Properties Of Pure Fluids Research Articles

Vapor Pressure of Dichlorosilane, Trichlorosilane, and Tetrachlorosilane from 300 K to 420 K

The method for the preparation of elemental silicon of sufficient purity for the fabrication of electronic devices is by first converting silicon oxide to silicon–hydrogen-chloride compounds, purifying the material as a fluid mixture, and then converting the product to solid silicon. During the purification process a mixture of dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), and tetrachlorosilane or silicon tetrachloride (SiCl4) are formed with each of the components in significant quantities. Models that describe the vapor–liquid equilibrium behavior for the mixtures are required to design appropriate separation and purification processes. Pure fluid properties form the starting point for most mixture models, hence the importance of vapor pressures for the pure materials. In this work we report measurements of the vapor pressures for three of the most important fluids in the silicon production process, dichlorosilane, trichlorosilane, and tetrachlorosilane. Our results are compared with measurements ...

Gaussian-Charge Polarizable and Nonpolarizable Models for CO2.

A polarizable intermolecular potential model using three classical Drude oscillators on the atomic sites has been developed for CO2. The model is rigid with bond lengths and molecular geometries set to their experimental values. Electrostatic interactions are represented by three Gaussian charges connected to the molecular frame by harmonic springs. Nonelectrostatic interactions are represented by the Buckingham exponential-6 potential, with potential parameters optimized to vapor-liquid equilibria (VLE) data. A nonpolarizable CO2 model that shares the other ingredients of the polarizable model was also developed and optimized to VLE data. Gibbs ensemble Monte Carlo and molecular dynamics simulations were used to evaluate the two models with respect to a variety of thermodynamic and transport properties, including the enthalpy of vaporization, second virial coefficient, density in the one-phase fluid region, isobaric and isochoric heat capacities, radial distribution functions, self-diffusion coefficient, and shear viscosity. Excellent agreement between model predictions and experimental data was found for all properties studied. The polarizable and nonpolarizable models provide a similar representation of CO2 properties, which indicates that the properties of pure CO2 fluid are not strongly affected by polarization. The polarizable model, which has an order of magnitude higher computational cost than the nonpolarizable model, will likely be useful for the study of a mixture of CO2 and polar components for which polarization is important.

On the use of SAFT-VR Mie for assessing large-glide fluorocarbon working-fluid mixtures in organic Rankine cycles

By employing the SAFT-VR Mie equation of state, molecular-based models are developed from which the thermodynamic properties of pure (i.e., single-component) organic fluids and their mixtures are calculated. This approach can enable the selection of optimal working fluids in organic Rankine cycle (ORC) applications, even in cases for which experimental data relating to mixture properties are not available. After developing models for perfluoroalkane (n-C4F10+n-C10F22) mixtures, and validating these against available experimental data, SAFT-VR Mie is shown to predict accurately both the single-phase and saturation properties of these fluids. In particular, second-derivative properties (e.g., specific heat capacities), which are less reliably calculated by cubic equations of state (EoS), are accurately described using SAFT-VR Mie, thereby enabling an accurate prediction of important working-fluid properties such as the specific entropy. The property data are then used in thermodynamic cycle analyses for the evaluation of ORC performance and cost. The approach is applied to a specific case study in which a sub-critical, non-regenerative ORC system recovers and converts waste heat from a refinery flue-gas stream with fixed, predefined conditions. Results are compared with those obtained when employing analogue alkane mixtures (n-C4H10+n-C10H22) for which sufficient thermodynamic property data exist. When unlimited quantities of cooling water are utilized, pure perfluorobutane (and pure butane) cycles exhibit higher power outputs and higher thermal efficiencies compared to mixtures with perfluorodecane (or decane), respectively. The effect of the composition of a working-fluid mixture in the aforementioned performance indicators is non-trivial. Only at low evaporator pressures (<10bar) do the investigated mixtures perform better than the pure fluids. A basic cost analysis reveals that systems with pure perfluorobutane (and butane) fluids are associated with relatively high total costs, but are nevertheless more cost effective per unit power output than the fluid mixtures (due to the higher generated power). When the quantity of cooling water is constrained by the application, overall performance deteriorates, and mixtures emerge as the optimal working fluids.

