摘要:

The paper presents accurate representations for the thermal conductivity of the diatomic gases nitrogen and carbon monoxide in the limit of zero density. These gases were studied because they have nearly the same molecular mass and viscosities. In contrast, the new analysis confirms that the thermal conductivities of the two gases differ remarkably, especially at low temperatures. The theoretically‐based correlations provided are valid for the temperature range 220–2100 K and have associated uncertainties of ±1% between 300 and about 500 K, rising to ±2.5% at the low‐ and high‐temperature extremes. A comparison with some empirical and semiempirical correlations is given.

ISSN:0047-2689    

DOI:10.1063/1.555827

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

New correlations for the thermophysical properties of fluid methane are presented. The correlations are based on a critical evaluation of the available experimental data and have been developed to represent these data over a broad range of the state variables. Estimates for the accuracy of the equations and comparisons with measured properties are given. The reasons for this new study of methane include significant new and more accurate data, and improvements in the correlation functions which allow increased accuracy of the correlations especially in the extended critical region. For the thermodynamic properties, a classical equation for the molar Helmholtz energy, which contains terms multiplied by the exponential of the quadratic and quartic powers of the system density, is used. The resulting equation of state is accurate from about 91 to 600 K for pressures <100 MPa and was developed by consideringPVT, second virial coefficient, heat capacity, and sound speed data. Tables of coefficients and equations are presented to allow the calculation of these and other thermodynamic quantities. Ancillary equations for properties along the liquid–vapor phase boundary, which are consistent with the equation of state and lowest order scaling theory, are also given. For the viscosity of fluid methane, a low‐density contribution based on theory is combined with an empirical representation of the excess contribution. The approximate range of the resulting correlation is 91 to 400 K for pressures <55 MPa. The correlation for the thermal conductivity includes a theoretically based expression for the critical enhancement; the range for the resulting correlation is about 91 to 700 K for pressures below 100 MPa.

ISSN:0047-2689    

DOI:10.1063/1.555828

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new thermodynamic property formulation for argon is presented. The formulation includes a fundamental equation explicit in Helmholtz energy, a vapor pressure equation, and estimating functions for the densities of saturated liquid and vapor states. The coefficients of the fundamental equation and ancillary functions were determined by a weighted least‐squares fit of selected experimental data using a statistical procedure to select the terms for the equation most appropriate for the representation of the data. In determining the coefficients of the fundamental equation, multi‐property fitting methods were used to represent pressure‐density‐temperature data, saturated liquid and saturated vapor densities, and velocity of sound measurements. The fundamental equation is valid for liquid and vapor phases except near the critical point. The equation has been developed to conform to the Maxwell criterion for two‐phase liquid–vapor equilibrium states. Comparisons between the data used to determine the fundamental equation and values calculated from the formulation are given to verify the accuracy of the fundamental equation. The formulation given here may be used to calculate pressures and densities generally with an accuracy of ±0.1%, heat capacities within ±3%, and velocity of sound within ±2% except near the critical point. Tables of thermodynamic properties of argon calculated with the formulation presented here are given for fluid states within the range of validity of the correlation.

ISSN:0047-2689    

DOI:10.1063/1.555829

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Recent spectroscopic and chemical kinetic studies have provided sufficient data for construction of reliable thermodynamic tables for both dioxygen difluoride (O2F2; Chemical Abstracts Registry Number, 7783‐44‐0) and dioxygen fluoride (O2F; Chemical Abstracts Registry Number, 15499‐23‐7). This paper contains those tables for these species in both SI units (0.1 MPa standard state) and cal K mol units (1.0 atm standard state). The experimental basis includes three recent assignments of the fundamental vibrational frequencies for O2F2, a new set of rotational constants for O2F, an enthalpy change for dissociation of O2F, and an updated standard enthalpy of formation for O2F2.

ISSN:0047-2689    

DOI:10.1063/1.555830

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

This review contains recommended values of the thermodynamic and transport properties of the five and six membered ring carbohydrates and their phosphates in both the condensed and aqueous phases. Equilibrium data, enthalpies, heat capacities, and entropies have been collected from the literature. The accuracy of these data have been assessed, adjusted to 298.15 K and to a common standard state, and entered into a catalog of thermochemical reactions. The solution of this reaction catalog yields a set of recommended values for the formation properties of these substances. The volumetric data have also been critically evaluated. Recommended values are presented for standard state molar volumes and the temperature and pressure derivatives of the molar volume, i. e., the expansivity and the compressibility. The excess property data of aqueous solutions of these substances have been correlated to yield recommended values of the parameters of the virial expansion model used to represent the data. The transport data considered here includes both viscosity and diffusion data of aqueous solutions of the carbohydrates. The available phase diagram data and transition temperatures are summarized.

ISSN:0047-2689    

DOI:10.1063/1.555831

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

This paper updates and extends previous critical evaluations of the kinetics and photochemistry of gas phase chemical reactions of neutral species involved in atmosphere chemistry [J. Phys. Chem. Ref. Data9, 295 (1980);11, 327 (1982);13, 1259 (1984)]. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 360 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed; and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available data on enthalpies of formation of the reactant and product species.

ISSN:0047-2689    

DOI:10.1063/1.555832

出版商:AIP    

年代:1989

数据来源: AIP