Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf)

The fluorinated propene isomer R1243zf (3,3,3-trifluoroprop-1-ene, CF₃CFCH₂, CAS number 677-21-4) is a potential alternative refrigerant with short atmospheric lifetime, low-GWP, and low acute toxicity; however, because of its flammability it is being considered primarily as a component in blends. In this paper, 302 subcooled liquid density data and 101 vapor phase PvT data are presented. The subcooled liquid density data are measured for eight isotherms, evenly separated approximately from 283 K to 353 K, for pressures from close to saturation to 35 MPa and the vapor phase PvT data are measured for six isochores for temperatures approximately from 278 K to 368 K and for pressures approximately from 260 kPa to 912 kPa. In addition, a saturated liquid density correlation, a Tait correlation for the subcooled liquid density data, and a Martin–Hou Equation of State for the vapor phase PvT data are presented.     

Compressed Liquid Densities and Helmholtz Energy Equation of State for Fluoroethane (R161)

In this study, compressed liquid densities of Fluoroethane (R161, CAS No. 353-36-6) were measured using a high-pressure vibrating-tube densimeter over the temperature range from (283 to 363) K with pressures up to 100 MPa. A Helmholtz energy equation of state for R161 was developed from these density measurements and other experimental thermodynamic property data from the literature. The formulation is valid for temperatures from the triple point temperature of 130 K to 420 K with pressures up to 100 MPa. The approximate uncertainties of properties calculated with the new equation of state are estimated to be 0.25 % in density, 0.2 % in saturated liquid density between 230 K and 320 K, and 0.2 % in vapor pressure below 350 K. Deviations in the critical region are higher for all properties. The extrapolation behavior of the new formulation at high temperatures and high pressures is reasonable.     

Equation of State for the Thermodynamic Properties of 1,1,2,2,3-Pentafluoropropane (R-245ca)

An equation of state for the calculation of the thermodynamic properties of 1,1,2,2,3-pentafluoropropane (R-245ca), which is a hydrofluorocarbon refrigerant, is presented. The equation of state (EOS) is expressed in terms of the Helmholtz energy as a function of temperature and density, and can calculate all thermodynamic properties through the use of derivatives of the Helmholtz energy. The equation is valid for all liquid, vapor, and supercritical states of the fluid, and is valid from the triple point to 450 K, with pressures up to 10 MPa. Comparisons to experimental data are given to verify the stated uncertainties in the EOS. The estimated uncertainty for density is 0.1 % in the liquid phase between 243 K and 373 K with pressures up to 6.5 MPa; the uncertainties increase outside this range, and are unknown. The uncertainty in vapor-phase speed of sound is 0.1 %. The uncertainty in vapor pressure is 0.2 % between 270 K and 393 K. The uncertainties in other regions and properties are unknown due to a lack of experimental data.     

New Fundamental Equations of State with a Common Functional Form for 2,3,3,3-Tetrafluoropropene (R-1234yf) and <Emphasis Type="Italic">trans</Emphasis>-1,3,3,3-Tetrafluoropropene (R-1234ze(E))

New fundamental equations of state explicit in the Helmholtz energy with a common functional form are presented for 2,3,3,3-tetrafluoropropene (R-1234yf) and trans-1,3,3,3-tetrafluoropropene (R-1234ze(E)). The independent variables of the equations of state are the temperature and density. The equations of state are based on reliable experimental data for the vapor pressure, density, heat capacities, and speed of sound. The equation for R-1234yf covers temperatures between 240 K and 400 K for pressures up to 40 MPa with uncertainties of 0.1 % in liquid density, 0.3 % in vapor density, 2 % in liquid heat capacities, 0.05 % in the vapor-phase speed of sound, and 0.1 % in vapor pressure. The equation for R-1234ze(E) is valid for temperatures from 240 K to 420 K and for pressures up to 15 MPa with uncertainties of 0.1 % in liquid density, 0.2 % in vapor density, 3 % in liquid heat capacities, 0.05 % in the vapor-phase speed of sound, and 0.1 % in vapor pressure. Both equations exhibit reasonable behavior in extrapolated regions outside the range of the experimental data.     

