Assessment of a Parachor Model for the Surface Tension of Binary Mixtures.

We compiled an experimental database for the surface tension of binary mixtures containing a wide variety of fluids, from the chemical classes (water, alcohols, amines, ketones, linear and branched alkanes, naphthenes, aromatics, refrigerants, and cryogens). The resulting data set includes 65 pure fluids and 154 binary pairs with a total of 8205 points. We used this database to test the performance of a parachor model for the surface tension of binary mixtures. The model uses published correlations to determine the parachors of the pure fluids. The model has a single, constant binary interaction parameter for each pair that was found by fitting experimental mixture data. It can be also used in a predictive mode when the interaction parameters are set to zero. We present detailed comparisons on the performance of the model for both cases. In general, the parachor model in a predictive mode without fitted interaction parameters can predict the surface tension of binary mixtures of non-polar mixtures such as linear and branched alkanes, linear and branched alkanes with naphthenes, aromatics with aromatics, aromatics with naphthenes, and mixtures of linear alkanes of similar sizes with an average absolute percentage deviation of about 3 % or less. Polar mixtures of halocarbons with other halocarbons and also polar/nonpolar mixtures of alkanes with halocarbons could be modeled with an average absolute deviation of less than 0.35 mN·m-1 with the use of a binary interaction parameter. The parachor model even with a fitted binary interaction parameter performs poorly for mixtures of water and organic compounds and is not recommended. Supplementary Information: The online version contains supplementary material available at 10.1007/s10765-023-03216-z.

Vapor pressure measurements on linalool using a rapid and inexpensive method suitable for cannabis-associated terpenes†.

Vapor pressure (psat) data are needed to assess the potential use of terpenes as breath markers of recent cannabis use. Herein, a recently introduced gas-saturation method for psat measurements, known as dynamic vapor microextraction (DVME), was used to measure psat for the terpene (±)-3,7-dimethylocta-1,6-dien-3-ol, commonly known as linalool. The DVME apparatus utilizes inexpensive and commercially available components, a low internal volume, and helium carrier gas to minimize nonideal mixture behavior. In the temperature range from 314 K to 354 K, DVME-based measurements of the psat of linalool ranged from 81 Pa to 1250 Pa. With a measurement period of 30 min, the combined standard uncertainty of these measurements ranged from 0.0358·psat to 0.0584·psat, depending on temperature. The DVME-based measurements agree with a Wagner correlation of available literature data. We demonstrate that DVME produces accurate results for values of psat that are 200 times higher than in the DVME validation study with n-eicosane (C20H42). The oxidative stability of linalool was improved by the addition of 0.2 mass % of the antioxidant tert-butylhydroquinone.

The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.

The NIST REFPROP software program is a powerful tool for calculating thermophysical properties of industrially important fluids, and this manuscript describes the models implemented in, and features of, this software. REFPROP implements the most accurate models available for selected pure fluids and their mixtures that are valid over the entire fluid range including gas, liquid, and supercritical states, with the goal of uncertainties approaching the level of the underlying experimental data. The equations of state for thermodynamic properties are primarily of the Helmholtz energy form; a variety of models are implemented for the transport properties. We document the models for the 147 fluids included in the current version. A graphical user interface generates tables and provides extensive plotting capabilities. Properties can also be accessed through third-party apps or user-written code via the core property subroutines compiled into a shared library. REFPROP disseminates international standards in both the natural gas and refrigeration industries, as well as standards for water/steam.

Thermal Conductivity of Binary Mixtures of 1,1,1,2-Tetrafluoroethane(R-134a), 2,3,3,3-Tetrafluoropropene (R-1234yf), and trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E)) Refrigerants.

A total of 2160 thermal conductivity data points, measured using a transient hot-wire instrument, are reported for binary mixtures of R-134a, R-1234yf, and R-1234ze(E) refrigerants from 200 to 340 K to pressures of 12 MPa for mixtures containing R-1234yf and to 50 MPa for R-134a/1234ze(E) mixtures. Data are reported at compositions of approximately (0.33/0.67) mole fraction and (0.67/0.33) mole fraction for each binary mixture investigated. The estimated relative expanded uncertainty of the thermal conductivity measurements is less than 2%. The data are used to refit binary interaction parameters for the Extended Corresponding States (ECS) model implemented in REFPROP (version 10.0). Additionally, the data in this study are used to assess the performance of a generalized entropy scaling model for refrigerants. Finally, the strengths and weaknesses of the ECS and entropy scaling models are compared.