Neutron Matter from Low to High Density

Neutron matter is an intriguing nuclear system with multiple connections to condensed matter and astrophysics. Considerable progress has been made over the past 20 years in exploring the properties of pure neutron fluids. We begin by reviewing research exploring the behavior of very low density neutron matter, which forms a strongly paired superfluid and is thus similar to cold Fermi atoms, although at energy scales that differ by many orders of magnitude. We then review the behavior of higher-density neutron matter, discussing research that ties the study of neutron matter to the determination of the properties of neutron-rich nuclei and neutron star crusts. Finally, we review the impact that neutron matter at even higher densities has on the mass–radius relation of neutron stars, thereby making contact with astrophysical observations.

The Extended Crossover Peng–Robinson Equation of State for Describing the Thermodynamic Properties of Pure Fluids

In this paper, a theoretical method has been introduced for developing the crossover Peng–Robinson (CPR) equation of state (EoS) which incorporates the non-classical scaling laws asymptotically near the critical point into a classical analytic equation further away from the critical point. The CPR EoS has been adopted to describe the thermodynamic properties of some pure fluids (normal alkanes from methane to n-butane and carbon dioxide) such as density, saturated pressure, isochoric heat capacity and speed of sound. Unlike the original method for the crossover transformation made by Chen et al. (Phys Rev A 42:4470–4484, 1990), we have proposed a procedure which adding an additional term into the crossover transformation to obtain the thermophysical properties at the critical point more exactly. It is shown that this new crossover method yields a satisfactory representation of the thermodynamic properties close to the critical point for pure fluids relative to the original PR EoS.

An Improvement to COSMO-SAC for Predicting Thermodynamic Properties

A modified COSMO-SAC model is presented to calculate thermodynamic properties of pure fluids and mixtures using statistical thermodynamics and the surface charge density of each compound obtained from a quantum mechanics (QM) calculation. The main differences from the previous models are that the new model includes a dispersion contribution in the mixture interaction, and is reparametrized using measured pure and mixture thermodynamic data simultaneously. With a single set of universal parameters, the new model provides higher accuracy than our previous models for predicting mixture thermodynamic properties while maintaining the same accuracy for pure compound thermodynamic properties. The overall root-mean-square deviation (RMSD) in the logarithms of partition coefficients for 992 octanol–water partitioning systems and 829 other solvent–water partitioning systems with this new model is reduced by about 10% compared to the results from previous models. Also, the agreement between the predicted and measure...

Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp

Over the last few decades, researchers have developed a number of empirical and theoretical models for the correlation and prediction of the thermophysical properties of pure fluids and mixtures treated as pseudo-pure fluids. In this paper, a survey of all the state-of-the-art formulations of thermophysical properties is presented. The most-accurate thermodynamic properties are obtained from multiparameter Helmholtz-energy-explicit-type formulations. For the transport properties, a wider range of methods has been employed, including the extended corresponding states method. All of the thermophysical property correlations described here have been implemented into CoolProp, an open-source thermophysical property library. This library is written in C++, with wrappers available for the majority of programming languages and platforms of technical interest. As of publication, 110 pure and pseudo-pure fluids are included in the library, as well as properties of 40 incompressible fluids and humid air. The source code for the CoolProp library is included as an electronic annex.

A modified MMM EOS for high-pressure PVT calculations of heavy hydrocarbons

A theoretical based cubic equation of state has been proposed (MMM EOS) by Mohsen-Nia (Mohsen-Nia et al., 1995) for calculation of pure fluid and mixture properties Z=(v+1.3191b)/(v−b)−a/[RT1.5(v+b)] In previous works, the superiority of the MMM has been shown over the vdW family of EOSs for PVT and VLE calculations. In this work, a new simple functional form for its attractive and repulsive parameters [a(T) and b(T)] is introduced. The proposed EOS is applied to vapor pressure and saturated density calculations of different pure fluids. Then, the proposed equation is used to calculate high-pressure PVT of heavy hydrocarbons. The performance of the proposed EOS for VLE calculations is examined against the corresponding experimental measurements for a number of binary mixtures and the results are compared with those obtained from the cubic EOSs frequently used for thermodynamic and fluid phase equilibrium calculations. The comparisons indicate the modified MMM EOS is quite suitable for property predictions of gas and liquid systems, especially for high-pressure PVT of heavy hydrocarbon systems of interest in the oil and gas industries.