Thermodynamic properties of HFO-1336mzz(E) (trans-1,1,1,4,4,4-hexafluoro-2-butene) at saturation conditions

The thermodynamic properties of HFO-1336mzz(E) (trans-1,1,1,4,4,4-hexafluoro-2-butene) were determined. The critical point was ascertained by visual observation of the meniscus disappearance within an optical cell. The critical temperature, critical density, and critical pressure were determined to be 403.37 ± 0.03 K, 515.3 ± 5.0 kg m⁻³, and 2766.4 ± 4.5 kPa, respectively. Vapor pressures were also measured at temperatures ranging from 323 K (50 °C) to the critical temperature, and were correlated using the Wagner-type equation. The acentric factor and normal boiling point were determined to be 0.4053 and 280.58 K (7.43 °C), respectively, using the vapor pressure correlation. Based on the critical parameters and the acentric factor, saturated vapor densities and liquid densities were estimated using the Peng–Robinson equation and the Hankinson–Thomson equation, respectively. The heat of vaporization was also calculated from the Clausius–Clapeyron equation.     

Equation of State for the Thermodynamic Properties of <Emphasis Type="Italic">trans</Emphasis>-1,3,3,3-Tetrafluoropropene [R-1234ze(E)]

An equation of state for the calculation of the thermodynamic properties of the hydrofluoroolefin refrigerant R-1234ze(E) is presented. The equation of state (EOS) is expressed in terms of the Helmholtz energy as a function of temperature and density. The formulation can be used for the calculation of all thermodynamic properties through the use of derivatives of the Helmholtz energy. Comparisons to experimental data are given to establish the uncertainty of the EOS. The equation of state is valid from the triple point (169 K) to 420 K, with pressures to 100 MPa. The uncertainty in density in the liquid and vapor phases is 0.1 % from 200 K to 420 K at all pressures. The uncertainty increases outside of this temperature region and in the critical region. In the gaseous phase, speeds of sound can be calculated with an uncertainty of 0.05 %. In the liquid phase, the uncertainty in speed of sound increases to 0.1 %. The estimated uncertainty for liquid heat capacities is 5 %. The uncertainty in vapor pressure is 0.1 %.     

Experimental Study of the Density and Viscosity of n-Heptane at Temperatures from 298 K to 470 K and Pressure upto 245 MPa

The density and viscosity of $n$ -heptane have been simultaneously measured over the temperature range from 298 K to 470 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of $k= 2$ is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid $n$ -heptane. Theoretically based Arrhenius–Andrade and Vogel–Tamman–Fulcher type equations with pressure-dependent coefficients were used to describe the temperature and pressure dependences of the measured viscosities for liquid $n$ -heptane. The measured values of the density and viscosity were compared in detail with reported data and with the values calculated from a reference EOS and correlation models for the viscosity.     

Thermodynamic properties of HFC-32 (difluoromethane)

An 18-coefficient modified Benedict–Webb–Rubin equation of state of HFC-32 (difluoromethane) has been developed, based on the updated available PVT measurements, heat capacity measurements and speed of sound measurements. Correlations of vapor pressure and saturated liquid density are also presented. The correlations have been developed based on the reported experimental saturation properties data. This equation of state is effective both in the superheated gaseous phase and compressed liquid phase at pressures up to 70 MPa, densities to 1450 kg/m³, and temperatures from 150 to 475 K, respectively.     

Experimental Measurement and Thermodynamic Modeling of the Solubility of Carbon Dioxide in Aqueous Alkanolamine Solutions in the High Gas Loading Region

The solubility of carbon dioxide in aqueous alkanolamine solutions was investigated in the high gas loading region based on experimental measurements and thermodynamic modeling. An experimental phase equilibrium study was performed to evaluate the absorption of carbon dioxide in aqueous solutions of five representative alkanolamines, including monoethanolamine, diethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol and piperazine. The carbon dioxide loadings of these solutions were determined for a wide range of pressures (62.5 kPa to 4150 kPa), temperatures (303.15 K to 343.15 K) and alkanolamine concentrations (2 M to 4 M). The results were found to be largely consistent with those previously reported in the literature. Furthermore, a hybrid Kent–Eisenberg model was developed for the correlation of the experimental data points. This new model incorporated an equation of state/excess Gibbs energy model for determining the solubility of carbon dioxide in the high-pressure–high gas loading region. This approach also used a single correction parameter, which was a function of the alkanolamine concentration. The results of this model were in excellent agreement with our experimental results. Most notably, this model was consistent with other reported values from the literature.     

Estimation of Density as a Function of Temperature and Pressure for Imidazolium-Based Ionic Liquids Using a Multilayer Net with Particle Swarm Optimization

The liquid density of imidazolium-based ionic liquids has been estimated using a combined method that includes an artificial neural network and a simple group contribution method. A total of 1736 data points of density at several temperatures and pressures, corresponding to 131 ionic liquids, have been used to train the neural network developed with particle swarm optimization. To discriminate among the different substances, the molar mass and the structure of the molecule were given as input variables. Then, new values of density as a function of temperature and pressure for 33 other ionic liquids (426 data points) have been predicted and the results compared to experimental data from the literature. The results show that the chosen artificial neural network with particle swarm optimization and the group contribution method represent an excellent alternative for the estimation of the liquid density of imidazolium-based ionic liquids with acceptable accuracy (AARD=0.44; R ² = 0.9934), for a wide range of temperatures and pressures (258 K to 393K and 99kPa to 206,940kPa).     

