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A method for predicting the phase behavior of petroleum fractions using equations of state is proposed. The procedure is tested on binary mixtures and on real petroleum fractions. The experimental data used for the comparison are Henry's constants as determined by GLC measurements. The performances of cubic and non cubic equations of state in predicting multicomponent data are compared. The equation of state based on the Perturbed Hard Chain Theory gives excellent results in the predictions of Henry's constants of light gases in petroleum fractions.

One of the limitations of any group contribution method developed so far is the impossibility to distinguish among different isomers. This paper suggests a very simple procedure to extend the solution of group theory to mixtures containing isomers. The procedure suggested is based on theoretical considerations and is derived from phase equilibrium data for mixture of isomers in the dilute regions. A linear correlation is found between the surface area fraction (q) of the molecules and the ratio of the critical pressure over the critical temperature. Furthermore the investigation shows that the q values of the organic compounds which exhibit strong association phenomena should be substantially reduced: numerical values are reported depending upon the availability of experimental data.

This work proposes a method for the determination of data at infinite dilution and at very low concentration based on the isothermal measurement of the difference in pressure between two static cells containing the pure component and the mixture respectively. The method is particularly suitable for investigating binary systems whose components differ strongly in volatility, and when other methods such as gas liquid chromathography or ebulliometry fail.

This work presents a multi-scale approach to reacting and expanding polyurethane (PU) foams modeling and simulation. The modeling strategy relies on two pillars: an atomistic model (molecular dynamics (MD)/Grand Canonical Monte Carlo (GCMC)) that provides liquid mixture density and reactant solubility and a continuum model (CFD) in which the expansion characteristics of the foam is modeled exploiting the results of the atomistic simulations. The resulting coupled model is validated for two different PU systems applied in four batches with chemical and physical blowing agents. The results demonstrate the efficacy and reliability of the developed model in the simulation of different PU foam properties such as apparent density and temperature evolutions.

Biology is dominated by polyanions (cell membranes, nucleic acids, and polysaccharides just to name a few), and achieving selective recognition between biological polyanions and synthetic systems currently constitutes a major challenge in many biomedical applications, nanovectors-assisted gene delivery being a prime example. This review work summarizes some of our recent efforts in this field; in particular, by using a combined experimental/computation approach, we investigated in detail some critical aspects in self-assembled nanomicelles and two major polyanions—DNA and heparin.

Bovine viral diarrhea virus (BVDV) infection is still a plague that causes important livestock pandemics. Despite the availability of vaccines against BVDV, and the implementation of massive eradication or control programs, this virus still constitutes a serious agronomic burden. Therefore, the alternative approach to combat Pestivirus infections, based on the development of antiviral agents that specifically inhibit the replication of these viruses, is of preeminent actuality and importance. Capitalizing from a long-standing experience in antiviral drug design and development, in this work we present and characterize a series of small molecules based on the 9-aminoacridine scaffold that exhibit potent anti-BVDV activity coupled with low cytotoxicity. The relevant viral protein target – the RNA-dependent RNA polymerase – the binding mode, and the mechanism of action of these new antivirals have been determined by a combination of in vitro (i.e., enzymatic inhibition, isothermal titration calorimetry and site-directed mutagenesis assays) and computational experiments. The overall results obtained confirm that these acridine-based derivatives are promising compounds in the treatment of BVDV infections and, based on the reported structure-activity relationship, can be selected as a starting point for the design of a new generation of improved, safe and selective anti-BVDV agents.

In this paper we report the synthesis, in vitro anticancer activity, and the experimental/computational characterization of mechanism of action of a new series of E isomers of triazolo[4,5- b / c ]pyridin-acrylonitrile derivatives ( 6c-g , 7d-e , 8d-e , 9c-f , 10d-e , 11d-e ). All new compounds are endowed with moderate to interesting antiproliferative activity against 9 different cancer cell lines derived from solid and hematological human tumors. Fluorescence-based assays prove that these molecules interfere with tubulin polymerization. Furthermore, isothermal titration calorimetry (ITC) provides full tubulin/compound binding thermodynamics, thereby ultimately qualifying and quantifying the interactions of these molecular series with the target protein. Lastly, the analysis based on the tight coupling of in vitro and in silico modeling of the interactions between tubulin and the title compounds allows to propose a molecular rationale for their biological activity.

