摘要:

Perfluoroethane (C2F6,hexafluoroethane) is a man-made gas with many important applications (e.g., in the aluminum industry, the semiconductor industry, plasma chemistry and etching technologies, and pulsed power switching). In these and other uses, knowledge of the interactions of slow electrons (kinetic energies less than about 100 eV) is fundamental in optimizing performance parameters involved in the particular application. We, therefore, have critically evaluated and synthesized existing knowledge on electron interactions withC2F6.The following cross sections and their intercomparison are presented and discussed: total electron scattering, momentum transfer, integral elastic, differential elastic, differential vibrational, vibrational inelastic, total ionization, partial ionization, total dissociation, and electron attachment. Information is presented also on the coefficients for electron impact ionization, effective ionization, electron attachment, and electron transport (lateral diffusion coefficient and drift velocity), as well as on the rate constant for electron attachment as a function of the mean electron energy and gas temperature. While some information is available for these cross sections, additional measurements are needed for each of them, especially for inelastic electron scattering and momentum transfer. No published data are available for dissociation ofC2F6into neutral fragments. The coefficients are generally better known than the cross sections although further measurements on electron diffusion coefficients and electron attachment at highE/Nvalues are indicated. ©1998 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556016

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

When representative equations for the viscosity of carbon dioxide were published in 1990, it was recognized that, owing to inconsistencies among the available experimental liquid viscosity data which could not be resolved, new measurements were necessary. Since then, two new sets of measurements have been performed and it is appropriate to revise the published equations in order to improve their performance in the liquid region. In the previous work, the excess viscosity was represented by two separate equations, one for the gas phase and the other, a provisional one, for the liquid phase. Both equations were joined by a blending function. In the present work, the excess viscosity for the whole thermodynamic surface is represented by one equation. The resulting overall viscosity representation for carbon dioxide covers the temperature range 200 K⩽T⩽1500 K and densities up to 1400kg m−3. In terms of pressure, the viscosity representation is valid up to 300 MPa for temperatures below 1000 K, whereas for higher temperatures and owing to the limitation of the equation of state used, the upper pressure limit is restricted to 30 MPa. The uncertainties associated with the proposed representation vary from±0.3&percent; for the viscosity of the dilute gas near room temperature to±5.0&percent; at the highest pressures. Tables of viscosity generated by the representative equations are included for easy reference and to assist validation of computer coding. ©1998 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556013

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Mixtures of water and ammonia play an important role in absorption refrigeration cycles and have received attention as working fluids in modern power generation cycles. For design and simulations during the development of any application, the thermodynamic properties have to be known accurately. Measurements of available thermodynamic data are compiled and summarized. The data sets are compared, using a Helmholtz free energy formulation. Recommendations are given for which data sets are suited to serve as a basis for an equation of state formulation of the thermodynamic properties of{water+ammonia}.Gaps in the database are shown to give experimenters orientation for future research. ©1998 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556014

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A thermodynamic model incorporating a fundamental equation of state for the Helmholtz free energy of the mixture {water+ammonia} is presented which covers the thermodynamic space between the solid–liquid–vapor boundary and the critical locus. It is also valid in the vapor and liquid phases for pressures up to 40 MPa. It represents vapor–liquid equilibrium properties with an uncertainty of±0.01 in liquid and vapor mole fractions. Typical uncertainties in the single-phase regions are±0.3&percent; for the density and ±200J mol−1for enthalpies. Details of the data selection and the optimization process are given. The behavior of the fundamental equation of state is discussed in all parts of the thermodynamic space. ©1998 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556015

出版商:AIP    

年代:1998

数据来源: AIP