Thermal conductivity of the new refrigerants R134a,R152a,and R123 measured by the transient hot-wire method

Thermal-conductivity measurements are reported for the new refrigerants R134a, R152a und R123. Transient hot-wire experiments were performed which cover both the liquid and vapor states at temperatures and pressures ranging from?=?20°C to 90°C and fromp=0.1 bar to 60 bar respectively. The results are correlated with density and temperature. In addition temperature dependent correlations are presented for (i) saturated liquid, (ii) saturated vapor, (iii) ideal gas (which equals approximately vapor state at ambient pressure). Finally the results are compared with data from the literature and also with the thermal conductivities of R12 and R11.     

Ab Initio Calculated Results Require New Formulations for Properties in the Limit of Zero Density: The Viscosity of Methane ($$\hbox {CH}_{4}$$)

A wide-ranging formulation for the viscosity of methane in the limit of zero density is presented. Using ab initio calculated data of Hellmann et al. (J Chem Phys 129, 064302, 2008) from 80 K to 1500 K, the functional form was developed by guided symbolic regression with the constraints of correct extrapolation to \(T \rightarrow 0\) and in the high-temperature limit. The formulation was adjusted to the recalibrated experimental data of May et al. (Int J Thermophys 28, 1085–1110, 2007) so that these are represented within their estimated expanded uncertainty of 0.053 % (\(k = 2\)) in their temperature range from 210.756 K to 391.551 K. Based on comparisons with original data and recalibrated viscosity ratio measurements, the expanded uncertainty of the new correlation is estimated outside this temperature range to be 0.2 % to 700 K, 0.5 % to 1100 K, 1 % to 1500 K, and physically correct at higher temperatures. At temperatures below 210 K, the new correlation agrees with recalibrated experimental data within 0.3 % down to 150 K. Hellmann et al. estimated the expanded uncertainty of their calculated data at 1 % to 80 K. The new formulation extrapolates without a singularity to \(T\rightarrow 0\).     

Study on Isochoric Specific Heat Capacity of Liquid R-410A and HFE-347pcf2

The isochoric heat capacity (c _v ) of R-410A [a mixture of 49.81 mass% difluoromethane (HFC-32) + 50.19 mass% pentafluoroethane (HFC-125)] and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethylether (HFE-347pcf2) was measured at temperatures from 277 K to 400 K and at pressures up to 30 MPa. The reported density measurements for R-410A and HFE-347pcf2 are in the single-phase region and cover a density range above 0.92 g·cm^?3 and 1.33 g·cm^?3, respectively. The measured data of R-410A are compared with data reported by other researchers. Also, the measured data of R-410A are examined with an available equation of state. As a result, it is found that the present c _v data for R-410A agree well with those by other researchers and the calculated values with the equation of state in the measurement range except near the critical isochore.     

Compressed liquid speed of sound measurements of cis-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(Z))

In this paper, 38 speed of sound measurements in the compressed liquid phase of a high purity sample of the novel alternative working fluid cis-1,3,3,3-tetrafluoroprop-1-ene (R-1234ze(Z)) are reported along five isotherms, ranging from 273.15 K to 333.15 K for pressures up to 25 MPa. The experimental technique is based on a double pulse-echo method resulting in an expanded uncertainty less than 0.05% at the 95% confidence level over the entire thermodynamic space.     

Density of Vapor and Liquid Pentafluorobenzene Along the Saturation Line

The density of vapor and liquid pentafluorobenzene along the liquid–vapor coexistence curve has been studied by a gamma-ray attenuation technique over the temperature range from 293.5K to 530.9K. According to measurements, the coordinates of the critical point are T _C = (531.04 ± 0.05) K and ρ _C = (518.8 ± 2) kg · m^?3. The critical exponent β of the coexistence curve equals 0.345 ± 0.005. The results of our measurements were compared with data available in the literature. The height dependence of the density of a two-phase sample was investigated in relation to the temperature and time. These experiments made it possible to determine the isothermal compressibility of liquid and vapor phases near the critical point.     