Desmoid‐type fibromatosis (DF) is a rare mesenchymal lesion with high risk of local recurrence. Specific β‐catenin mutations (S45F) appeared to be related to this higher risk compared to T41A‐mutated or wild‐type (WT). We explored the influence of both mutations and WT on structure stability and affinity of β‐catenin for α‐catenin and the pattern of gene expression that may influence DF behavior. Using 33 surgically resected primary DFs harboring T41A (n = 14), S45F (n = 10), or WT (n = 9), we performed a comparative molecular analysis by protein/protein interaction modeling, gene expression by DASL microarrays, human inflammation gene panel, and assessment of immune system‐based biomarkers by immunohistochemistry. Mutated proteins were more stable than WT and formed a weaker complex with α‐catenin. Consensus unsupervised gene clustering revealed the presence of two DF group‐mutated (T41A + S45F) and WT (P = 0.0047). The gene sets ‘Inflammatory‐Defense‐Humoral Immune Response’ and ‘Antigen Binding’ were significantly enriched in T41A. The deregulation of 16 inflammation‐related genes was confirmed. Low numbers of T cells and tumor‐associated macrophages (TAM) infiltrating the tumors and low/absent PD‐1/PD‐L1 expression were also identified. We demonstrated that mutated DFs (T41A or S45F) and WT are two distinct molecular subgroups with regard to β‐catenin stability, α‐catenin affinity, and gene expression profiling. A different inflammation signature characterized the two mutated groups, suggesting mediation either by T41A or by S45F. Finally, all mutated cases showed a low number of TIL and TAM cells and a low or absent expression of PD‐1 and PD‐L1 consistent with β‐catenin activation insensitive to checkpoint blockade.

Generation 2 cationic carbosilane dendrimers hold great promise as internalizing agents for gene therapy as they present low toxicity and retain and internalize the genetic material as an oligonucleotide or siRNA. In this work we carried out complete in silico structural and energetical characterization of the interactions of a set of G2 carbosilane dendrimers, showing different affinity towards two single strand oligonucleotide (ODN) sequences in vitro. Our simulations predict that these four dendrimers and the relevant ODN complexes are characterized by similar size and shape, and that the molecule-specific ODN binding ability can be rationalized only by considering a critical molecular design parameter: the normalized effective binding energy ΔG(bind,eff)/N(eff), i.e. the performance of each active individual dendrimer branch directly involved in a binding interaction.

2-Oxoglutaric acid (2-OG) has gained considerable attention because of its newly discovered signalling role in addition to its established metabolic functions. With the aim of further exploring the signalling function of 2-OG, here we present a structure-activity relationship study using 2-OG probes bearing different carbon chain lengths and terminal groups. Our results highlight the importance of the five-membered carbon molecular skeleton and of the two carboxylic terminals in maintaining the signalling functions of the parent molecule 2-OG. These findings provide valuable information for designing new, effective molecular probes able to dissect and discriminate the newly discovered, complex signalling role of 2-OG from its canonical activity in metabolism.

Many enzymatic reactions are near-equilibrium reactions. This often limits final yield and hence application of biocatalyzed processes in the industrial production. The most widely applied strategy to overcome this issue is solvent selection. It must be underlined that measuring the equilibrium position experimentally is a difficult and time-consuming procedure and any tool for predicting the solvent effect on the reaction equilibrium can be very valuable. The present work reports on the development of BESSICC, an algorithm to calculate the effect of medium composition on biocatalyzed reactions equilibrium. It is based on COSMO-RS calculation of activity coefficients of all the species in the reaction mixture and minimization of Gibbs free energy of the reaction. Starting from one single experimental measurement of the equilibrium position for a given biocatalyzed reaction it can predict the yield of the reaction in any other solvent or solvent mixture. Predictions are accurate, the errors of prediction are in average below 25% for the esterification of dodecanoic acid with menthol and below 65% for esterification of 1-dodecanoic acid with 1-dodecanol. The best predictions show an error well below 5%.

