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Experimentally determined critical temperatures (Tc) and critical pressures (Pc) are reported for 64 compounds. In addition, the critical volume (Vc) has been experimentally determined for 14 of these compounds. The compounds in this study are of industrial interest in process design, simulation, and safety. These data also extend our understanding of and ability to predict these properties from group contribution methods.

For 1-pentene and the three branched C5H10 isomers (2-methylbut-1-ene, 3-methylbut-1-ene, and 2-methylbut-2-ene), vapor pressures and vapor–liquid critical properties were determined, thus filling several gaps in the thermodynamic database for these compounds. Using a static titanium autoclave with sapphire windows for high temperature and pressure determinations, vapor pressures and critical temperatures, pressures, and density data were measured. The experimental data were used to fit parameters for the Wagner vapor pressure equation and compared to available literature data. The consistency of the critical values was checked with the critical surface equation.

The collection, scope, utility, and development of a comprehensive database with published experimental thermophysical properties of nanofluids is described in this paper. The collected data target nanofluids composed of a base fluid, which can be a pure compound or a binary mixture, and a single type of nanoparticle. The available experimental data in published scientific literature up to date in the field of nanofluids has been collected and organized to provide easy access to knowledge on the thermophysical behavior of nanofluids. The database contains a total of 307 datasets with 8118 data records of thermophysical properties of nanofluids, covering 13 types of base fluids, and 19 nanoparticle types. The collected experimental data include five thermodynamic properties (i.e. density, isobaric heat capacity, vapor pressure, speed of sound, and vaporization enthalpy) and two transport properties (i.e. thermal conductivity, and dynamic viscosity). The first release of this database is accesible for free under the host of the Dortmund Databank. An analysis of the consistency of the data, and challenges encountered during the data collection is provided.

In this work, heat capacities for three linear siloxanes (hexamethyl disiloxane (MM), octamethyltrisiloxane (MDM), and decamethyltetrasiloxane (MD2M)) in the temperature range of 205.15–395.15 K and for two cyclic siloxanes (octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5)) in the temperature range of 288.15–443.15 K have been measured with the help of a Tian–Calvert calorimeter. Furthermore, vapor pressures for the five mentioned compounds in the temperature range of 250–620 K and pressures from 2 mbar to 1 bar have been determined with the help of a Scott ebulliometer. The prediction of the heat capacities using the group contribution equation of state VTPR were improved by fitting the Twu parameters simultaneously to the new vapor pressure and heat capacity data. In addition, melting temperatures and heat of fusions for these five siloxanes have been measured using a differential scanning calorimeter (DSC). Furthermore, density measurements for the three linear siloxanes (MM, MDM...

In this work the accuracy of the prediction of Joule–Thomson coefficients for the gases CO2 and Ar and the binary systems CO2–Ar and CH4–C2H6 was examined using the group contribution equation of state VTPR. Furthermore the experimental and correlated data of Joule–Thomson inversion curves of a few compounds including carbon dioxide, nitrogen, benzene, toluene, methane, ethane, ethylene, propyne, and SF6 were compared with the results of the group contribution equation of state VTPR, the Soave–Redlich–Kwong (SRK), the Peng–Robinson (PR) and the Helmholtz equation of state (HEOS). Moreover, Joule–Thomson inversion curves for pure fluids, binary (CH4–C2H6, N2–CH4, CO2–CH4), and ternary systems (CO2–CH4–N2, CH4–C2H6–N2, CO2–CH4–C2H6) were calculated with VTPR and compared to the results of SRK, PR, HEOS and the molecular simulation results of Vrabec et al. It was found that the calculated values for the Joule–Thomson coefficients and Joule–Thomson inversion curves are in good agreement with the experimental findings.