Renewable Feedstocks in Green Solvents: Thermodynamic Study on Phase Diagrams of d-Sorbitol and Xylitol with Dicyanamide Based Ionic Liquids

Experimental and theoretical studies on thermodynamic properties of three ionic liquids based on dicyanamide anion (namely, 1-butyl-3-methylimidazolium dicyanamide, 1-butyl-1-methylpyrrolidinium dicyanamide, and 1-butyl-1-methylpiperidinium dicyanamide) and their binary mixtures with sugar alcohols (D-sorbitol and xylitol) were conducted in order to assess the applicability of the salts ionic liquids for dissolution of those biomass-related materials. Density and dynamic viscosity (at ambient pressure) of pure ionic liquids are reported in the temperature range from T = 293.15 to 363.15 K. Solid-liquid equilibrium phase diagrams in binary systems {sugar alcohol + ionic liquid} were measured with dynamic method up to the fusion temperature of sugar alcohol. The impact of the chemical structure of both the ionic liquid and sugar alcohol were established and discussed. For the very first time, the experimental solubility data were reproduced and analyzed in terms of equation of state rooted in statistical mechanics. For this purpose, perturbed-chain statistical associating fluid theory (PC-SAFT) was employed. In particular, new molecular schemes for the ionic liquids, D-sorbitol, and xylitol were proposed, and then the pure chemicals were parametrized by using available density and vapor pressure data. The model allowed accurate correlation of pure fluid properties for both ionic liquids and sugar alcohols, when the association term is taken into account. The results of solid-liquid equilibria modeling were also satisfactory. However, one or two adjustable binary corrections to the adopted combining rules were required to be adjusted in order to accurately capture the phase behavior. It was shown that a consistent thermodynamic description of extremely complex systems can be achieved by using relatively simple (but physically grounded) theoretical tools and molecular schemes.

Modeling the Vapor-Liquid Equilibrium of Mixtures Involving Noble Gases, Alkanes, and Refrigerants and some Ionic Liquids Using Perturbed Hard-Sphere Equation of State

The present study is a continuation of our previous work (S.M. Hosseini, J. Moghadasi, M.M. Papari, F. Fadaei Nobandegani, J. Mol. Liq. 160 (2011) 67-71) related to the examination of the ability of the perturbed hard- sphere equation of state (EOS) in predicting thermodynamic properties of pure fluid and mixtures.In our previous study, aperturbed hard-sphere equation of state was developed to predict pressure-volume-temperature-composition surfaces of pure and mixturesof ionic liquids (ILs). The present paper aims to extend the model to vapor-liquid equilibria of some binary mixtures consisting of ionic liquids, refrigerants, hydrocarbons, and monatomic fluids. The novelty of the present work is the application ofourperturbed hard-sphere equation of statetomodel the phase equilibria of various mixtures. The outcomes of the computation are compared with the experimental data. Our results demonstrate that this EOS can properly model phase equilibria of fluid mixtures with acceptable accuracies.

Thermodynamic properties of gold–water nanofluids using molecular dynamics

The physical behavior of a nanofluids is still not fully understood. This work focuses on the study and understanding of equilibrium thermodynamic properties of several gold–water nanofluids using molecular dynamics simulations. Three different systems are considered, where gold nanoparticles with diameters of 2.6, 5.8, and 6.6 nm are suspended in water for effective nanoparticle volume fractions of 1, 10, and 15 %, respectively. Novelties of this study are in the use of accurate force fields for modeling the inter- and intramolecular interactions of the components, and providing comprehensive thermodynamic properties of the nanofluids. The results are validated with the pure fluid and solid properties. Results indicate that the thermodynamics of the system does not behave as an ideal mixture, due to a combination of several factors such as liquid layering, anisotropicity, and other solid–liquid interfacial effects.