Pure component vapour pressures for N-methylmorpholine and vapour-liquid equilibrium (VLE) data for the binary systems N-methylmorpholine/water and N-methylmorpholine/morpholine are measured. Starting from experimental binary data and literature data, the prediction of the VLE behaviour of N-methylmorpholine/morpholine/water system and the simulation of the recovery of the N-methylmorpholine by distillation was performed

A perturbed hard chain theory based equation of state is investigated in view of its application to supercritical fluid extraction process calculations. This investigation is an extension of a previous paper in which attention was given to pure component properties and in which a method was proposed for estimating the pure component parameters from the molecular structure. Binary systems of supercritical fluids and nonpolar molecules are considered in this paper. A method is proposed for estimating a priori the binary interaction parameter from molecular structure information. A universal set of parameters is found for hydrocarbon—supercritical fluid mixtures depending only upon the supercritical fluid and the hydrocarbon family. The results obtained are fairly good and comparable with other predictive equations of state available in the literature. The advantages of using this method is its integration with the pure component parameter estimation method proposed in a previous paper. Good results were also obtained in the prediction of the volumetric properties of the liquid and the vapor phase.

In this preliminary study we report the antiviral screening of triazolo[4,5-g]quinoline derivatives (compounds 1–6). 4,9-Dihydrotriazolo[4,5-g]quinoline-1-oxide (1) stood out as a new, small molecule endowed with a selective, promising activity in cell-based assays against HIV-1wt and clinically relevant NNRTI resistant mutants. In order to identify the molecular target, compound 1 was assayed in enzyme assay against the HIV-1wt RT. The molecular modeling strategy adopted yielded a rationale, in terms of molecular interactions and free energy of binding, for the possible reasons of the activity of this compound against NNRTI-resistant HIV-1 mutants with the RT isoforms K103N and Y181C.

3H-1,3,4-Oxadiazol-2-one derivatives were synthesized and tested for their in vitro antimycobacterial activity. Oxadiazolone derivatives showed an interesting antimycobacterial activity against the reference strain of Mycobacterium tuberculosis H(37)Rv. Molecular modeling investigations were performed and showed that the active compounds possess all necessary features to target the protein active site of the mycobacterial cytochrome P450-dependent sterol 14alpha-demethylase in the sterol biosynthesis pathway as the calculated free energy of binding were in agreement with the corresponding MIC values.

A method is proposed for the calculation of solubilities in compressed carbon dioxide. The method is illustrated with the hard-sphere equation of state, but the main feature is the use of low-pressure—low-temperature solubility data for determining the binary interaction parameters. Examples are reported for carbon dioxide because of its industrial use in supercritical fluid extraction.

A hierarchical procedure bridging the gap between atomistic and mesoscopic simulation for polymer-clay nanocomposite (PCN) design is presented. The dissipative particle dynamics (DPD) is adopted as the mesoscopic simulation technique, and the interaction parameters of the mesoscopic model are estimated by mapping the corresponding energy values obtained from atomistic molecular dynamics (MD) simulations. The predicted structure of the nylon 6 PCN system considered is in excellent agreement with previous experimental and atomistic simulation results.