Correlations for the viscosity of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E))

Due to concerns about global warming, there is interest in 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) as potential replacements for refrigerants with high global warming potential (GWP). In this paper we survey available data and provide viscosity correlations that cover the entire fluid range including vapor, liquid, and supercritical regions. The correlation for R1234yf is valid from the triple point (220 K) to 410 K at pressures up to 30 MPa, and the correlation for R1234ze(E) is valid from the triple point (169 K) to 420 K at pressures up to 100 MPa. The estimated uncertainty for both correlations at a 95% confidence level is 2% for the liquid phase over the temperature range 243 K to 363 K at pressures to 30 MPa, and 3% for the gas phase at atmospheric pressure.     

An Improved Computational Method for the Calculation of Mixture Liquid–Vapor Critical Points

Knowledge of critical points is important to determine the phase behavior of a mixture. This work proposes a reliable and accurate method in order to locate the liquid–vapor critical point of a given mixture. The theoretical model is developed from the rigorous definition of critical points, based on the SRK equation of state (SRK EoS) or alternatively, on the PR EoS. In order to solve the resulting system of \(C+2\) nonlinear equations, an improved method is introduced into an existing Newton–Raphson algorithm, which can calculate all the variables simultaneously in each iteration step. The improvements mainly focus on the derivatives of the Jacobian matrix, on the convergence criteria, and on the damping coefficient. As a result, all equations and related conditions required for the computation of the scheme are illustrated in this paper. Finally, experimental data for the critical points of 44 mixtures are adopted in order to validate the method. For the SRK EoS, average absolute errors of the predicted critical-pressure and critical-temperature values are 123.82 kPa and 3.11 K, respectively, whereas the commercial software package Calsep PVTSIM’s prediction errors are 131.02 kPa and 3.24 K. For the PR EoS, the two above mentioned average absolute errors are 129.32 kPa and 2.45 K, while the PVTSIM’s errors are 137.24 kPa and 2.55 K, respectively.     

Solubility of Baicalein in Different Solvents from (287 to 323) K

The solubility of baicalein in methanol, ethanol, n-propanol, propan-2-ol, n-butanol, isobutyl alcohol, 1,3-propanediol, and ethyl acetate was measured from (287 to 323) K at atmospheric pressure using high-performance liquid chromatography analysis. Its corresponding (solid + liquid) equilibrium data should provide essential support for the purification of baicalein. The solubility data were correlated by the modified Apelblat equation and the van’t Hoff equation. The solubility data indicated that ethyl acetate might be the best choice for purification of baicalein among these solvents. The correlated results showed that the two equations were both in good agreement with the experimental values, but the correlation of the modified Apelblat equation had smaller deviations than those of the van’t Hoff equation.     

Density,Surface Tension,and Viscosity of CMSX-4<Superscript>®</Superscript> Superalloy

The surface tension, density, and viscosity of the Ni-based superalloy CMSX-4^® have been determined in the temperature ranges of 1,650–1,850 K, 1,650–1,950 K, and 1,623–1,800 K, respectively. Each property has been measured in parallel by different techniques at different participating laboratories, and the results are compared with the aim to improve the reliability of data and to identify recommended values. The following relationships have been proposed: density-ρ (T) [kg· m^?3] = 7,876 ? 1.23(T ? 1,654 K); surface tension-γ (T) [mN·m^?1] = 1,773 ? 0.56 (T ? 1, 654 K); viscosity-η (T) [mPa·s] = 8.36 ? 1.82 × 10^?2(T ? 1,654 K). For a comparison, surface-tension measurements on the Al-88.6 at% Ni liquid alloy with the same Al-content as the CMSX-4^® alloy were also performed. In addition, the surface tension and density have been theoretically evaluated by different models, and subsequently compared with new experimental data as well as with those reported in the literature. The surface-tension experimental data for the liquid CMSX-4^® alloy were found to be close to that of the Al-88.6 at% Ni alloy which is consistent with results from the compound formation model (CFM).     

A Thermodynamic Equation of State for Pentafluoroethane (R-125)

We developed a fundamental equation of state for pentafluoroethane (R-125, CHF₂CF₃) which is represented in terms of a non-dimensional Helmholtz free energy. The equation has been established on the basis of selected measurements of the pressure-density-temperature relation, speed of sound, heat capacities, and saturation properties. Linear and non-linear regression analysis was employed to determine the functional form and the numerical parameters. The equation represents all the thermodynamic properties of R-125 in the liquid and gaseous phases for temperatures between the triple point and 470 K, and pressures up to 35 MPa. The uncertainties are estimated to be about ±0.05% or 0.1 kPa for the vapor pressure, ± 0.05 % for the liquid and vapor densities, about ± 1 % for the isobaric and isochoric heat capacities in the liquid, and ± 0.5 % or ± 0.02 % for the speed of sound in the liquid and vapor, respectively.