Application of the statistical associating fluid theory for potentials of variable range (SAFT-VR) coupled with renormalisation-group (RG) theory to model the phase equilibria and second-derivative properties of pure fluids

In earlier work, a methodology to couple SAFT-VR with an RG treatment (SAFT-VR+RG) for square-well chain and associating fluids was presented [E. Forte, F. Llovell, L.F. Vega, J.P.M. Trusler, A. Galindo, J. Chem. Phys. 134 (15) (2011) 154102]. The approach is based on a recursive procedure which begins with an initial free energy incorporating only contributions from short-wavelength density fluctuations, which are treated locally. The contribution from long-wavelength fluctuations is incorporated through the iterative procedure based on attractive interactions that incorporate the structure of the fluid following the ideas of perturbation theories and using a mapping that allows integration of the radial distribution function. The resulting SAFT-VR+RG theory provides an equation of state based on the classical SAFT-VR equation and yields the correct critical behaviour without the need for additional adjustable parameters. In this work, the application of this equation to real fluids is presented. The ability of the methodology to reproduce the phase behaviour close to and far from criticality solely through the standard SAFT-VR molecular parameters is demonstrated here. Molecular model parameters for a range of fluids, both non-associating and associating are presented, including the homologous series of n-alkanes, benzene, carbon dioxide, water, light alcohols, ammonia, hydrogen fluoride and hydrogen sulphide. These were determined by comparison with experimental data for vapour pressure and saturated liquid density. Furthermore, the models presented are used to predict second derivative properties for these compounds. Deviations compared with the original SAFT-VR equation are discussed in order to assess further the improvements introduced by the coupled theory to predict these properties. The critical exponents α, β, γ and δ have also been obtained for a number of these fluids and found to be in good agreement with the universal values of the three-dimensional Ising model.

The Patel–Teja and the Peng–Robinson EoSs performance when Soave alpha function is replaced by an exponential function

A comparative study was made to establish how is altered the performance of Patel–Teja EoS and Peng–Robinson EoS, to represent thermodynamic properties of saturated pure fluids when the alpha function of Soave is substituted by an exponential function with one, two or three parameters. Results show that the Soave function should be replaced by a two parameter exponential function to get adequate representation of the vapor pressure and the saturated vapor volume of pure substances; especially in the low pressure zone (1–101.325kPa). Additionally the performance of equations of state to represent saturated liquid volume and vaporization enthalpy was found practically independent of the alpha function. Comparison between the two equations of state, show that Patel–Teja EoS is superior than Peng–Robinson EoS to represent the saturated liquid volume of pure substances with critical compressibility factor lower than 0.25 or higher than 0.285. Also it has been demonstrated that using the two-parameter alpha function of Heyen with the Wong–Sandler-NRTL mixing rules the capability of cubic EoS to represent the vapor liquid equilibria below 1atm for alcohol/alkane and alcohol/aromatic systems can be improved.

An improved generalized three-parameter cubic equation of state for pure fluids

An improved simple generalized three-parameter cubic equation of state for pure fluids is proposed to estimate pure component fluid properties by incorporating substance dependent epsilon-function and almost substance independent sigma-function in the generic cubic equation of state, followed by temperature and acentric factor dependent attractive term. The proposed cubic equation of state is utilized to predict critical compressibility factor, liquid molar volume, vapor molar volume, and pure component vapor pressure for several simple hydrocarbons and fatty acid of methyl esters, and the predicted properties are compared with the actual values. In this study, most of the pure fluid properties are considered from literature; however experimentation is carried out for few fatty acid of methyl esters to determine pure fluid vapor pressure at elevated temperature and pressure. The proposed cubic equation of state is found to be accurate in predicting both literature reported and experimentally determined pure fluid properties. The overall performance of the proposed cubic equation of state is also compared with commonly used cubic equations of state and is found to be superior for predicting critical compressibility factors and other pure fluid properties.

Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals

Ferronematic materials composed of 4-cyano-4′-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field.