Isothermal-isobaric (NPT) molecular dynamics simulations have been performed to investigate the structure, morphology, and energetics of polymer organoclay nanocomposites based on seven nonsteroidal anti-inflammatory drugs (NSAIDs), two biocompatible polymers, and hydrotalcite as the clay mineral, both in an anhydrous and in a solvated environment. The results of our theoretical computations show that nanoconfined conformations of smaller NSAIDs are more affected by the presence of water molecules in the clay gallery with respect to their larger counterparts. Moreover, the presence of water in the mineral interlayer space decreases the interaction energy between the NSAID molecules and the clay, and this detrimental effect is further enhanced by the presence of polar moieties onto the NSAIDs. Finally, from the thermodynamics standpoint, the best intercalation results in a solvated environment could be obtained with PVA in the case of less polar drugs, while PHB could be the polymer of choice in the case of highly polar NSAIDs.

This paper presents a new approach for predicting solvent effects on esterification reactions of industrial importance in the field of biocatalysis. The COSMO-RS method has been used to calculate the activity coefficients of the chemical species involved in various reactions, carried out in different solvents. For comparison we also used the traditional UNIFAC method. Three lipase-catalyzed esterifications were considered: (1) 1-dodecanoic acid with menthol in n-hexane, n-heptane, cyclohexane, 2,2,4-trimethylpentane, toluene, acetonitrile, and 2-methyl-2-butanol; (2) 1-dodecanoic acid and 1-dodecanol in n-hexane, n-heptane, cyclohexane, 2,2,4-trimethylpentane, and toluene; and (3) glycerol and n-octanoic acid in acetonitrile, benzene, and toluene and in the neat reaction mixture (without any solvent). Predicted activities were used to calculate the thermodynamic equilibrium ratio. This should be independent of medium, and the variation in COSMO-RS values is at most 9-fold (corresponding to a DeltaG degrees of about 5.5 kJ/mol, which would still be a very useful prediction) and often only 2-fold (corresponding to less than 2 kJ/mol or 0.5 kcal/mol, therefore comparable with experimental error). UNIFAC is weaker, especially when important roles are played by conformational freedom, intramolecular interactions, strong polar effects, and charge distribution of molecules in the mixture. The relative percent deviations from the mean of equilibrium constants in different solvents range between 17 and 49 for COSMO-RS versus 32 to 65 for UNIFAC. The COSMO-RS method opens up new perspectives for the development of theoretical models for solvent selection with general applicability.

Diffusion coefficients D of H2, He, O2, N2, and CO2 in different rubbery amorphous polymeric matrices were estimated by atomistic molecular dynamics simulations at 298 K using the Einstein relationship, and compared with the relevant experimental values, where available. The simulated diffusion coefficients D of all the gases in all polymers considered almost regularly decreased with increasing molecular gas volumes and increasing polymer glass transition temperature. Further, solubility coefficients and heats of solution were obtained for all gases from Grand Canonical Monte Carlo simulations, which were also used to calculate sorption isotherms. In general, there is a good agreement between experimental and simulated values of diffusion and solubility coefficients for all gases considered.

Molecular dynamics simulations are used to investigate the rheological behavior of confined linear alkane chains under shear flow conditions. The simulated fluids are contained between atomistic, pure titanium walls, coupled to an external bath to maintain the temperature at a constant value. Shear flow conditions are imparted by moving the metal walls in opposite directions, and the corresponding density, velocity, and temperature profiles of the systems are calculated. For the shear rates investigated, all linear alkane chains exhibit a tendency for slip at the walls, evidenced by density profiles divided into two distinct regions and small discontinuities in the velocity and temperature profiles at the wall/fluid interface. Compared to equilibrium, alkane chains show higher mean-square end-to-end distances, characterized by higher components along the shear flow direction.

This paper presents two alternative procedures based on quantum/conductor-like screening model (COSMO) calculations and on molecular mechanics/dynamics simulations, respectively for estimating the PHSCT equation of state (EOS) parameters and to predict vapor–liquid equilibria (VLE) behavior for pure, alternative refrigerants, as well as for their binary mixtures. The quality of the predictions achieved with both method proposed, in conjunction with the confined computational time aspects involved, can be considered satisfactory, so that these strategies can be judged as promising routes toward an on-line coupling between molecular and process simulation.

