Interferometric observation of mass transport processes adjacent to tetrahydrofuran clathrate hydrates under nonequilibrium conditions

Kazushige Nagashima, Yoshitaka Yamamoto, Masayoshi Takahashi, Takeshi Komai

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Moire phase shift interferometry was used to monitor the concentration distribution of solute in the solution near the growing and melting tetrahydrofuran (THF) clathrate hydrates. During the growth of hydrate from off-stoichiometric solution, the THF concentration near the growth interface changed due to mass transport of guest molecules. During the growth from THF-17H2O solution, the THF concentration remained unchanged. This, allows the assumption of formation of stoichiometric THF hydrate, which is structure II. The effects of impurities on the growing and melting hydrates were investigated using the stoichiometric solution with the addition of 3wt.% sodium chloride. The salt concentration increased with time by the rejection of salt at the growth interface. The freezing temperature of hydrate was considerably reduced by the local increase in salt concentration. The diffusion length of salt was inversely proportional to the growth velocity and determined the characteristic length of the growth pattern. In contrast to this, during the melting process of hydrate, the dilution of solution was observed near the interface. Consequently, the melting process was inhibited due to a rise in the equilibrium temperature of hydrate.

Original languageEnglish
Pages (from-to)11-24
Number of pages14
JournalFluid Phase Equilibria
Volume214
Issue number1
DOIs
Publication statusPublished - 2003 Nov 1
Externally publishedYes

Keywords

  • Clathrate hydrate
  • Diffusion coefficient
  • Experimental method
  • Interferometry
  • Phase transition
  • Tetrahydrofuran

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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