Comparative study of eight cubic equations of state for predicting thermodynamic properties of alkanes

AbstractPrecise descriptions of the thermodynamic properties of pure fluids require accurate definition of vapour–pressure and phase volumes as well as residual volumes, enthalpies and entropies. While carefully fitted multi‐parameter equations of state (EOS), such as Benedict–Webb–Rubin–Starling fulfil these requirements, cubic EOSs usually do not. On the other hand, cubic EOSs are widely used in the oil industry, due to their simplicity and reliability in most vapour–liquid equilibrium calculations. For thermal oil recovery processes and the natural gas industry, the choice of EOS becomes important for predicting thermodynamic properties, such as isobaric and isochoric heat capacities, sound velocity and the Joule–Thomson coefficient. In this study, eight cubic EOSs which most of them are used in commercial reservoir simulators are selected for evaluation of their capability in the prediction of second‐order derivative thermodynamic properties at different temperatures and pressures, using pure components frequently found in petroleum and natural gas mixtures. It is shown that none of the cubic EOSs could accurately predict all of the stated parameters, especially below the critical point. All EOSs failed to show the extrema in the derivative properties. However, among these equations the Yu–Lu and Schmidt–Wenzel EOSs were found to have more reliable predictions in most of the cases. © 2011 Canadian Society for Chemical Engineering

Study on Hydroxylammonium-Based Ionic Liquids. I. Characterization

Two selected ammonium-based ionic liquids, 2-hydroxyethyltrimethylammonium L-(+)-lactate and tris(2-hydroxyethyl)methylammonium methylsulfate, were fully characterized. The most relevant thermophysical properties of pure fluids were measured and analyzed as a function of temperature. Structural features were inferred from solvatochromic and Fourier transform infrared (FTIR) studies. Moisture absorption ability was also studied by gravimetric, spectroscopic, and Karl Fischer methods. Likewise, the water effect on fluids properties was analyzed. Polarity was studied by approaches based on solvatochromic measurements and on the water effect on FTIR spectra. Moreover, as computational work, quantum chemistry and molecular dynamics simulation methods were used to analyze the main molecular-level structural features in these fluids. The work is divided into two parts; in this first paper, the main objective is fully characterizing these ionic liquids in the pure state, and in the second paper CO(2) absorption will be analyzed, therefore leading to a deep knowledge of factors controlling structuring, properties, and CO(2) absorption for this family of ionic liquids in comparison with available information for other relevant types of ionic liquids.

Ms2: A molecular simulation tool for thermodynamic properties

This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of bulk fluids in equilibrium consisting of small electro-neutral molecules. ms2 features the two main molecular simulation techniques, molecular dynamics (MD) and Monte-Carlo. It supports the calculation of vapor–liquid equilibria of pure fluids and multi-component mixtures described by rigid molecular models on the basis of the grand equilibrium method. Furthermore, it is capable of sampling various classical ensembles and yields numerous thermodynamic properties. To evaluate the chemical potential, Widomʼs test molecule method and gradual insertion are implemented. Transport properties are determined by equilibrium MD simulations following the Green–Kubo formalism. ms2 is designed to meet the requirements of academia and industry, particularly achieving short response times and straightforward handling. It is written in Fortran90 and optimized for a fast execution on a broad range of computer architectures, spanning from single processor PCs over PC-clusters and vector computers to high-end parallel machines. The standard Message Passing Interface (MPI) is used for parallelization and ms2 is therefore easily portable to different computing platforms. Feature tools facilitate the interaction with the code and the interpretation of input and output files. The accuracy and reliability of ms2 has been shown for a large variety of fluids in preceding work. Program summary Program title: ms2 Catalogue identifier: AEJF_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEJF_v1_0.html Program obtainable from: CPC Program Library, Queenʼs University, Belfast, N. Ireland Licensing provisions: Special Licence supplied by the authors No. of lines in distributed program, including test data, etc.: 82 794 No. of bytes in distributed program, including test data, etc.: 793 705 Distribution format: tar.gz Programming language: Fortran90 Computer: The simulation tool ms2 is usable on a wide variety of platforms, from single processor machines over PC-clusters and vector computers to vector-parallel architectures. (Tested with Fortran compilers: gfortran, Intel, PathScale, Portland Group and Sun Studio.) Operating system: Unix/Linux, Windows Has the code been vectorized or parallelized?: Yes. Message Passing Interface (MPI) protocol Scalability. Excellent scalability up to 16 processors for molecular dynamics and >512 processors for Monte-Carlo simulations. RAM: ms2 runs on single processors with 512 MB RAM. The memory demand rises with increasing number of processors used per node and increasing number of molecules. Classification: 7.7, 7.9, 12 External routines: Message Passing Interface (MPI) Nature of problem: Calculation of application oriented thermodynamic properties for rigid electro-neutral molecules: vapor–liquid equilibria, thermal and caloric data as well as transport properties of pure fluids and multi-component mixtures. Solution method: Molecular dynamics, Monte-Carlo, various classical ensembles, grand equilibrium method, Green–Kubo formalism. Restrictions: No. The system size is user-defined. Typical problems addressed by ms2 can be solved by simulating systems containing typically 2000 molecules or less. Unusual features: Feature tools are available for creating input files, analyzing simulation results and visualizing molecular trajectories. Additional comments: Sample makefiles for multiple operation platforms are provided. Documentation is provided with the installation package and is available at http://www.ms-2.de. Running time: The running time of ms2 depends on the problem set, the system size and the number of processes used in the simulation. Running four processes on a “Nehalem” processor, simulations calculating VLE data take between two and twelve hours, calculating transport properties between six and 24 hours.

