Thermodynamic Properties of HFE-7300

Ethylene glycols are a group of versatile industrial solvents with broad applications across various sectors. Accurate thermodynamic modeling of these compounds is essential for enhancing their utilization and optimizing industrial processes. Among the advanced models available, the Statistical Associating Fluid Theory (SAFT) type equation of state (EoS) stands out for its effectiveness in capturing the thermodynamic behavior of complex fluids. This study employs the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs to model pure monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), and their mixtures. Furthermore, the predictive capabilities of these models are critically evaluated for polyethylene glycol 400 (PEG 400). The performance of the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs was evaluated for predicting key thermodynamic properties, including density, thermal expansion coefficient, isothermal compressibility, isobaric heat capacity, speed of sound, and saturated vapor pressure, for pure MEG, DEG, TEG, and PEG 400. Among the models, the PρT-SAFT demonstrated superior accuracy in modeling their properties. Subsequently, the volumetric properties and vapor–liquid equilibrium data of binary mixtures of MEG, DEG, and TEG were predicted using the same EoSs, without incorporating any binary interaction parameters. Under these conditions, the PρT-SAFT achieved the highest accuracy. Furthermore, predictions of the volumetric properties for the ternary mixture of MEG, DEG, and TEG also indicated that the PρT-SAFT outperformed the other models. The overall average absolute deviation percentages for the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs across all examined thermodynamic properties and systems were 7.0, 8.2, 22.2, and 30.2, respectively, confirming the robustness of the PρT-SAFT.

R-454B is an excellent choice for refrigeration systems due to its environmentally friendly profile. In this study, the thermophysical properties of R-454B refrigerant are predicted using molecular dynamics (MD) simulations coupled with a SAFT-based equation of state (EoS). Since experimental data on the thermophysical properties of R-454B are generally scarce in technical applications, exploring these properties is essential. In this work, the COMPASS force field is employed to develop the MD simulations. The saturated density, vapor pressure, and isobaric heat capacity of R-454B were simulated. The average ARD% for the isobaric heat capacity was approximately 7.66% over the temperature range of 273.15–303.15 K. The PC-SAFT equation of state (EoS) was coupled with MD simulation to predict the thermodynamic properties of R-454B across a broad range of pressures and temperatures. In this regard, the PC-SAFT model parameters were adjusted using the simulated saturated liquid density and vapor pressure data. The obtained PC-SAFT model parameters were utilized to predict the speed of sound, specific heat capacity, and Joule–Thomson coefficient of R-454B. The results indicate that the proposed model can satisfactorily predict the vapor and liquid thermophysical properties of R-454B. This methodology can be employed to estimate second-order derivative thermodynamic properties of novel refrigerants prior to synthesis, potentially reducing the costs and time associated with experimental development.

The isobaric and isochoric heat capacities of seven 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides, two 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imides, and two bis(1-alkyl-3-methylimidazolium) tetrathiocyanatocobaltates were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined by means of differential scanning calorimetry, whereas isochoric heat capacities were determined along with isothermal compressibilities indirectly by means of the acoustic method from the speed of sound and density measurements. Based on the experimental data, as expected, the isobaric heat capacity increases linearly with increasing alkyl chain length in the cation of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides and no odd and even carbon number effect is observed. After critical comparison of the obtained data with the available literature data, the most reliable values are recommended. It has been also...

Vapor-liquid equilibria and thermodynamic properties of saturated argon and krypton were calculated by semi-classical Monte Carlo simulations with the NpT + test particle method using abinitio potentials for the two-body and nonadditive three-body interactions. The NpT + test particle method was extended to the calculation of second-order thermodynamic properties, such as the isochoric and isobaric heat capacities or the speed of sound, of the saturated liquid and vapor by using our recently developed approach for the systematic calculation of arbitrary thermodynamic properties in the isothermal-isobaric ensemble. Generally, the results for all simulated properties agree well with experimental data and the current reference equations of state for argon and krypton. In particular, the results for the vapor pressure and for the density and speed of sound of the saturated liquid and vapor agree with the most accurate experimental data for both noble gases almost within the uncertainty of these data, a level of agreement unprecedented for many-particle simulations. This study demonstrates that the vapor-liquid equilibrium and thermodynamic properties at saturation of a pure fluid can be predicted by Monte Carlo simulations with high accuracy when the intermolecular interactions are described by state-of-the-art abinitio pair and nonadditive three-body potentials and quantum effects are accounted for.

PρT measurements of 3-aminopropan-1-ol and N-(2-hydroxyethyl)morpholine from (293.15 to 473.15) K and up to 40 MPa and modeling with modified Tait and PC-SAFT equations

Per- and poly-fluoroalkyl substances in agricultural contexts and mitigation of their impacts using biochar: A review

Bench scale incineration of polychlorotrifluoroethylene.