Thermal conductivities have been measured for three linear siloxanes [hexamethyl disiloxane (MM), octamethyltrisiloxane (MDM), decamethyltetrasiloxane (MD2M)], two cyclic siloxanes [octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5)], and a mixture of 50 mass % MDM + 50 mass % MD2M in the temperature range from 290 to 520 K and the pressure range from 500 to 10000 kPa using the transient hot wire method and correlated with a temperature–pressure–thermal conductivity relationship. Moreover, the thermal conductivities at atmospheric pressure were measured for MM, D4, D5, and MD2M. The data were compared with the available data from the literature for four compounds. Additionally, the viscosities of the five siloxanes were measured in the temperature range from 238 to 378 K at atmospheric pressure using a rotational Stabinger viscometer.

In this paper densities for THF (tetrahydrofuran) and THF + water mixtures measured with the help of the Anton Paar DMA HPM vibrating tube densimeter are reported. The pure component densities of tetrahydrofuran measured in the temperature range from 278 to 437 K and pressures up to 130 MPa were correlated with the TRIDEN-System. Additionally densities of the binary mixture tetrahydrofuran + water were measured for 6 different concentrations in a temperature range from 288 to 338 K and up to 130 MPa. Excess volumes ( v E ) of the mixture were determined using the own correlation of the tetrahydrofuran densities and the equation of state (EoS) for water by Wagner and Prus. Redlich–Kister polynomials were used to fit the v E -data . Additionally in this work it was checked if the vibrating tube densimeter allows the determination of the miscibility gap for the system THF–water as a function of temperature and pressure.

It is a widely unknown or unrecognized fact that the vapor−liquid critical points of pure compounds and also of mixtures form a sail-like surface in the three-dimensional space of temperature, pressure, and molar volume or density. The available experimental critical points of all pure compounds lie on or near that critical surface with some exceptions caused mainly by extraordinary intermolecular interactions (e.g., strong acids or polar compounds like water). For this surface and therefore the relation among the three critical properties, simple relation equations, transformable and explicit in each property, were evaluated and optimized. With these equations the critical volume, pressure, or temperature can be calculated from the two remaining properties with an average absolute deviation of less than 5 % over a set of recommended critical points for 421 organic compounds. This relation is also applicable for the critical properties of binary and multicomponent mixtures. Therefore, a unique tool is ava...

The thermal behavior, upon heating, was studied for four alkanes: eicosane, tetracosane, triacontane, and tetracontane at pressures from (10 to 150) MPa. Using a transitiometer, the calorimetric signal, pressure, and temperature were measured at a very slow heating rate to guarantee thermal equilibrium. It was found that from the compounds studied, eicosane was the only one that did not present a solid–solid transition; the other compounds show a solid–solid transition a few Kelvin below the solid–liquid transition temperature. This solid–solid transition disappears when the pressure is increased in a triple point of type: solid + solid + liquid.

A static VLE apparatus has been used for the measurement of the (vapour + liquid + liquid) equilibrium of the (propylene + isopropanol + water) system at T = 313.15 K and pressures between (1.381 and 1.690) MPa. Using an isothermal flow calorimeter, H E values have been obtained for the binary system (isopropanol + water) over the temperature range from (313.15 to 353.15) K and pressures from (3.8 to 4.19) MPa. For the pseudo-binary mixture (propylene + (isopropanol + water)), H E values have been measured in the temperature range from (313.15 to 353.15) K and pressures from (1.997 to 5.89) MPa. This last mixture was studied starting from (isopropanol + water) at 0.25, 0.50, and 0.75 molar compositions in isopropanol. The new data, together with the available phase equilibrium and H E data from the literature, have been regressed by a conventional G E – EoS model reaching satisfactory results, except for the VLLE representation.