The correlating and predictive capabilities of a thermodynamic model based on the perturbation theory are investigated, with reference to mixtures containing components of di!erent size and molecular interactions. The simpli"ed Perturbed-Hard-SphereChain (PHSC) equation of state is applied to a series of pure polymers, a number of solvents and pure carbon dioxide, and both volumetric and equilibrium properties are considered. The ability of the proposed model to reproduce experimental phase equilibrium data is discussed and tested with reference to binary and multicomponent mixtures, in the presence of vapor}liquid, liquid}liquid and vapor}liquid}liquid equilibria. Attention is focused on the ternary system polystyrene}cyclohexane}carbon dioxide, to test the proposed thermodynamic model in view of simulating supercritical antisolvent-induced fractionation processes. It is shown that the PHSC equation of state can be reliably used for calculating the phase behavior of such a complex system in di!erent conditions. ( 2000 Elsevier Science Ltd. All rights reserved.

This work aims at extending the characterization of binary systems containing mixtures of n-C16 with branched saturated hydrocarbons of similar, higher, and lower number of carbon atoms. The systems considered are n-C16 with isooctane (2,2,4-trimethylpentane), cyprane (2,2,4,4,6,8,8-heptamethylnonane), pristane (2,6,10,14-tetramethylpentadecane), and squalane (2,6,10,15,19,23-tetracosane). Density, viscosity, refractive index, molar refractivity, excess volume, viscosity deviation function, and refractivity deviation function at 298.15 K are reported. Measured data are correlated with semiempirical models and parameters are reported.

The evaluation of thermodynamic properties of pure hydrofluorocarbons and hydrocarbons, and their binary mixtures is considered. A modification of the perturbed-hard- sphere-chain equation of state is applied to these compounds and tested on a large database of refrigerants, hydrocarbons and their mixtures, with reference to both volumetric and equilib- rium properties. The ability of the proposed model to reproduce experimental values is discussed. First, the theoretical background of the model is revisited in order to obtain a predictive method for the 'a priori' calculation of the values of parameters which reflect the size, shape and interaction energy of the molecule (three parameters for each pure component). Expressions to predict these values as a function of molecular quantities are presented and it is shown that the proposed model can be reliably used for calculating the properties of pure refrigerants and hydrocarbons, starting from the Bondi volume and surface area values, and the vapor pressure curve (2% error in the PVT behavior at worst). Then, the extension to mixtures is addressed. Attention is focused on the evaluation of binary interaction parameters (k ij ) for systems of refrigerant—refrigerant, hydrocarbon—refrigerant and hydrocarbon—hydrocarbon type. Vapor—liquid equilibrium data of eighteen binary systems at several temperatures have been regressed, with errors in pressure ranging below 2% for refrigerant and below 1% for hydrocarbons when using a single value of k ij for each binary pair, independent of temperature. ( 1998 Elsevier Science Ltd. All rights reserved.

Vapor-liquid (VLE) and liquid-liquid (LLE) equilibria for the toluene + 1,2-propanediol+ water system and the connected binaries have been measured, and the parameters of a thermodynamic model suitable for the description of the system and for the simulation of a multistage separation unit have been derived. The activity coefficients at infinite dilution were determined using GLC, exponential dilutor, and ebulliometry techniques. Comparison was made with previous literature results and from extrapolation of precise VLE results over the composition range determined using a computer-operated differential static apparatus at 303.81 and 343.73 K. In addition, some ternary LLE tie lines at 298.15 K were measured as well as a few ternary vapor-liquid-liquid equilibrium data at other temperatures. Regression analysis of the data was carried out to obtain LJNIQUAC temperature-dependent binary interaction parameters. These parameters were used to model the three-phase distillation column with the help of a commercial process simulator.