Reference Correlation for the Viscosity of Xenon from the Triple Point to 750 K and up to 86 MPa.

A new wide-ranging correlation for the viscosity of xenon, based on the most recent theoretical calculations and critically evaluated experimental data, is presented. The correlation is designed to be used with an existing equation of state, and it is valid from the triple point to 750 K, at pressures up to 86 MPa. The estimated expanded uncertainty (at a coverage factor of k = 2) varies depending on the temperature and pressure, from 0.2 % to 3.6 %. A term accounting for the critical enhancement is also included. The correlation behaves in a physically reasonable manner when extrapolated to 200 MPa, however care should be taken when using the correlations outside of the validated range.

Reference Correlation for the Thermal Conductivity of Ethane-1,2-diol (Ethylene Glycol) from the Triple Point to 475 K and Pressures up to 100 MPa.

We present a new wide-ranging correlation for the thermal conductivity of ethane-1,2-diol (ethylene glycol) based on critically evaluated experimental data. The correlation is designed to be used with an existing equation of state, and it is valid from the triple point to 475 K, at pressures up to 100 MPa. The estimated uncertainty is 2.2 % (at the 95 % confidence level), except in the dilute-gas region which is estimated to be 20 %, as there are no measurements in this region for comparison.

Reference Correlation for the Viscosity of Ethane-1,2-diol (Ethylene Glycol) from the Triple Point to 465 K and up to 100 MPa.

We present a new wide-ranging correlation for the viscosity of ethane-1,2-diol (ethylene glycol) based on critically evaluated experimental data. The correlation is designed to be used with an existing equation of state, and it is valid from the triple point to 465 K, at pressures up to 100 MPa. The estimated uncertainty is 4.9 % (at the 95 % confidence level), except in the dilute-gas region which is estimated to be 15 %, as there are no measurements in this region for comparison. The correlation behaves in a physically reasonable manner when extrapolated to 750 K and 250 MPa, however care should be taken when using the correlations outside of the validated range.

Measurement and Correlation of the Thermal Conductivity of cis-1,1,1,4,4,4-hexafluoro-2-butene.

New experimental data for the thermal conductivity of cis-1,1,1,4,4,4-hexafluoro-2-butene (R-1336mzz(Z)) are reported for vapor, liquid and supercritical states. These data were obtained with transient hot-wire apparatus over the temperature range from 192 K to 498 K and at pressures from 0.05 MPa to 69 MPa. These data were used to develop a wide-range correlation for the thermal conductivity of the vapor, liquid, and supercritical fluid. The experimental data reported here have an uncertainty of 1 % for the liquid and supercritical regions (densities above 600 kg·m-3), 1.5 % for vapor and supercritical regions (pressures greater than or equal to 1 MPa and densities less than 200 kg·m-3), 3 % for supercritical states (densities between 200 kg·m-3 and 600 kg·m-3), and 3 % for vapor and supercritical states (pressures below 1 MPa). The thermal-conductivity correlation developed in this work is estimated to have an expanded relative uncertainty, at a 95 % confidence level, ranging from approximately 1.4 % to 4.2 % depending on the temperature and pressure, with larger uncertainties in the critical region.

(R)Evolution of Refrigerants.

As we enter the "fourth generation" of refrigerants, we consider the evolution of refrigerant molecules, the ever-changing constraints and regulations that have driven the need to consider new molecules, and the advancements in the tools and property models used to identify new molecules and design equipment using them. These separate aspects are intimately intertwined and have been in more-or-less continuous development since the earliest days of mechanical refrigeration, even if sometimes out-of-sight of the mainstream refrigeration industry. We highlight three separate, comprehensive searches for new refrigerants-in the 1920s, the 1980s, and the 2010s-that sometimes identified new molecules, but more often, validated alternatives already under consideration. A recurrent theme is that there is little that is truly new. Most of the "new" refrigerants, from R-12 in the 1930s to R-1234yf in the early 2000s, were reported in the chemical literature decades before they were considered as refrigerants. The search for new refrigerants continued through the 1990s even as the hydrofluorocarbons (HFCs) were becoming the dominant refrigerants in commercial use. This included a return to several long-known natural refrigerants. Finally, we review the evolution of the NIST REFPROP database for the calculation of refrigerant properties.