The isobaric and isochoric heat capacities of six disubstituted imidazolium-based ionic liquids with different anions and two trisubstituted imidazolium-based bis(trifluoromethylsulfonyl)imides were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined using differential scanning calorimetry. The isochoric heat capacities were determined indirectly by means of the acoustic method from the speed of sound and density measurements. Also, other connected with the speed of sound quantities such as isentropic and isothermal compressibilities as well as internal pressures were determined. The highest compressibilities show both trisubstituted imidazolium-based bis(trifluoromethylsulfonyl)imides whereas 1-ethyl-3-methylimidazolium thiocyanate shows the lowest compressibility. The critical comparison of the isobaric heat capacity data with the available literature data makes possible a recommendation of the most reliable heat capacity values. Analyzed predictive capability of two heat capacity models based on the group contribution method is poor in the case of the [C(CN)3]− anion. Additionally, based on the speeds of sound, the thermal conductivities were calculated using a modified Bridgman relation and compared with values estimated by a group contribution method. Here, the worst results are obtained in the case of [SCN]− anion.

Modeling heat capacity of saturated hydrocarbon in liquid phase over a wide range of temperature and pressure

Precise 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

Densities and isobaric heat capacities per unit volume have been measured for binary mixtures {x benzonitrile + (1 − x) octane} and {x benzonitrile + (1 − x) nonane} in the temperature ranges of (283.15 to 318.15) K and (283.15 to 313.15) K, respectively. Measurements covered the whole composition range at the ambient pressure. From these measured data, the excess molar volumes, excess isobaric thermal expansivities, and excess isobaric molar heat capacities were calculated and fitted with the Redlich−Kister equation. The excess molar volumes, excess isobaric thermal expansivities, and excess isobaric molar heat capacities of both systems were found to exhibit the S-shaped curves against the composition and the feature of the nonrandomness mixing. The dependences of these properties on the temperature and composition were analyzed and discussed in terms of the natures of the two pure components and the molecular interactions in the mixtures.

This chapter presents the features of the Enhanced-Predictive-PR78 equation of state (E-PPR78), a model highly suitable to perform “physical fluid screening” in power and refrigeration cycles. It enables, in fact, the accurate and predictive (i.e., without the need for its preliminary optimization by the user) determination of the thermodynamic properties of pure and multicomponent fluids usable in power and refrigeration cycles: hydrocarbons (alkanes, alkenes, alkynes, cycloalkane, naphthenic compounds, and so on), permanent gases (such as CO2 , N2 , H2 , He, Ar, O2 , NH3 , NO2/N2O4, and so on), mercaptans, fluorocompounds, and water. The EPPR78 equation of state is a developed form of the Peng-Robinson equation of state, which enables both the predictive determination of binary interaction parameters and the accurate calculation of pure fluid and mixture thermodynamic properties (saturation properties, enthalpies, heat capacities, volumes, and so on)

An equation of state is presented for the thermodynamic properties of propane that is valid for temperatures from the triple point temperature (85.525 K) to 650 K and for pressures up to 1000 MPa. The formulation can be used for the calculation of all thermodynamic properties, including density, heat capacity, speed of sound, energy, and saturation properties. Comparisons to available experimental data are given that establish the accuracy of calculated properties. The approximate uncertainties of properties calculated with the new equation are 0.01 % to 0.03 % in density below 350 K, 0.5 % in heat capacities, 0.03 % in the speed of sound between (260 and 420) K, and 0.02 % in vapor pressure above 180 K. Deviations in the critical region are higher for all properties except vapor pressure.

A new formulation for the thermodynamic properties of trifluoromethane (R-23) is presented. The formulation is valid for single-phase and saturation states for temperatures from the triple point (118.02 K) to 475 K, pressures up to 120 MPa, and densities up to 24.31 mol/dm3. The formulation includes a fundamental equation and ancillary functions for the estimation of saturation properties. The experimental data used to determine the fundamental equation included pressure–density–temperature (p–ρ–T), isobaric heat capacity (cp–p–T), isochoric heat capacity (cν–ρ–T), saturation heat capacity (cσ), speed of sound (w–p–T), and vapor pressure. A nonlinear regression algorithm was used to determine the constants and exponents of various functions within the formulation. Experimental data and values computed using the formulation are compared to verify the uncertainties in the calculated properties. The formulation presented may be used to compute densities to within ±0.1%, heat capacities to within ±0.5%, speed of sound to within ±0.5%, and vapor pressures to within ±0.2%, except near the critical point.

A joint project by the authors has resulted in two new thermodynamic property formulations for oxygen. The fundamental equation explicit in Helmholtz energy by Schmidt and Wagner has been used for the calculation of the property tables presented here, and for comparisons of calculated properties to the experimental data. The formulation of Stewart and Jacobsen is used in this paper in comparisons of properties calculated by the two formulations. These comparisons provide the basis for independent assessment of the accuracy of the available data and calculated properties. The procedures used in determining the formulations by Wagner and Schmidt, and by Stewart and Jacobsen were published earlier. The fundamental equation is valid for thermodynamic properties of oxygen from the freezing line to 300 K at pressures to 80 MPa. A separate vapor pressure equation and equations for the saturated liquid and saturated vapor densities and the ideal gas heat capacity are included. Functions for calculating internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp) and velocity of sound are also included. Tables of thermodynamic properties of oxygen are given within the range of validity of the fundamental equation. The fundamental equation reported here may be used to calculate densities with an uncertainty of 0.10 percent, heat capacities within 2.0 percent, and velocity of sound values within 1.0 percent. These uncertainty values are valid for the range outside of the critical region. Comparisons of calculated properties to experimental data are included to verify the accuracy of the formulation.