Thermodynamic properties of gold–water nanolayer mixtures using molecular dynamics

The physical behavior of a fluid in contact with solid layers is still not fully understood. The present work focuses on the study and understanding of thermodynamic and structural properties of gold–water nanolayer mixtures using molecular dynamics simulations. Two different systems are considered, where approximately 1,700 water molecules are confined between gold nanolayers with separations of 7.4 and 6.2 nm, respectively. Novelties of the present work are in the use of accurate force fields for modeling the inter- and intra-molecular interactions of the components, and providing comprehensive thermodynamic properties of the mixtures. The results are validated by examination of the pure fluid and pure solid properties. Results indicate that the thermodynamics of the system does not behave as an ideal mixture. The structure of the pure fluid is also analyzed and compared against the structure of the confined fluid in the mixture. Anisotropicity is observed in the fluid structure close to the surface of the nanolayer. Higher ordering and higher flux are detected in the fluid molecules close to the fluid–solid interface. Unusual thermodynamic behavior, anisotropicity, liquid layering, and higher interfacial fluid flux could be just some of the factors leading to the enhanced energy transport observed in mixtures involving at least one nanoscale component, such as nanofluids.

Liquid–liquid phase equilibrium of (piperidinium-based ionic liquid + an alcohol) binary systems and modelling with NRHB and PCP-SAFT

The phase diagrams for binary systems of {1-propyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide [PMPIP][NTf 2] + an alcohol (butan-1-ol, pentan-1-ol hexan-1-ol, heptan-1-ol, octan-1-ol, decan-1-ol and undecan-1-ol} have been determined at atmospheric pressure using a dynamic method. The influence of an alcohol chain length is discussed for this ionic liquid (IL). A systematic decrease in the solubility is observed with an increase of the alkyl chain length of an alcohol. Liquid + liquid phase equilibrium (LLE) with an upper critical solution temperature was observed. The phase diagrams reported are compared to systems published earlier with the 1-alkyl-1-methylpiperidinium-based ionic liquid. The basic thermal properties of the pure IL, i.e. melting temperature and the enthalpy of fusion, the glass transition temperature and heat capacity at melting temperature have been measured using a differential scanning microcalorimetry technique. The density of [PMPIP][NTf 2] as a function of temperature was measured. The results of the LLE correlation with two models viz. the lattice theory based on non-random hydrogen bonding (NRHB) and the Perturbed-Chain Polar Statistical Associating Fluid Theory (PCP-SAFT) are presented. Both models are capable of describing pure fluid properties of IL (densities and solubility parameters) by using one set of parameters and the LLE in binary systems. This is to our knowledge the first paper presenting the SAFT modelling of binary LLE in ionic liquid systems.