A Distillation Approach to Phase Equilibrium Measurements of Multicomponent Fluid Mixtures.

By building on the Advanced Distillation Curve (ADC) approach to measuring the volatility of fuels and other fluid mixtures, the ADC with Reflux or ADCR technique was developed to address the difficulty of experimentally determining the vapor-liquid equilibrium of fluids containing many components. For fuels and other multicomponent mixtures, the ADCR collects data about the chemical compositions of both liquid and vapor phases across a range of temperatures, elucidating the two-phase region at constant pressure. Two simple mixtures were used to demonstrate the ADCR method: an n-decane/n-tetradecane binary and the Huber-Bruno surrogate, a ternary mixture designed to represent the volatility of an aviation turbine kerosene. These mixtures were chosen to test the method because they have been extensively studied and modeled in previous work. For both test fluids, the ADCR measurements of vapor-liquid equilibrium were in good agreement with model predictions. We conclude that the ADCR is a useful method for determining the T-P-x-y behavior of fluid mixtures with many components. The experimental approach presented may support the development of fuels, design of separations, and forensic sciences that use vapor analysis, especially arson fire debris analysis, by providing quantitative data with well-characterized uncertainty describing the relationships between the vapor and condensed phases of a fuel subjected to thermal weathering.

Measurement and Correlation of the Thermal Conductivity of 1,1,1,2,2,4,5,5,5-Nonafluoro-4-(trifluoromethyl)-3-pentanone.

New experimental data for the thermal conductivity of 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (Novec 649) are reported for vapor, liquid and supercritical states. These new experimental data were obtained with transient hot-wire apparatus over the temperature range from 183 K to 501 K and at pressures from 0.02 MPa to 69 MPa. These data were used to develop a wide-range correlation for the thermal conductivity of the vapor, liquid and supercritical fluid. The experimental data reported here have an uncertainty of 1 % for the liquid and supercritical regions (densities > 600 kg m-3), 1.5 % for vapor and supercritical regions (pressures ≥ 1 MPa and densities < 200 kg m-3), 3 % for supercritical states (200 kg m-3 ≤ densities ≤ 600 kg m-3), and 3 % for vapor and supercritical states (pressures < 1 MPa). The thermal-conductivity correlation developed in this work is estimated to have an expanded relative uncertainty, at a 95 % confidence level, ranging from approximately 1 % to 4 % that depends upon the temperature and pressure, with larger uncertainties in the critical region.

Measurement and Correlation of the Thermal Conductivity of trans-1-Chloro-3,3,3-trifluoropropene (R1233zd(E)).

New experimental data on the thermal conductivity of trans-1-chloro-3,3,3-trifluoropropene (R1233zd(E)) are reported that allow the development of wide-range correlations. These new experimental data, covering a temperature range of 204 K to 453 K at pressures from 0.1 MPa to 67 MPa, are used to develop a correlation for the thermal conductivity. The experimental data reported here have an uncertainty of (1 - 1.5) % for liquid measurements and for gas at pressures above 1 MPa, increasing to (3 - 4) % for gas at low pressures (less than 1 MPa) and near the gas-liquid critical point. Based on the uncertainty of and comparisons with the present data, the thermal-conductivity correlation for R1233zd(E) is estimated to have a relative expanded uncertainty ranging at a 95 % confidence level from 1 % to 4 % depending on the temperature and pressure, with larger uncertainties in the critical region.

Measurement and Correlation of the Viscosity of 1,1,1,2,2,4,5,5,5-Nonafluoro-4-(trifluoromethyl)-3-pentanone.

The Paris Agreement on climate change, in which many nations have agreed to limit greenhouse gas emissions, has spurred interest in developing working fluids with low global warming potential (GWP) that can satisfy environmental concerns and have thermophysical properties that can meet engineering performance requirements. One such fluid is 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (also known as Novec-649 and Novec-1230), which has potential applications in organic Rankine cycles (ORC), electronics cooling, computer/data center cooling and fire extinguishing. In this work, viscosity measurements of 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone were reported. The measurements were performed over the temperature range of (243 to 373) K and at pressures up to 40 MPa using a vibrating-wire viscometer. The combined expanded uncertainty of the reported viscosity was 2 % with a confidence level of 0.95 (k = 2). These experimental data were used to develop a viscosity correlation that covers a wide temperature and pressure range, with an estimated uncertainty at a 95% confidence level of 2% for the liquid phase from (240 to 400) K at pressures up to 40 MPa.

