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We present a new wide-ranging correlation for the viscosity of 1,1,1,2-tetrafluoroethane (R-134a) based on critically evaluated experimental data. The correlation is designed to be used with densities from an existing equation of state, which is valid from the triple point to 438 K, at pressures up to 70 MPa. The estimated uncertainty (at the 95 % confidence level) for the viscosity varies depending on the temperature and pressure, from a low of 0.2 % in the dilute-gas range near room temperature, to 2 % along the saturated vapor boundary, 2.5 % for the saturated liquid, and 4 % for some high-pressure regions. The correlation behaves in a physically reasonable manner when extrapolated to pressures above 70 MPa. Comparisons with experimental data at pressures to 400 MPa are given. However, care should be taken when using the correlation outside of the validated range of the equation of state. [ABSTRACT FROM AUTHOR]

In this study, we have examined the modeling of gas solubility in twenty room temperature ionic liquids based on the van der Waals and generic Redlich–Kwong equations of state and have also compared the obtained deviations with each other. The selected gases are carbon dioxide (R744) and 1,1,1,2-tetrafluoroethane (R134a). Experimental data represent a high correlation with the present equations of state. It is concluded that the absolute average deviation is less than 1% for each system, which illustrates the high accuracy and efficiency of the mentioned equations of state. Henry's law constant and some thermodynamic properties such as enthalpy and entropy in infinite dilution are calculated. [ABSTRACT FROM AUTHOR]

The reaction of 1,1,1,2-tetrafluoroethane with fluorine in a gas-liquid reactor with a high-speed stirrer and with perfluorodecalin or perfluoro-1,3-dimethylcyclohexane as a liquid phase occurs as hydrogen substitution without noticeable cleavage of C-C bonds, yielding penta- and hexafluoroethane. The fluorination of methane in perfluorodecalin under the same conditions yields, depending on the methane and fluorine concentrations in their mixtures with an inert gas, products of successive hydrogen substitution by fluorine when the reaction occurs in approximately isothermal mode and products corresponding to the thermodynamic equilibrium when the reaction occurs in the mode of gas-phase diffusion combustion on the gas bubble scale. [ABSTRACT FROM AUTHOR]

The porous alumina catalysts with different acidity were prepared and tested for dehydrofluorination of 1,1,1,2-tetrafluoroethane to synthesize trifluoroethylene. The XRD, BET, SEM, NH-TPD and py-IR techniques were used to characterize the alumina catalysts with different calcination temperatures. The porous θ-AlO showed the excellent catalytic performance, with 35.1 % conversion and the selectivity to trifluoroethylene of 99.0 %. The active sites of catalysts for formation of trifluoroethylene are appropriate weak Lewis acid sites, and the strong Lewis acid sites may result in its rapid deactivation, due to the coke or polymerization of trifluoroethylene. Graphical Abstract: Dehydrofluorination of 1,1,1,2-tetrafluoroethane (CFCFH) is a promising route to synthesize trifluoroethylene over θ-AlO, the conversion is 35.1 % and the selectivity to trifluoroethylene is 99 % at 450 °C. It was suggested that appropriate number of weak Lewis acid sites was beneficial to the catalysis for dehydrofluorination of CFCFH, the weak Lewis acid sites as the active sites of synthesis of trifluoroethylene. On the other hand, the strong Lewis acid sites easily result in deactivation of catalysts derived from the coke or polymerization of trifluoroethylene.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The performance of 1,1,1,2-tetrafluoroethane or HFC-134a decomposition and the formation of byproducts in a dielectric barrier discharge plasma reactor were studied with different packing systems such as α-AlO (porous and nonporous), γ-AlO (porous) and ZrO (nonporous). Experimental variables such as reactor temperature, initial HFC-134a concentration and oxygen levels were chosen for the performance analysis. Among the packing systems, the porous γ-AlO and α-AlO decomposed HFC-134a much more effectively than the nonporous α-AlO and ZrO. The combination of the plasma with the porous γ-AlO was found to cover a wide range of initial concentration. The decomposition efficiency tended to increase with the addition of oxygen up to 2 %, but further increase in the oxygen led to a decrease. As well as carbon oxides (CO and CO), significant amounts of unwanted byproducts such as COF and CF were also identified in the effluent gas with the nonporous α-AlO and ZrO. On the contrary, with the porous γ-AlO and α-AlO, such unwanted byproducts were considerably suppressed, enhancing the formation of CO and CO. [ABSTRACT FROM AUTHOR]

