Pure vapor viscosity

For prediction of the vapor viscosity of pure hydrocarbons at low pressure (below Tr of 0., the method of Stiel and Thodos is the most accurate. Only the molecular weight, the critical temperature, and the critical pressure are required. Equation (2-97) with values of N from Eqs. (2-98) and (2-99) is used. 

For nonpolar, nonhydrocarbon vapor mixtures at high pressures, the method of Dean and Stiel [Eq- (2-102)] discussed earlier can be used. The accuracy of the method is excellent and dependent on the pure component viscosity values used as input parameters. 

The vapor viscosity, thermal conductivity, and pure component capacities have been taken from the detailed calculations of Austin and Jeffreys (1979). For the purpose of this particular example these properties are assumed to be independent of temperature and composition. This may not be a particularly good assumption in this case since the temperature and composition changes are relatively large and the properties of the pure components also differ quite widely. 

Example 13-3 To demonstrate the use of the predictive method, Example 13-3, which is taken from Ref. 24, is presented. A statement of this example appears in Table 13-4. Physical properties which are listed in the table were estimated as follows. The viscosity of each pure component i in the vapor phase was predicted by use of the correlation proposed by Bird et al.1,2 20 The pure component viscosities so obtained were used to predict the viscosities of the vapor mixtures by use of the semi-empirical formula proposed by Wilke.40... 

If critical pressure and critical temperature are given in Pa and K, respectively, viscosities in centipoise result. The variable Io is either the low pressure pure component or mixture viscosity according to whether a pure component or mixture is being considered. For mixtures, simple molar average pseiidocritical temperature (Kay s rule), pressure, and density, and molar average molecular weight are used. The vapor density can be predicted by the methods previously discussed. Errors of above 5 percent are common for hydrocarbons and their mixtures. Experimental densities will reduce the errors slightly. 

Of course, a primary concern for any physical property measurement, including gas solubility, is the purity of the sample. Since impurities in ILs have been shown to affect pure component properties such as viscosity [10], one would anticipate that impurities might affect gas solubilities as well, at least to some extent. Since ILs are hygroscopic, a common impurity is water. There might also be residual impurities, such as chloride, present from the synthesis procedure. Surprisingly though, we found that even as much as 1400 ppm residual chloride in l-n-octyl-3-methylimi-dazolium hexafluorophosphate and tetrafluoroborate ([OMIM][PFg] and [OMIM] [BF4]) did not appear to have any detectable effect on water vapor solubility [1]. 

White metal with brdhant metaUic luster face-centered cubic crystals density 10.43 g/cm at 20°C, and 9.18 g/cm at 1,100°C melts at 961.8°C vaporizes at 2,162°C vapor pressure 5 torr at 1,500° C pure metal has the highest electrical and thermal conductive of aU metals, electrical resistivity of pure metal at 25°C 1.617x10 ohm-cm elastic modulus 71GPa (10.3x10 psi) Poisson s ratio 0.39 (hard drawn), 0.37 (annealed) viscosity of hquid silver 3.97 centipoise at 1,043°C thermal neutron absorption cross section 63 1 barns insoluble in water inert to most acids attacked by dilute HNO3 and concentrated H2SO4 soluble in fused caustic soda or caustic potash in the presence of air. 

For any pure chemical species, there exists a critical temperature (Tc) and pressure (Pc) immediately below which an equilibrium exists between the liquid and vapor phases (1). Above these critical points a two-phase system coalesces into a single phase referred to as a supercritical fluid. Supercritical fluids have received a great deal of attention in a number of important scientific fields. Interest is primarily a result of the ease with which the chemical potential of a supercritical fluid can be varied simply by adjustment of the system pressure. That is, one can cover an enormous range of, for example, diffusivities, viscosities, and dielectric constants while maintaining simultaneously the inherent chemical structure of the solvent (1-6). As a consequence of their unique solvating character, supercritical fluids have been used extensively for extractions, chromatographic separations, chemical reaction processes, and enhanced oil recovery (2-6). 

The table below provides data on the most important properties of pure water under different temperatures. These properties are density (g/ml), molar volume (ml/mol), vapor pressure (in kPa and mmHg), static dielectric constant, and dynamic viscosity (mPa sec). The properties other than the vapor pressure are evaluated at a pressure of 101.325 kPa or the vapor pressure, whichever is higher. 

The physical property monitors of ASPEN provide very complete flexibility in computing physical properties. Quite often a user may need to compute a property in one area of a process with high accuracy, which is expensive in computer time, and then compromise the accuracy in another area, in order to save computer time. In ASPEN, the user can do this by specifying the method or "property route", as it is called. The property route is the detailed specification of how to calculate one of the ten major properties for a given vapor, liquid, or solid phase of a pure component or mixture. Properties that can be calculated are enthalpy, entropy, free energy, molar volume, equilibrium ratio, fugacity coefficient, viscosity, thermal conductivity, diffusion coefficient, and thermal conductivity. 

There have been three experimental investigations of the viscosity of liquid hydrogen sulfide. The three studies are summarized in table 2A.1. For the two low-temperature studies, Steele et al. (1906) and Runovskaya et al. (1970), the pressure was probably 1 atm (101.325 kPa), whereas the study of Hennel and Krynicki (1959) was at the vapor pressure of pure H2S. 

Properties Colorless liquid aromatic odor. Vapor heavier than air, bp 136.187C, refr index 1.49594 (20C), d 0.867 (20C), fp -95C, bulk d 7.21 lb/gal (25C), flash p 59F (15C), autoign temp 810F (432C), specific heat 0.41 cal/gal/K, viscosity 0.64 cP (25C). Soluble in alcohol, benzene, carbon tetrachloride, and ether almost insoluble in water. Derivation (1) By heating benzene and ethylene in the presence of aluminum chloride, with subsequent distillation (2) by fractionation directly from the mixed xylene stream in petroleum refining. Grade Technical, pure, research. 

Mass density (p), viscosity (rj), refractive index at a wavelength of 589 nm (raD), relative dielectric constant (e), vapor pressure (pv), and surface tension (y) of pure water at various temperatures (I). 

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