Reference correlations for the thermal conductivity of liquid copper, gallium, indium, iron, lead, nickel and tin.

The available experimental data for the thermal conductivity of liquid copper, gallium, indium, iron, lead, nickel, and tin has been critically examined with the intention of establishing thermal conductivity reference correlations. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the thermal conductivity of liquid copper, gallium, indium, iron, lead, nickel, and tin are respectively characterized by uncertainties of 9.8, 15.9, 9.7, 13.7, 16.9, 7.7, and 12.6% at the 95% confidence level.

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 manuscript 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.

Diesel Surrogate Fuels for Engine Testing and Chemical-Kinetic Modeling: Compositions and Properties.

The primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e., increasing exactness in matching hydrocarbon structural characteristics) relative to the single target diesel fuel upon which the surrogate fuels are based. This approach was taken to assist in determining the minimum level of surrogate-fuel compositional accuracy that is required to adequately emulate the performance characteristics of the target fuel under different combustion modes. For each of the four surrogate fuels, an approximately 30 L batch was blended, and a number of the physical and chemical properties were measured. This work documents the surrogate-fuel creation process and the results of the property measurements.

Prediction and preliminary standardization of fire debris constituents with the advanced distillation curve method.

The recent National Academy of Sciences report on forensic sciences states that the study of fire patterns and debris in arson fires is in need of additional work and eventual standardization. We discuss a recently introduced method that can provide predicted evaporation patterns for ignitable liquids as a function of temperature. The method is a complex fluid analysis protocol, the advanced distillation curve approach, featuring a composition explicit data channel for each distillate fraction (for qualitative, quantitative, and trace analysis), low uncertainty temperature measurements that are thermodynamic state points that can be modeled with an equation of state, consistency with a century of historical data, and an assessment of the energy content of each distillate fraction. We discuss the application of the method to kerosenes and gasolines and outline how expansion of the scope of fluids to other ignitable liquids can benefit the criminalist in the analysis of fire debris for arson.

The composition-explicit distillation curve technique: Relating chemical analysis and physical properties of complex fluids.

The analysis of complex fluids such as crude oils, fuels, vegetable oils and mixed waste streams poses significant challenges arising primarily from the multiplicity of components, the different properties of the components (polarity, polarizability, etc.) and matrix properties. We have recently introduced an analytical strategy that simplifies many of these analyses, and provides the added potential of linking compositional information with physical property information. This aspect can be used to facilitate equation of state development for the complex fluids. In addition to chemical characterization, the approach provides the ability to calculate thermodynamic properties for such complex heterogeneous streams. The technique is based on the advanced distillation curve (ADC) metrology, which separates a complex fluid by distillation into fractions that are sampled, and for which thermodynamically consistent temperatures are measured at atmospheric pressure. The collected sample fractions can be analyzed by any method that is appropriate. The analytical methods we have applied include gas chromatography (with flame ionization, mass spectrometric and sulfur chemiluminescence detection), thin layer chromatography, FTIR, corrosivity analysis, neutron activation analysis and cold neutron prompt gamma activation analysis. By far, the most widely used analytical technique we have used with the ADC is gas chromatography. This has enabled us to study finished fuels (gasoline, diesel fuels, aviation fuels, rocket propellants), crude oils (including a crude oil made from swine manure) and waste oils streams (used automotive and transformer oils). In this special issue of the Journal of Chromatography, specifically dedicated to extraction technologies, we describe the essential features of the advanced distillation curve metrology as an analytical strategy for complex fluids.

Revised Standardized Equation for Hydrogen Gas Densities for Fuel Consumption Applications.

An equation for the density of hydrogen gas has been developed that agrees with the current standard to within 0.01 % from 220 K to 1000 K with pressures up to 70 MPa, to within 0.01 % from 255 K to 1000 K with pressures to 120 MPa, and to within 0.1 % from 200 K to 1000 K up to 200 MPa. The equation is a truncated virial-type equation based on pressure and temperature dependent terms. The density uncertainty for this equation is the same as the current standard and is estimated to be 0.04 % (combined uncertainty with a coverage factor of 2) between 250 K and 450 K for all pressures, and 0.1 % for lower temperatures. Comparisons are presented with experimental data and with the full equation of state.