In this study, experimental and simulation studies of the evaporation heat transfer coefficient and pressure drop of R-134a flowing through corrugated tubes are conducted. The test section is a horizontal counter-flow concentric tube-in-tube heat exchanger 2.0 m in length. A smooth tube and corrugated tubes with inner diameters of 8.7 mm are used as the inner tube. The outer tube is made from a smooth copper tube with an inner diameter of 21.2 mm. The corrugation pitches used in this study are 5.08, 6.35, and 8.46 mm. Similarly, the corrugation depths are 1, 1.25, and 1.5 mm, respectively. The results show that the maximum heat transfer coefficient and pressure drop obtained from the corrugated tube are up to 22 and 19 % higher than those obtained from the smooth tube, respectively. In addition, the average difference of the heat transfer coefficient and pressure drop between the simulation model and experimental data are about 10 and 15 %, respectively. [ABSTRACT FROM AUTHOR]

Viscosity measurements have been carried out with a falling-cylinder instrument in the compressed liquid and supercritical regions of the hydrofluorocarbon 1,1,1,2-tetrafluoroethane (R134a). A highly pure sample was used. The measurement region at temperatures from 293.15 K to 438.15 K with pressures from 10 MPa to 400 MPa extends the existing data range substantially. With estimated uncertainties of 3.5 % for viscosity, the greater of 1 MPa or 0.5 % for pressure, and 0.4 K for temperature, the new results can be used to reconcile inconsistencies between literature data sets. They also provide a test of the extrapolation capability of existing viscosity correlations for this fluid and enable the development of a more accurate and wider ranging formulation. [ABSTRACT FROM AUTHOR]

Using a pulsed Townsend technique, we have measured the drift velocity, the longitudinal diffusion coefficient and the effective ionisation coefficient of electrons in R134a and R134a-Ar over a wide range of the density-reduced electric field intensity, E/N. Regarding the measurement of the electron drift velocities and of the effective ionization coefficients, we have covered a wider range than that hitherto achieved for pure R134a. Both the electron drift velocity and the effective ionisation coefficient have been found in very good agreement with those published in the literature, covering a shorter range of E/N. On the other hand, the swarm coefficients on R134a-Ar are, to the best of our knowledge, the first to be published. It is hoped that these data will be of interest for the test/derivation of electron collision cross sections for this important hydrofluorocarbon gas, which is nowadays of great use in gaseous detectors. [ABSTRACT FROM AUTHOR]

Nonideal association in the vapor phase of HF poses a challenge in modeling. In this paper, a hybrid HF equation in the ASPEN Plus process simulation software and an equation of Anderko and co-workers are compared. Lencka and Anderko used a general framework to combine a simple association model with a cubic equation. This formulation helps to represent the phase behaviors of HF and halocarbon mixtures, especially for systems containing two liquid phases. [ABSTRACT FROM AUTHOR]

The p– ρ– T relationships and constant volume heat capacity Cv were measured for ternary refrigerant mixtures by isochoric methods with gravimetric determinations of the amount of substance. Temperatures ranged from 200 to 400 K for p– ρ– T and from 203 to 345 K for Cv, while for both data types pressures extended to 35 MPa. Measurements of p– ρ– T were carried out on compressed gas and liquid samples with the following mole fraction compositions: 0.3337 R32+0.3333 R125+0.3330 R134a and 0.3808 R32+0.1798 R125+0.4394 R134a. Measurements of Cv were carried out on liquid samples for the same two compositions. Published p– ρ– T data are in good agreement with this study. For the p– ρ– T apparatus, the uncertainty is 0.03 K for temperature and is 0.01% for pressure at p>3 MPa and 0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (∼28.5 cm3), with a standard uncertainty of 0.003 cm3. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and, thus, a two-standard deviation estimate) of the density measurements is estimated to be 0.05%. For the Cv calorimeter, the uncertainty of the temperature rise is 0.002 K and for the change-of-volume work it is 0.2%; the latter is the principal source of uncertainty. When all components of experimental uncertainty are considered, the expanded relative uncertainty of the heat capacity measurements is estimated to be 0.7%. [ABSTRACT FROM AUTHOR]

