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**Search for:**linear-isotherm-regularities

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#### Deriving analytical expressions for the ideal curves and using the curves to obtain the temperature dependence of equation-of-state parameters

, Article International Journal of Thermophysics ; Volume 27, Issue 5 , 2006 , Pages 1564-1589 ; 0195928X (ISSN) ; Izanloo, C ; Sharif University of Technology
2006

Abstract

Different equations of state (EOSs) have been used to obtain analytical expressions for the ideal curves, namely, the Joule-Thomson inversion curve (JTIC), Boyle curve (BC), and Joule inversion curve (JIC). The selected EOSs are the Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), Deiters, linear isotherm regularity (LIR), modified LIR (MLIR), dense system equation of state (DSEOS), and van der Waals (vdW). Analytical expressions have been obtained for the JTIC and BC only by using the LIR, MLIR, and vdW equations of state. The expression obtained using the LIR is the simplest. The experimental data for the JTIC and the calculated points from the empirical EOSs for the BC are well fitted into...

#### Density and temperature dependencies of liquid surface tension

, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 2 , 2011 , Pages 79-90 ; 10219986 (ISSN) ; Parsafar, G. A ; Akbarzadeh, H ; Sharif University of Technology
2011

Abstract

In this paper the density and temperature dependencies of surface tension are investigated. Using the Lennard-Jones (12,6), as an effective pair interaction potential, a linear expression is derived for isotherms of γ /ρ 2 versus ρ 2 for some normal and ChloroFluoroCarbons (CFCs) fluids, where is surface tension and ρ = 1/v is molar density. The linearity behavior of the derived equation is well fitted onto the experimental data of surface tension for monatomic, diatomic, nonpolar, polar, hydrogen-bonded and chlorofluorocarbons. In addition, the temperature dependence of surface tension for 20 different fluids is examined, in which the contributions of both terms of the average effective...

#### Analysis of different EOSs in predicting the ideal curve and deriving the temperature dependencies of their parameters

, Article International Journal of Thermophysics ; Volume 25, Issue 6 , 2004 , Pages 1819-1834 ; 0195928X (ISSN) ; Saydi, H ; Sharif University of Technology
2004

Abstract

Regularities shown by different fluids along the contour of the ideal compressibility factor Z= PV/(RT)=1 in the temperature density plane was used to test the accuracy of the equations of state and derive temperature dependencies of their parameters. The contour, also known as the Zeno line, was empirically observed to be nearly linear. The precision of the van der Waals equation in predicting the Zeno line was evaluated. It was shown that the equation could predict a linear relation between temperature and density on the Z=1 contour, qualitatively

#### Calculation of Transport Properties of Dense Fluids Using Modified Enskog Theory (MET) and Appropriate Equation of State (EoS)

, M.Sc. Thesis Sharif University of Technology ; Parsafar, Gholam Abbas (Supervisor)
Abstract

In this research, a method based on the modified Enskog theory (MET) and some equations of state has been used to calculate the transport properties of some dense fluids. The main limitation to using the MET is the lack of experimental data for the co-volume, b0, that are substituted from the hard sphere (HS) theory, and the zero density transport properties that are substituted from the kinetic theory of gases for the HS in the MET expression, because of the fact that dense fluids behave more and less like a HS fluid. So a quadratic expression for both ηY/(√T ρ) and λY/(ρ√T) (C_(V,m)+ (9/4)R) in terms of Y at high densities (ρ > ρc) for each isotherm is expected, where Y = (T (∂p/∂T))/ρRT...

#### Investigation the Dependency of Surface Tension to Density and Temperature at Dense Systems

, M.Sc. Thesis Sharif University of Technology ; Parsafar, Gholamabbas (Supervisor)
Abstract

In this thesis heat transfer coefficient and temperature distribution of two Non-Newtonian and a Newtonian fluids in stirred vessel are investigated using Computational Fluid Dynamic (CFD). This vessel is agitated with new impeller called MAXBLEND. Non-Newtonian fluids are aqueous solutions of carboxymethyl cellulose 1.5%w/w and xanthan gum 3% w/w and Newtonian fluid is glycerin. This vessel is simulated in laminar regime with Reynolds number less than 14. The results of simulation are compared with correlation proposed by Kawase et al.