Densities, vapor pressures, and the critical point were measured for dimethyl ether, thus, filling several gaps in the thermodynamic data for this compound. Densities were measured with a computer-controlled high temperature, high-pressure vibrating-tube densimeter system in the sub- and supercritical states. The densities were measured at temperatures from 273 to 523 K and pressures up to 40 MPa (417 data points), for which densities between 62 and 745 kg/m3 were covered. The uncertainty (where the uncertainties can be considered as estimates of a combined expanded uncertainty with a coverage factor of 2) in density measurement was estimated to be no greater than 0.1% in the liquid and compressed supercritical states. Near the critical temperature and pressure, the uncertainty increases to 1%. Using a variable volume apparatus with a sapphire tube, vapor pressures and critical data were determined. Vapor pressures were measured between 264 and 194 kPa up to near the critical point with an uncertainty of 0.1 kPa. The critical point was determined visually with an uncertainty of 1% for the critical volume, 0.1 K for the critical temperature, and 5 kPa for the critical pressure. The new vapor pressures and compressed liquid densities were correlated with the simple TRIDEN model. The new data along with the available literature data were used to develop a first fundamental Helmholtz energy equation of state for dimethyl ether, valid from 131.65 to 525 K and for pressures up to 40 MPa. The uncertainty in the equation of state for density ranges from 0.1% in the liquid to 1% near the critical point. The uncertainty in calculated heat capacities is 2%, and the uncertainty in vapor pressure is 0.25% at temperatures above 200 K. Although the equation presented here is an interim equation, it represents the best currently available.

A computer-operated static apparatus has been used for the measurement of the bubble pressures of the (1,1,1,2-tetrafluoroethane + triethylene glycol dimethyl ether) system at temperatures between (283 and 323) K in the composition range where the first component is prevailing, i.e., mainly for a mole fraction in the liquid phase greater than 0.7. The chosen ranges cover the most interesting conditions for the technical applications of such a mixture in refrigeration plants. The obtained experimental data constitute a set of 125 points distributed along five isotherms. The data have been correlated using a Wilson model for the activity coefficient, reaching satisfactory results; in fact the average absolute value of the relative deviation of the experimental bubble pressure from the model is 0.16 · 10−2. At high temperatures, the mixtures with low content of triethylene glycol dimethyl ether show positive deviations from Raoult’s law, whereas the other cases are characterized by negative deviations.

Densities in the liquid phase were measured for (1,1,1,2-tetrafluoroethane + triethylene glycol dimethyl ether) using a vibrating-tube densimeter. Three mixtures with a molar fraction of refrigerant of 0.9485, 0.9655, and 0.9798 have been considered at temperatures from (283 to 323 K) at pressures up to 6 MPa. Such ranges are approximately those of interest for a compression refrigeration plant. The data at each composition were correlated with a Tait equation, and the excess volumes were also provided.

For the four aliphatic C4H8 isomers (1-butene, isobutene, cis-2-butene, and trans-2-butene), densities, vapor pressures, and critical constants were measured, thus filling several gaps in the thermodynamic data for these compounds. Densities of the four isomers were measured with a computer-controlled high temperature, high-pressure vibrating-tube densimeter system (DMA-HDT) in the subcritical and supercritical states. The densities were measured at temperatures from 273 to 523 K and pressures up to 40 MPa (1725 overall data points), for which densities between 83 and 677 kg/m3 were covered. The uncertainty in density measurement was estimated to be better than 0.1% in the liquid and compressed supercritical states. Near the critical temperature and pressure, the uncertainty increases to a maximum of 1%. Using a variable volume apparatus with a sapphire tube, vapor pressures and critical data were determined. Vapor pressures were measured from about 280 K up to near the critical point with an uncertainty of ±(0.1 kPa + 0.001P kPa and 0.07 K). The critical points were determined visually with an uncertainty of 1% for the critical volume, 0.1 K for the critical temperature, and 5 kPa for the critical pressure. The new vapor pressures and compressed liquid densities were correlated with the TRIDEN model. The new data along with other literature measurements were used to develop fundamental Helmholtz equations of state and are reported by Lemmon and Ihmels [E.W. Lemmon, E.C. Ihmels, Fluid Phase Equilib. 228–229 (2005) 173–187] in part II of this project.