Density and kinematic viscosity have been measured with a vibrating tube densimeter and an Ubbelohde capillary viscometer for binary mixtures of 1,1,1-trichloroethane and six paraffins, hexane, heptane, octane, decane, dodecane, and hexadecane, and five cycloparaffinns, cyclohexane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, and butylcyclohexane, at atmospheric pressure and 298.15 K. The dynamic viscosity, excess volume, and viscosity deviation function have been obtained from the density and kinematic viscosity results. The results have been correlated with a polynomial expression for the excess volume and with a recently published model for the mixture viscosity. Parameters for such models are reported

An efficient program for the simulation of a supercritical multistage multicomponent separation column with ideal stages has been developed. Models for calculating phase equilibria and densities are briefly described and applied to the simulation of the process. The algorithm used was a simultaneous convergence Newton method combined with Fibonacci search in order to determine the best damping factor. The use of this method is justified by the description of the nature of the problem. In this work, accurate and rigorous thermodynamic models are combined with robust and reliable simulation algorithms for the description of a supercritical fluid extraction column equipped with a top separator, taking into account enthalpy balances too. In fact, it is important to consider also the occurrence of small temperature changes along the column, because they could give rise to noticeable changes of densities and capacities. The developed program takes advantage of the form of the model equations, utilizing the band structure of the equations and their Jacobian. Computing time was saved by attention to the structure of thermodynamic functions and derivatives.

The goal of this work is to describe the phase behavior of n-paraffins-supercritical fluid binary systems. The n-paraffins are selected in order to be representative of petroleum fractions. Calculations in the full concentration range and in the vicinity of the mixture critical point, are reported for selected binary systems, for which experimental behavior is known from literature. The calculations are performed by means of the perturbed hard chain and cubic equations-of-state. Pure component parameters of the equations are calculated either from pure component properties or via generalized correlations as a function of a characteristic parameter. The effect of binary interaction parameters and of pure component parameters on mixture properties prediction is also checked.

The Sander model for correlation and prediction of salt effects on vapor—liquid equilibria (VLE) of mixed solvents combines a term of the Debye—Huckel type with a modified UNIQUAC equation with concentration dependent parameters. In this work the UNIQUAC equation has been substituted by the original UNIFAC group-contribution model with concentration independent group interaction para-meters. Group interaction parameters have been estimated between ions (Li+, Na+, K+, Ca2+, Ba2+, Sr2+, Cu2+, Ni2+, Hg2+, F−, Cl−, Br−, J−, NO3− and CH3COO−), and solvent groups (CH2, OH, CH3OH, H2O, CH3CO), while previously published group interaction parameters between solvent groups have been maintained. It is shwon that the proposed model represents VLE for solvent—water—salt mixtures with an expected average accuracy of the total pressure around 9% and of the vapor-phase mole fractions around 4%. Since it is a predictive group-contribution method it has a much broader range of applicability than the Sander model.

A perturbed hard chain theory based equation of state is investigated in view of its application to supercritical fluid extraction process calculations. The investigation is focused on pure component properties, since it is essential for any equation to give a good description of volumetric and equilibrium properties of pure compounds before extending it to mixtures. The equation gives good results as far as the correlation of polar and non-polar fluids is concerned. Generalized correlations of the equation parameters are established in terms of Bondi's volume. Their applicability is evaluated on components not included in the data base for the parameter estimation. The results obtained are fairly good, showing that the generalized correlations are convenient specifically for those compounds for which experimental data are difficult to measure. A procedure is proposed to reduce the equation to a one-parameter equation without losing accurary. The single parameter is calculated from vapor pressure datum.

The results of an experimental investigation of five binary mixtures of morpholine with water and alcohols are reported. Data from volumetric measurements ( T and x ) are used to compute excess volumes ( V E ) and partial molar volumes at infinite dilution. The V E data are correlated with Redlich-Kister polynomials.

