Determination of critical parameters based on the intensity of transmitted light around gas-liquid interface: Critical parameters of CO2

Masaki Nakayama, Hiroaki Katano, Haruki Sato

Research output: Contribution to journalArticle

Abstract

A precise determination of the critical temperature and density for technically important fluids would be possible on the basis of the digital image for the visual observation of the phase boundary in the vicinity of the critical point since the sensitivity and resolution are higher than those of naked eyes. In addition, the digital image can avoid the personal uncertainty of an observer. A strong density gradient occurs in a sample cell at the critical point due to gravity. It was carefully assessed to determine the critical density, where the density profile in the sample cell can be observed from the luminance profile of a digital image. The density-gradient profile becomes symmetric at the critical point. One of the best fluids, whose thermodynamic properties have been measured with the highest reliability among technically important fluids, would be carbon dioxide. In order to confirm the reliability of the proposed method, the critical temperature and density of carbon dioxide were determined using the digital image. The critical temperature and density values of carbon dioxide are (304.143 ± 0.005) K and (467.7 ± 0.6) kg ·m-3, respectively. The critical temperature and density values agree with the existing best values within estimated uncertainties. The reliability of the method was confirmed. The critical pressure, 7.3795 MPa, corresponding to the determined critical temperature of 304.143 K is also proposed. A new set of parameters for the vapor-pressure equation is also provided.

Original languageEnglish
Pages (from-to)914-929
Number of pages16
JournalInternational Journal of Thermophysics
Volume35
Issue number5
DOIs
Publication statusPublished - 2014

Fingerprint

critical temperature
liquids
gases
carbon dioxide
critical point
fluids
profiles
gradients
visual observation
critical pressure
luminance
cells
vapor pressure
thermodynamic properties
gravitation
sensitivity
high resolution

Keywords

  • Carbon dioxide
  • Critical density
  • Critical temperature
  • Thermodynamic property
  • Transmissive image

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Determination of critical parameters based on the intensity of transmitted light around gas-liquid interface : Critical parameters of CO2. / Nakayama, Masaki; Katano, Hiroaki; Sato, Haruki.

In: International Journal of Thermophysics, Vol. 35, No. 5, 2014, p. 914-929.

Research output: Contribution to journalArticle

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