attraction term. Then nine equations of state are constructed to solve the critical conditions and the main thermodynamic properties of pure substances at liquid-vapor equilibrium. As a result, the correct critical compressibility factors of Nitrogen, Argon, Carbon dioxide, Ethene, Methane, Oxygen, Propene, Water and Hydrogen, are obtained with an optimal choice of parameter σ. Good predictions of these equations to the liquid-vapor equilibrium properties below critical temperature are reported and compared with experimental data.

Equation of state of a Lennard-Jones 12-6 pairwise additive fluid

1980 ◽  
Vol 45 (4) ◽  
pp. 977-983 ◽  
Author(s):  
Jan Sýs ◽  
Anatol Malijevský
Keyword(s):  
Equation Of State ◽  
Empirical Equation ◽  
The State ◽  
Critical Properties ◽  
Lennard Jones ◽  
State Behaviour ◽  
Compressibility Factors

An empirical equation of state was proposed, which is based on pseudoexperimental data on the state behaviour. The equation can be used at reduced temperatures from the range 0.7-100.0 and reduced densities up to 2. Calculated compressibility factors and critical properties agree well with available literature data.

A Modified Semi-Empirical Correlation for Designing Two-Phase Separators

2021 ◽  
pp. 108782
Author(s):  
Mehdi Fadaei ◽  
M.J. Ameri ◽  
Y. Rafiei ◽  
Kayvan Ghorbanpour
Keyword(s):  
Empirical Correlation ◽  
Two Phase ◽  
Semi Empirical

scholarly journals Kinetic and Microhydrodynamic Modeling of Fenofibrate Nanosuspension Production in a Wet Stirred Media Mill

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1055
Author(s):  
Gulenay Guner ◽  
Dogacan Yilmaz ◽  
Ecevit Bilgili
Keyword(s):  
Rate Constant ◽  
Kinetic Models ◽  
Multiple Linear Regression Model ◽  
Empirical Correlation ◽  
P Value ◽  
Order Kinetic ◽  
Stirrer Speed ◽  
Predictive Capability ◽  
Breakage Rate ◽  
The Impact

This study examined the impact of stirrer speed and bead material loading on fenofibrate particle breakage during wet stirred media milling (WSMM) via three kinetic models and a microhydrodynamic model. Evolution of median particle size was tracked via laser diffraction during WSMM operating at 3000–4000 rpm with 35–50% (v/v) concentration of polystyrene or zirconia beads. Additional experiments were performed at the center points of the above conditions, as well as outside the range of these conditions, in order to test the predictive capability of the models. First-order, nth-order, and warped-time kinetic models were fitted to the data. Main effects plots helped to visualize the influence of the milling variables on the breakage kinetics and microhydrodynamic parameters. A subset selection algorithm was used along with a multiple linear regression model (MLRM) to delineate how the breakage rate constant k was affected by the microhydrodynamic parameters. As a comparison, a purely empirical correlation for k was also developed in terms of the process/bead parameters. The nth-order model was found to be the best model to describe the temporal evolution; nearly second-order kinetics (n ≅ 2) was observed. When the process was operated at a higher stirrer speed and/or higher loading with zirconia beads as opposed to polystyrene beads, the breakage occurred faster. A statistically significant (p-value ≤ 0.01) MLRM of three microhydrodynamic parameters explained the variation in the breakage rate constant best (R2 ≥ 0.99). Not only do the models and the nth-order kinetic–microhydrodynamic correlation enable deeper process understanding toward developing a WSMM process with reduced cycle time, but they also provide good predictive capability, while outperforming the purely empirical correlation.

Correlation of Melting Results for Both Pure Substances and Impure Substances

1986 ◽  
Vol 108 (3) ◽  
pp. 649-653 ◽  
Author(s):  
E. M. Sparrow ◽  
G. A. Gurtcheff ◽  
T. A. Myrum
Keyword(s):  
Solid Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Vertical Tube ◽  
Step Change ◽  
Pure Substance ◽  
Characteristic Temperatures ◽  
Pure Substances ◽  
T Values ◽  
Melting Experiments

Melting experiments were performed encompassing both pure and impure substances. The pure substances included n-octadecane paraffin and n-eicosane paraffin, while the impure substances were mixtures synthesized from the pure paraffins. The experiments were carried out in a closed vertical tube whose wall was subjected to a step-change increase in temperature to initiate the melting. For each impure substance, supplementary measurements were made of two characteristic temperatures: the temperature T** at which melting of the solid phase first begins and the lowest temperature T* at which the melting can go to completion. For a pure substance, T** = T*. The time-dependent melting results for all the investigated substances, both pure and impure, were well correlated as a function of FoSte**(Gr**)1/8 alone, where the ** signifies the presence of T** in the temperature difference which appears in Ste and Gr. This correlation enables melting rates for impure substances to be determined from melting rates for pure substances. The T** values needed for the implementation of the correlation can be obtained from simple experiments, obviating the need for the complete equilibrium phase diagram.

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