Results of experimental investigation on the binary mixtures morpholine / methanol (at 74.2 and 30.1 kPa) and morpholine / 2-propanol (at 70.0 and 30.0 kPa) are reported: P, T, x, y data are checked for consistency and then used to calculate parameters of excess Gibbs energy (GE) models.

A procedure is proposed for the accurate estimation of the compositions of vapour and liquid phases in an equilibrium cell from a knowledge of the weight and composition of the feed and the volume of the vapour phase. A cubic equation of state (van der Waals or Redlich-Kwong), modified according to Peneloux, is applied. The pure component parameters are determined from vapour pressure and liquid density values. A single binary constant is determined by imposing the value of the vapour phase volume within the cell. The accuracy of the calculated phase compositions is higher than or comparable to the values obtained by chromatographic analysis, with the advantage of a smaller experimental effort.

A modified version of the chemical-reticular group contribution model CRG is proposed for improving predictions on alkanol-alkane systems containing long-chain molecules. The model gives accurate prediction of VLE and activity coefficients at infinite dilution.

Excess volumes and kinematic viscosities have been measured by means of a vibrating tube densimeter and an Ubbelohde viscometer for 12 binary systems containing 4-methyl-2-pentanone (MIBK). Excess volumes have been correlated by means of a polynomial expression, viscosities by means of the Mc Allister equation

The paper deals with the possibility of predicting phase behavior of oil solutions in light hydrocarbon solvents. Such mixtures contain very many components: one or two well defined light alkanes (solvents) and one poorly defined continuous oil. Having significantly different molecular size, they can exhibit very non ideal phase behavior. We consider a heavy end (residue) which is similar to the feed for deasphalting processes. The fraction is characterized on the basis of Henry's constant data measured by gas liquid chromatography of light hydrocarbons in the heavy end. The heavy end is represented using pseudo-components. The Henry's constant gives all the information relative to the interactions between the light hydrocarbons (solvent) and the model components of the heavy oil. The procedure is tested on gas solubility data at low and high pressure. The perturbed hard chain equation (PHCT) coupled with flash algorithm is used for the calculations. As a result the mixtures considered are described by the thermodynamic model chosen through the pseudo-components used, thus allowing the optimization of deasphalting and solvent recovery processes.

The capability of existing models in extrapolating from infinite dilution properties to region far from the infinite dilution is investigated. Excess Gibbs energy models, group contribution models and equations of state are used for the prediction of the behavior of azeotropic and partially miscible systems. Only experimental infinite dilution activity coefficients are used to obtain parameters for the different models. The results obtained by all the models investigated are compared.

Equations of state of different families are shortly described and reviewed. Simple models, such as the cubic equations of state, are considered in their performance to more sophisticated ones. Furthermore, different mixing rules are discussed, including the simple, random, and the complicate density-dependent mixing rules. Attention has been focused on the problem of the parameter estimation in equations of state: calculations are presented showing how an equation of state can be tuned for representing thermodynamic properties. Limitations of multiproperty and mixture prediction are also put forward.

The performance of differential static apparatus in determining data in dilute regions is studied. The investigation shows that the method is not applicable to low solute activity. It is shown that this limitation is based on theoretical considerations rather than on practical experimental difficulties.

The suitability of existing equations of state for the prediction of heat of mixing data is investigated.

A modification of the perturbed-hard-sphere-chain equation of state (EOS) is used to describe vapor–liquid (VLE) and liquid–liquid equilibria (LLE) of mixtures containing new-generation refrigerants and a lubricant oil. For refrigerants, pure-component parameters are obtained from thermodynamic data. For the oil, they are predicted by a group-contribution method, and the calculation is checked on liquid density values of polyol-ester lubricants. Extension to mixtures is performed by using conventional one-fluid mixing rules with binary interaction parameters regressed from VLE experimental data. VLE calculations are reported for mixtures containing a refrigerant and a polyol-ester lubricant over wide temperature and concentration ranges. The thermodynamic condition for LLE is checked. If two liquid phases are present, LLE is calculated and compared with experimental measurements.