Furthermore as a new research for this impeller, the effects of vessel diameter and position of impeller in the vessel on heat transfer coefficient are...

Furthermore as a new research for this impeller, the effects of vessel diameter and position of impeller in the vessel on heat transfer coefficient are...

#### Deriving linear isotherms for solids

, Article Fluid Phase Equilibria ; Volume 271, Issue 1-2 , 2008 , Pages 94-102 ; 03783812 (ISSN) ; Parsafar, G. A ; Dinpajooh, M ; Sharif University of Technology
2008

Abstract

In this paper, we have derived two equations of state, one for the metallic and ionic solids and the other for the remaining solids on the basis of the concept of the average effective pair potential (AEPP). According to the former EOS, (Z-1)υ2 is linear with respect to 1/ρ, where Z is the compressibility factor and υ = 1/ρ is the molar volume for each isotherm. On the basis of the latter EOS, (Z-1)υ2 is a linear function in terms of ρ2 for each isotherm. As these EOSs suggest, the temperature dependencies of the internal energy is separable from its density dependencies. Hence, the heat capacity of a solid is independent of its density, interaction potential parameters and non-ideal thermal...

#### Extension of linear isotherm regularity to long chain primary, secondary and tertiary alcohols, ketones and 1-carboxylic acids by group contribution method

, Article Fluid Phase Equilibria ; Volume 234, Issue 1-2 , 2005 , Pages 11-21 ; 03783812 (ISSN) ; Kalantar, Z ; Sharif University of Technology
2005

Abstract

In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,...

#### Calculation of the transport properties of dense fluids using modified Enskog theory and an appropriate equation of state

, Article Fluid Phase Equilibria ; Volume 253, Issue 2 , 2007 , Pages 108-117 ; 03783812 (ISSN) ; Kalantar, Z ; Sharif University of Technology
2007

Abstract

In this work, a new method based on the modified Enskog theory (MET) is presented for calculation of transport properties at high densities (ρ > ρc). The main limitation of using the MET is lack of experimental data for co-volume, b0. We have substituted b0 from hard sphere (HS) theory and zero density transport properties from the kinetic theory of gases for HS in the MET expression, because of the fact that dense fluids behave more and less like a HS fluid. As a result, a simple linear expression for the self diffusion (D) and quadratic expressions for viscosity (η) and thermal conductivity (λ) coefficients have been obtained in terms of Y at high densities (ρ > ρc), where Y = (T (∂ p / ∂...

#### Influence of quantum effect on deviation from linear isotherm regularity

, Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 555-560 ; 10263098 (ISSN) ; Parsafar, G. A ; Sharif University of Technology
2012

Abstract

A general regularity was found based on an effective pair potential of Lennard-Jones LJ (12, 6), for both dense, nonmetallic and nonionic fluids and solids according to which (Z-1) v2 linearly varies with respect to ρ2 for each isotherm, and this equation of state (EoS I) is known as LIR. However, despite the fact that Ne is a simple spherical species, unexpectedly, its solid and liquid phases both show a significant deviation from EoS I. In this work, we have investigated the accuracy of the EoS I for other systems, including quantum light molecules, such as D 2, H 2 and He, in both fluid and solid states at different temperatures. Like Ne, we have noticed that these systems do not well...

#### Using molecular dynamic simulation data of calcite in a wide pressure range to calculate some of its thermodynamic properties via some universal equations of state

, Article Molecular Physics ; Volume 106, Issue 21-23 , 2008 , Pages 2545-2556 ; 00268976 (ISSN) ; Shokouhi, M ; Parsafar, G. A ; Sharif University of Technology
2008

Abstract

Molecular dynamics, MD, simulation of calcite (CaCO3) is selected to compare the p-v-T behaviour of some universal equations of state, UEOS, for the temperature range 100 K ≤ T 800 ≤ K, and pressures up to 3000 kbar. The isothermal sets of p-v-T data generated by simulation were each fitted onto some three- and two-parameter EOSs including Parsafar and Mason (PM), Linear Isotherm Regularity (LIR), Birch-Murnaghan (BM), Shanker, Vinet, Baonza and Modified generalized Lennard-Jones (MGLJ) EOSs. It is found that the MD data satisfactorily fit these UEOS with reasonable precision. Some features for a good UEOS criteria such as temperature dependencies of coefficients, pressure deviation,...