Experimental measurements of density, vapor pressure, and the critical point for 1-butene, isobutene, cis -2-butene, and trans -2-butene were discussed in Part I of this work. The equations of state presented in this work were developed from these measurements and other information from the literature using a short functional form explicit in the Helmholtz energy. The functional form is based on temperature and density polynomial terms used in previous work, with both the coefficients of the equations of state and the exponents on temperature polynomial terms fitted to substance-specific data sets. Uncertainties of properties calculated using the new equations are typically 0.1% in density in the liquid phase, 0.5% in heat capacities for the saturated liquid, and 0.25–0.5% in vapor pressure. Deviations in the critical region are higher for all properties except vapor pressure. The equations are valid from the triple points of the fluids to temperatures of 525 K, with pressures to 50 MPa.

Densities of sulfur dioxide (SO 2 ) have been measured with a computer-controlled high-temperature, high-pressure vibrating-tube densimeter system (DMA-HDT) in the sub- and supercritical states. The densities were measured at temperatures from 273 to 523 K and pressures up to 35 MPa (363 overall data points), for which a density range between 194 and 1485 kg/m 3 was covered. The uncertainty in density measurement was estimated to be better than 0.1% in the liquid and compressed supercritical states. Near the critical temperature and pressure, the uncertainty increases to a maximum of 1%. Using the measured densities and additional thermodynamic data from the literature, a 12-parameter equation explicit in Helmholtz energy was developed for SO 2 . The equation of state (EoS) is valid from 197.7 to 523 K and for pressures up to 35 MPa. The uncertainty in density of the EoS ranges from 0.1% at low temperatures in the liquid and vapor to 0.5% at the highest temperatures. The uncertainty in heat capacities is 2%, and the uncertainty in vapor pressure is 0.4% at temperatures above 270 K. In the critical region, the uncertainties are higher for all properties except vapor pressure.

The group contribution method GCVOL developed by Elbro et al. (Ind. Eng. Chem. Res. 1991, 30 (12), 2576−2582) has been extended and revised. To the already existing 36 original groups 24 new groups have been introduced utilizing the Dortmund Data Bank for Pure Component Properties (DDB-Pure). With this extension now also the densities of tertiary alcohols, alkynes, carboxylic acids, allenes, cycloalkanes, fluorides, bromides, iodides, thiols, sulfides, sulfates, amines, nitriles, and nitro compounds can be calculated between the melting point and the normal boiling point. An average mean deviation of 1.5% and 1.3% for a database of 1040 compounds has been obtained for the extended GCVOL method and the newly developed method, respectively. The applicability and reliability of this group contribution method has also been compared with the corresponding state method of Rackett (J. Chem. Eng. Data 1970, 15 (4), 514−517).

Densities of γ-butyrolactone and N-methyl-2-pyrrolidone (NMP) have been measured with a com-puter-controlled high-temperature, high-pressure vibrating tube densimeter system (DMA-HDT) in the liquid state. The uncertainty in density measurement was estimated to be less than ±0.2 kg·m-3. The densities were measured for temperatures from 273 K to 473 K and pressures from 0.3 MPa up to 40 MPa, whereby a density range between (947 and 1168) kg·m-3 for γ-butyrolactone (353 data points) and between (865 and 1068) kg·m-3 for NMP (370 data points) was covered. The experimental data were correlated with the three-dimensional density correlation system (TRIDEN) and compared with published data.

Densities of five gravimetrically prepared diisopropyl ether + 1-butanol mixtures in the liquid state at different compositions have been measured with a computer-controlled high-temperature high-pressure vibrating tube densimeter system (DMA-HDT). The uncertainty in the density measurement was estimated to be lower than ±0.2 kg·m-3. The densities were measured for temperatures from 273 K to 473 K and pressures up to 35 MPa (∼320 data points for each mixture), which covered a density range between (518 and 830) kg·m-3 and an excess volume range between (−0.02 and −5) cm3·mol-1. Densities of 1-butanol were also measured in the same temperature and pressure ranges. The experimental data were correlated with the new three-dimensional density correlation system (TRIDEN); excess volumes were calculated using the densities already published for diisopropyl ether. The excess volumes and the densities of 1-butanol are compared with published data.