The p– ρ– T relationships were measured for binary refrigerant mixtures by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 200 to 400 K, while pressures extended up to 35 MPa. Measurements were conducted on compressed gas and liquid samples with the following mole fraction compositions: 0.4997 R32+0.5003 R134a, 0.3288 R32+0.6712 R134a, 0.4996 R32+0.5004 R125, 0.5001 R125+0.4999 R134a, and 0.5000 R125+0.5000 R143a. Most published p– ρ– T data are in good agreement with this study. The uncertainty is 0.03 K for temperature and is 0.01% for pressure at p>3 MPa and 0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (∼28.5 cm3), with a standard uncertainty of 0.003 cm3. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and, thus, a two-standard deviation estimate) of the density measurements is estimated to be 0.05%. [ABSTRACT FROM AUTHOR]

Molar heat capacities at constant volume Cv were measured for binary refrigerant mixtures with an adiabatic calorimeter with gravimetric determinations of the amount of substance. Temperatures ranged from 200 to 345 K, while pressures extended up to 35 MPa. Measurements were conducted on liquid samples with equimolar compositions for the following binary systems: R32/R134a, R32/R125, R125/R134a, and R125/R143a. The uncertainty is 0.002 K for the temperature rise and is 0.2% for the change-of-volume work, which is the principal source of uncertainty. The expanded relative uncertainty (with a coverage factor k=2 and thus a two-standard deviation estimate) for Cv is estimated to be 0.7%. [ABSTRACT FROM AUTHOR]

This paper reports the results of an international project coordinated by the Subcommittee on Transport Properties of Commission I.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a and culminates the effort which was initially described in 1995. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the samples. This paper provides an intercomparison of the new experimental results obtained for the viscosity and thermal conductivity in the vapor, liquid, and supercritical gas phases. The viscosity measurements were made with a variety of techniques including the vibrating wire, oscillating disk, capillary flow, and falling body. Thermal conductivity was measured using transient bare and anodized hot wires, steady-state anodized hot wires, and light scattering. Agreement between a variety of experimental techniques using the standard round-robin sample is necessary to demonstrate that some of the discrepancies in earlier results were due to sample impurities. Identification of disagreement between data using one experimental technique relative to other techniques may suggest modifications that would lead to more accurate measurements on these highly polar refrigerant materials. It is anticipated that the new data which have been measured on this IUPAC round-robin sample will aid in the identification of the reliable data sets in the literature and ultimately allow the refinement of the IUPAC reference-data correlations for the transport properties of R134a. [ABSTRACT FROM AUTHOR]

Catalytic fluorination of HCFC-133a was performed over metal oxide catalysts. Chromium oxide showed the best catalytic activity among several metal oxides tested. An increase in the crystallinity with decreased surface area resulted in a decrease of catalytic activity for the fluorination reaction. Active phase of chromia is Cr-O-F-OH having a proper ratio of O/F and a high hydroxyl content. The hydroxyl content on the catalyst is strongly dependent on support material. The selectivity to HFC-134a is independent of the O/F ratio on the Cr surface. [ABSTRACT FROM AUTHOR]

The thermal conductivity of HFC 134a was measured in the liquid phase with the polarized transient hot-wire technique. The experiments were performed at temperatures from 213 to 293 K at pressures up to 20 MPa. The data were analyzed to obtain correlations in terms of density and pressure. This study is part of an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of IUPAC, conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of HFC 134a, using samples of different origin. Two samples of HFC 134a from different sources have been used. The thermal conductivity of the first sample was measured along the saturation line as a function of temperature and the data were presented earlier. The thermal conductivity of the second one, the round-robin sample was measured as a function of pressure and temperature. These data were extrapolated to the saturation line and compared with the data obtained, previously in order to demonstrate the importance of the sample origin and their real purity. The accuracy of the measurements is estimated to be 0.5%. Finally, the results are compared with the existing literature data. [ABSTRACT FROM AUTHOR]

Vapor pressures were evaluated from measured internal-energy changes in the vapor+liquid two-phase region, Δ U (2). The method employed a thermodynamic relationship between the derivative quantity (ϖ U (2)/ϖ V) T and the vapor pressure ( p σ) and its temperature derivative (ϖ p/ϖ T)σ. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), and difluoromethane (R32). Agreement with experimentally measured vapor pressures near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately ±0.04 kPa (±0.04%). The method was applied to R134a to test the thermodynamic consistency of a published p-p-T equation of state with an equation for p σ for this substance. It was also applied to evaluate published p σ data which are in disagreement by more than their claimed uncertainty. [ABSTRACT FROM AUTHOR]