Densities of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and diisopropyl ether (DIPE) have been measured with a computer-controlled high-temperature, high-pressure vibrating tube densimeter system (DMA-HDT) in the liquid state. The uncertainty in the density measurement was estimated to be lower than ±0.2 kg·m-3. The densities were measured for temperatures from 273 K to 473 K and pressures up to 40 MPa for MTBE (337 data points) and for ETBE (364 data points) and up to 35 MPa for DIPE (328 data points), which covers the density range between (459 and 792) kg·m-3 for MTBE, between (494 and 792) kg·m-3 for ETBE, and between (471 and 774) kg·m-3 for DIPE. The experimental data were correlated with the new three-dimensional density correlation system (TRIDEN) and compared with published data.

Densities of sulfur hexafluoride (SF6) and dinitrogen monoxide (N2O) have been measured with a fully computer-controlled high-temperature high-pressure vibrating tube densimeter system in the sub- and supercritical states. The uncertainty in density measurement was estimated to be between ±0.2 and ±0.3 kg·m−3 depending on the temperature. With respect to accuracy, reliability, suitability, and time consumption, this system has significant advantages for measuring PρT properties in the compressed liquid and supercritical states. The densities were measured for temperatures from 273 to 623 K and at pressures up to 30 MPa for SF6 (442 data points) and from 273 to 473 K and up to 40 MPa for N2O (251 data points), which encompassed density ranges between 142.9 and 1778.5 kg·m−3 for SF6 and between 124.4 and 1051.1 kg·m−3 for N2O. Furthermore, the liquid densities of SF6 and N2O were correlated with a new three-dimensional density correlation system (TRIDEN) and the complete set of PρT data in the sub- and supercritical states were correlated with a virial-type equation of state. For checking the accuracy and suitability of the vibrating tube densimeter system, the experimental densities of SF6 were compared with published data and with the results of a reference equation of state.

Densities of toluene, carbon dioxide (CO2), carbonyl sulfide (COS), and hydrogen sulfide (H2S) have been measured with a new computer-controlled high-temperature high-pressure vibrating tube densimeter system (DMA-HDT) for temperatures from 273 K up to 623 K and pressures up to 40 MPa in the sub- and supercritical state. With respect to accuracy, reliability, suitability, and time consumption this system represents an optimum for measuring PρTproperties in the compressed liquid and supercritical state. Densities of liquid toluene, COS, and H2S as a function of temperature and pressure were correlated with the new three-dimensional density correlation system (TRIDEN). The PρT data from CO2 and the data from COS and H2S in the supercritical state and around the critical point were correlated with a virial-type equation of state. For checking the accuracy and suitability of the vibrating tube densimeter system the experimental densities of toluene and CO2 were compared with the results obtained using referen...

The thermodynamic properties of the mixture of 1,1,1,2-tetrafluoroethane (R134a) and triethylene glycol dimethyl ether (TriEGDME) have been modeled with equations of state in an extended corresponding states format. A recent equation of state for pure R134a was assumed as the reference while the scale factors have been obtained in neural network form by regression of experimental data for the mixture. The modeling was focused on the liquid phase, considering the possible application of such a mixture in a refrigeration plant; since the vapor pressure of pure TriEGDME is negligible over the considered temperature range, the vapor phase of the mixture at vapor-liquid equilibrium condition is almost pure R134a. Two fundamental equations are proposed herein. The first one, developed from a limited amount of experimental data is valid for R134a mole fractions greater than 0.94. The second equation was obtained from a wider data base; it has a larger number of free parameters to regress and covers the R134a mole fractions greater than 0.59. © 2007 American Institute of Chemical Engineers AIChE J, 2007